CONF-880812— Absts. 1988 DE88 013629 Applied Superconductfertty UOfiiOffWiCO Sheraton-Pataca HoW San Francisco, CA August 21-25,190$
Sponsors Lawrence Livermore National Laboratory University of California Department of Energy Office of Fusion Energy and Division of High Energy Physics Bechtel National, Inc. Teledyne Wah Chang -dm Contents
Conference Schedule iv P-3 Plenary HI Map of Conference Center v Materials 48 Session El SQUID Applications 48 P-1 Plenary I ML High Tc Superconductors: High-Speed Josephson Integrated Oxygen Ordering 49 Circuit Technology 1 LI Stability II 50 EA Superconducting Integrated Circuits .... 1 EJ 3 Terminal Devices/IC Processing II .... 51 MA NbTi Processing and Properties 4 MM High Tc Superconductors: LA SSC 5 Miscellaneous Properties 53 EB High Tc Superconductor Electronics I ... 6 LJ Fusion Ill/MHD II 55 MB NbTi: Measurements and AC Losses ... 7 EK High Tc Superconductor Electronics II... 56 LB Fusion I 8 MN High Tc Superconductors: EC Digital Applications 9 Critical Currents II 57 MC NbN, Nb3AI, and Nb3Sn 13 LK Medical Applications 57 LC Stability I 14 EL Particle and IR Detectors 58 MD High Tc Superconductors: MO High Tc Superconductors: Bulk Processing i 16 Characterization 60 ME High Tc Superconductors: LL Energy Storage, Generation, Measurements 17 and Switching 62 LD Fusion II/MHD I 18 MP Nb3Sn: Measurements 63 ED Miscellaneous High Tc MQ High Tc Superconductors: Superconductor Electronics 19 High-Frequency Responses 64 P-2 Plenary II P-4 Plenary IV SMES 26 CEBAF 66 EE Noise in SQUIDs 26 EM Millimeter Wave Technology II 66 MF NbN and Nb3AI 27 MR High Tc Superconductors: LE SMES I 29 Thin Films II 67 EF Millimeter Wave Technoiogy I 30 LM Conductor Testing 68 MG NbTi: AC Losses and Stability 32 EN Josephson Junction Dynamics 69 LF SSC II 34 MS High Tc Superconductors: EG Device Processing 35 Thin Films III 71 MH High Tc Superconductors: LN Magnet Technology 74 Critical Currents I 37 MT High Tc Superconductors: LG SMES II 38 Magnetic Properties and Applications ... 76 EH SQUIDs 38 MU High Tc Superconductors: Ml High Tc Superconductors: Thin Films IV 77 Bulk Properties I 41 LO CEBAF Magnets 78 LH Magnets for Physics 43 MV High Tc Superconductors: MJ Nb3Sn Processing and Properties 45 Bulk Properties II 78 MK High Tc Superconductors: Author index 82 Thin Films I 46
iii Conference Schedule
1 MONDAY AUGUST 17 TUESDAY AuGUST - WEDNESDAY TiuGUSig; • THURSDAY, AUGUST ?S 8:15-9:30 a.m. 8:15-9:30 a.m. 8:15-9:30 a.m. 8:15-9:30 a.m Plenary 1—Gold Ballroom Plenary II—Gold Ballroom Plenary III—Gold Ballroom Plenary IV—Gold Ballroom S. Hasuo W. Hassenzahl J. M. Rowell A. K. Chargin
9:30 a.m.—Coffee 9:30 a.m.—Coffee 9:30 a.m.—Coffee 9:30 a.m.—Coffee
9:45 a.m.-noon Oral 9:45 a.m.-noon Oral 9:45 a.m.-noon Oral 9:45 a.m.-noon Oral EA Superconducting Integrated EE Noise in SQUIDs EN El SQUID Applications C EM Millimeter Wave Circuits EN MF NbN and Nb3AI GB ML High Tc Superconductors: Technology II C MA NbTi Processing and L£ SMES 1 C Oxygen Ordering GB MR High Tc Superconductors: Properties GB LI Stability II EN Thin Films II GB LA SSC C LM Conductor Testing EN
9:45 a.m.-noon Poster 9:45 a.m.-noon Poster 9:45 a.m -noon Poster EF Millimeter Wave EJ 3 Terminal Oevices/IC EN Josephson Junction Technology 1 R Processing II R Dynamics R MG NbTi: AC Losse* and MM High Tc Superconductors: MS High Tc Superconductors: Stability R Miscellaneous Properties R Thin Films III R LF SSC II R LJ Fusion HI/MHO II R LN Magnet Technology R
12:00 noon—Luncheon ns 12:00 noon—Lunch 12:00 noon—Awards Luncheon RS 12:00 noon—Lunch 1:30-3.15 p.m. Oral 1:30-3:15 p.m. Oral 1:30-3:15 p.m. Oral 1:30-3:15 p.m. Oral EB High Tc Superconductor EG Device Processing EN EK High Tc Superconductor MT High Tc Superconductors: Electronics 1 GB MH High Tc Superconductors: Electronics II GB Magnetic Properties and MB NbTi: Measurements and Critical Currents I GB MN High Tc Superconductors: Applications EN AC Losses EN LG SMES II C Critical Currents II EN MU High Tc Superconductor*: LB Fusion 1 C LK Medical Applications C Thin Films IV GB LO CEBAF Magnets C 2 00-4:30 p.m. Poster 2:00-4:30 p.m. Poster 2:00-4:30 D.m. Poster EC Digital Applications R EH SQUIOs R EL Particle and IR Defectors R 2:00-4:30 p.m. Poster MC NbN, Nb3AI, and Nb,Sn R Ml High Tc Superconductors: MO High Tc Superconductors: MV High Tc Superconductors: LC Stability 1 R Bulk Properties 1 R Characterization R Bulk Properties II R LH Magnet* tor Physic* R LL Energy Storage, Generation, and Switching R 3:00-5:30 p.m. Oral 3:30-5:30 p.m. Oral 3:30-5:30 p.m. Dral MD High Tc Superconductors. W Nb3Sn Processing and MP NbjSn: Measurements EN Bulk Processing 1 GB Properties EN MQ High Tc Superconductors: ME High Tc Superconductors: MK High Tc Superconductors: High-Frequency Meeting Room Designation: Measurements EN Thin Films 1 GB Responses GB C = Comstock QC - Garden LD Fusion II/MHD 1 C EN - Emperor Court 7:00-10:00 p.m. Poster 6.00 p.m.—Cocktails RS Norton It = Rose ED Miscellaneous High Tc GB - Gold RS - Ralston Superconductor Electronics R 7:00 p.m.—Banquet GC Ballroom
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Lobby Level Second Floor Session P-1 Plenary I High-Speed Josephson Integrated Circuit Technology 8:15-9:30 a.m., Monday, August 22, 1988
p-1 speed-digital circuits. Main topics are a high-uniformity Junction process, three-dimensional Integration technology, a 4- HIGH-SPEED JOSEPHSON IC TECHNOLOGY*, Shinya Hasuo, Mt microprocessor, and a single chip squid magnetometer- Fujitsu Laboratories Ltd. Atsugi, Fujutsi Limited - Performance Lastly, the author wilt make a comment on the expected of integrated circuits with Josephson junctions have been performance of the digital circuits with h1gh-Tc materials. dramatically improved since niobium junctions were available. Niobium Junctions, especially the Nb/Alo^/Nb junction, exhibit excellent characteristics, such as low leakage current, high •The present research effort Is part of the national research stability against thermal cycii/ig and long term storage, high and development program on "Scientific Computing System", controllability of the critical current, and high conducted under a program set by the Agency of Industrial reproducfbifity. These reliable characteristics encourage u* to Science and Technology, Ministry of International Trade and try making large scale Integrated (LSI) circuits. We are Industry. attempting to make ultra-fast Josephson computers. At present, we can operate a few thousands gate level LSIS. Compared with conventional semiconductor LSIS, the performances of the Josephson LSIS are outstanding in operating speed and power consumption. This is owing to the development of a reproducible and controllable Nb/Alo /Nb junction fabrication process. This Shinya Hasuo, Fujitsu Laboratories Ltd., 10-1, Korinosato- paper describes fabrication technology of niobium based Wakamfya, Atsugi, 243-01, Japan. integrated circuits and applications of the process to high
Session EA Superconducting Integrated Circuits 9:45 a.m.-noon, Monday, August 22, 1988
EA-1
AM ALL-NbM TIME DOHXIM MEFLEtlUMHtll CHIP A 1fl-V JOSEPHSON VOLTAGE STANDARD* FUNCTIONAL ABOVE SK, S. ft.Whit e ley, F. Kuo, H. Radparvar, and S, M. Faris, HYPRES, inc. - Josephson C. A. Mainillcii mid Franrrs L. Lloyd circuits fabricated in niobiua nitride technology can Naliimal Durmu of Siandnnls operate at temperatures approximately twice as high ElrftroinaRiirtir Technology Division as Josephson circuits fabricated fro* elemental JJnuldrr, CO R030S superconductors. This allows a Major simplification in cooling, based on relatively inexpensive two-stage closed-cycle refrigerators. A time domain reflecto- Introduction mcter circuit, previously demonstrated in niobium htiriiisM- vollngr ^landnrds arr liasrd on the far! iliat H .Invrjilisnn junriion in a mi- technology, has been adapted to the niobium nitride rrriuitvr fiild K«*nrra1rs ronitaiH vnltnRc strjis in its IV rurvr nt (lir vol(»grs nhf ;2r wlierr process. The circuit contains a step generator with ii if an iuteRir, f is tlir iiiirrowavi* frrtjnrtiry ami 2r !h lias a drliix-d valur. Early sltndanls a displayed rise time of 5 ps. To produce this tiscci | or 2 jtMirliuiiK (o grnrralrd r^frrenrr vollagrs of a frw millivolts, hillirlasi sfvrral circuit, the design must accommodate the higher pene- tration depth of NbM and the process must provide yrars 'arRc arrays «f 2(H)0 or morr Josrplisun junritniis liavr brrn usnl in many Inburalo- high quality Josephson devices and good uniformity. rirs to n;-iictntr rrfprfiico VHIURPS on lll^ order of \ V jl-4|. Tlirsr tlrvirrs ran lie ns«l Circuit operation at various temperatures has been l.ii voltage stamiards. A series array of 1-101M) 20 levels change with temperature. Thick. MbH films are (H)() jnnriinns woulil extend ilir jnlirrriit simplicity and nrrurncy of a direr! raliliratinn !•> used in the process to suppress flux trapping and tlie Kl-V level rommntily used \u Zetier-diode referenc:1 staiuUrd-i. falibral^irf! and digital edge tapering is used in lieu ol planarization to Yiiltineieis Tlir firsi oWrvalifin "t Josepli-.-n steps at the IU-V level nsed an array of provide good edge coverage. This is the first demon- I 1 \SA iiiiiiitons f.V. The pimi slabititv and larRe microwave power requirement uf lliis stration of a useful circuit component fabricated in nirai inadr its HM- US A prarlital Ntmnlnid iiiBrRiiinl- This paper drsrriors an array with a all-MbH technology. modified design wlnrh resolves llir pinl.lms of stabilily and potvrr mpnrnnent. "
Army Di^igu Fiinin- 1 is n dtawiiiK <>1 llir IU-Y Array. II is H sirnightfriruard rxirnsimt nf h jirevi- mi* 2«7« junction armv driiRii I]. A (inline at niir end of the (\u\' .ollerls 70 IUU (JHz rmlinlioii from a wavrRiiid.- mid dirrrts it into n inirroslripline. I hr nticrosttipfitte ajtlits into Hi pnralM pnths, each >>f wlijrli pns>rs through 11£7 jiinrlinns. The W> inicrostriplines »ir trriiniiatrd in maifli^d loarU. HiRli iuiprdanrr ronm-rtions Kettvern seriinns ailow lhe ilc vullitfte artoss all IS 992 junctions to add in serifs. Blofkinp capacitors in ilie (lie dc * fr< i briitR shorl -.1 thr netwiiik- "Curly*' hriid<> arr usrd in the iiiicroslripliiies to niiitiinijr the rl>ip Area without A .KJSEPIISON YOI.T-UiESTANHAHF) AT 10 VOLTS I'SIN<; lOinpiMiiusiiie the liend radius U» widih rnlio of 3.2. SiRiiifirrtiitly smalirr ratios lead lo A SF.KMFS ARRAY OF |H W2 JUNCTIONS. C A Hamilton, and Prances linaccepl nl>Ie rrflrfliuus at the )>ends 1. Moid. Nniimial lluirati .4 Standards lloiiUW CO S010.1 Joseuhsoi, Hie utmilirr of jitlichons in tarit niicrosiiiplinr section is liiniieil in auout 1200 Ity array standard-, at tin- I V Jevel have l.rn, available U several yean- and attenntilion wlur|, js t-sitniateil to l>r 0.001 dlJ,juiirtioii. After pa^sinf> throiiEh alxmt have hrm adopted Hi a iiimilirr of national Mtnidanfe laboratories where 120(1 juiirti..n« i!,r nijrrowavr pmvrr i<- «iemfirniit!y l^lou thr optimum vxlue for
(1) H. Cokan et al, J. Electrochem. Soc, vol.135, 1019 11988). (2) I. Ishida et al, Ext. Abs. of the 19th Conf. of Solid State Devices and Materials, Tokyo, «U3 (1987). (3) Y. Uada et al, IEEE J. Solid-State Circuit, SC-22, 892 (19B7). (4) M. Kidaka et al, IEEE Electron Device Lett., EDL-fi, 267 (1985).
Y//<*HQ////////.; VOLTAOE Figure 2 A double exposure showing a 10-V array 1-V curve without microwave and a single constant voltage step at 11 V with 4 inW at h~ (IHz n])pliH at the input EA-3 Hb MULTILEVEI ?LANftfli2ATI0N TFCHUOLOGY FOR A SUBSAH0SEC0W) JGSEPHSOH IK-BIT RAM, «S. Nagasawa, Y. Ma-Ja, H. Tsuge, H. Hidaka, I. Ishida, and S. Tahara, KEC Corporation -- Kb aultilevel planarizatlan technology for a Josephsor iK-blt RandMB Access Howry (BAH), with ainlwuB 57Ops access time, has been newly developed. The authors have developed a aultiievel planarization structure, uhicfi consists of, on the Nb ground Fig. 2 Polystyrene etch hack Fig 3 Photomicrncrapb of a fabnca:?d plane, tiro 300n«-thick planarized Nb wiring layers, a aoona- thlck Nb Miring layer, a 500no-tfiick planarized Kb/AlOx/Nb pjanarization fiow char.. Jcse^hscn 1-kbi: RAN3 chip Fig. 4 Cross sections 1 )?* s Ic rpd as a s • ni] I(? flui'^oud^tu^ in t h t ono~juf^ct^un -J(J - » \J * <5'id is d(*!>truf~t*vi?^y refld~Out using the s i rnj if jii^-Cl^on, r*^p s i f^ Q ' C Ju^ct^on SEM photograph through the capac 1 t tjrs. Thp i lQurt J shows wavpio^^S 11 t ^e af c ts s 11 ^e fflcasurprricnt» • he minif^iu,^ access limp of S90ps was obtained for the (D00O0O))( f01 DOT 1 )y address. This co^rpsoonds to a criticfl' pftt^ *or *he X~Qpcod£r, ^'ip to^^l SUWHARy OF "4K JOSEPHSON MEMORY". H.Sujuti. (.fuj.nili. HJamura, T.Imamura. and S. Maiuo. Fujitsu L'n»*ed lOr- SIOJ THICKNESS] Fig. 5 Measured breakdown 200 nm ' voltage between drive wires r n in the I-kbit cell array. ' • ..I n 20 40 60 30 100 120 !40 BREAKDOWN VOLTAGE IV) EA-4 t,g. 3 4K JOSF.PHSOH HEMORV*. H.Suii;*:. fJ.Fijjimal.1, H.Tamura. 1 ~b11 memory arcom p" I s re-. 3 by c L^nbining a 9n-ps 6-64 decode r and 6 read/write tjate dps i i proCucp a hiq»*. voltage o The sense J't CCl r>* 3-stage 4Ji_ 0^ gates wi'JI four inputs. The ry ce! ? IS d i vely coupled to a y connected. circuits, and 8K 7 . 7.7 ma?. The :hp HPT ory «js fab'iciited with Fib,'•AlC/Nb junctions, '00" n •: o:) fOTGC Mi» was reasured to i>i ps. Th i i aid 1 C O Ti "1 jcte( c a prog'•IT set t?/ the Ageicy of Industr•a I 5 c • «i "4K JOSEPHSOK MtHORT Fig. 6 ( figure 1 r; a phe'ograph of the J - ' 1 ~b 11 Joscphson memory chip fafc'-'catp'] yiifi'j 'ifc ft'O, 'Jb jur.ctior.5. The remory consists of 6-64 Ce^cder^ fcr x ari*j ^ dddres5es» rpad'fcritc S6lpct.ion cates, /- and f'— EA-5 JQgyfBQH ittPBKSS OOMHO. UNIT IC TOR A 1-bit MICHOCOiVTRR PHOTOTYPE, S.Ko&ik;*, M.Nak^awn, H.hUwaraira. Y.rjk:uia. VJI.irr.'izaki, M.Af.yiiRi, I. Knroaawn, A.ShnJi, and S.T.ikadj, El'-Ltrotfchnicnl I.'tbcratoi~.' — A lufvphson adclr*s.s U. 4. "re 6-6* -iecoder is constructed with 3-stage of the AND gates. i.-or.*_p;il jtutiCTRTi chip h.i^ ly-n d-sign-rt ;md ra'.iricat>-ci by ' -3.urP •* ^r°"5 ^e Cecoamg t^~e of the ^-64 decoder as a function of uylli^ /.S rai'.:JTjn N*1?N juncticn t*'tjiiifjl'3gy. IMs chip is trp norr-fl ; i-ed bias turrer.*., A m'ninun decoding 11 me of 90 ps ms% ccr".paS''d of .in instmctifjn r^'Rist'T'. IH: lObitt, ;ITJ ir.o:njctir.n obta inc-c. d'-cod-r, a ;;t..ick r>'Rigt'-r( -'hit .two-l-v^ls). ;i nultipl.-x-r, ;«; infi>fi>-'nttT, .lr.tl a progr-an count»-r(PC:'/bit.1. Instructions ri^nTi .i proRr.'CT; K'W t.hip aiv- f-trh«*rt ir.to IH, d"rort»d, and ;i firrjp'-r r-.-xt a:1dr-si3 ar- s-t up to fC. 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Li I 1 y p**rl -.: rui-'ii. T.'i l s >/'.'. l ;i wi * ] ; •* inf > 1 •in'M'! f ••(! i 'i d!i : : i t-xp'-rifr.'-rit a". -.-Mt 't^:-;>h::;i-. r.i. ivcinput ••'•' [ii'*^t •»t.>'-•-• - y:U- T ! ..i Pig. I. Hlock dla~r;im ..1 .• Pip . •? - I'tiotumi crnRraph .iDtwphstin iidiiivga cuiilrtil -.mltl oi a liisiMptiHi.n a Session MA NbTi Processing and Properties 9:45 a.m.-noon, Monday, August 22, 1988 cal current density approaching 3000 A/m-£ at 5T. This paper will MA-1 report on the electrical properties (Jc and n value} and mechanical properties (tensile, springback and bend characteristics) of the DEVELOPMENT Of HIGH CURRENT DENSITY IK KB-TI-TA strand. Piece length distribution obtained for various production ALLOYS, D. C. Urbaleitttr, A. D. Mcliiturff , P. J. I*e. J. billets will be presented. The performance of cables fabricated .HcKlnnell, R. Re»sbotto», U. Starch, P. H. O'larey* and U. K. from the strand will also be reported. Specifically, the critical McDonald*. Applied SuperconductivLty Center. University of current degradation due to cabling and residual twH: in the cable Wisconsin - Recently we have fabricated laboratory acale will be addressed. •ultLfLlaaent co«poaltee of Nb clod high ho«nKeneity Nb-Tl-Tn (Nb44wt.tT115wt.ZTA) In copper. Co-pared to an earlier study using relatively lnhonogeneaua alloy (± 4-Sit.ITa/Tl), this aacerlal had local co-posltlon variations ai < t 2 MA-4 wt.XTaf'Tl. The Kb content variation was saall. The Jc (10"' te) values obtained with the high homogeneity altoy exceeded HECENT ADVANCES IN THE FABRICATION Of MULT I FILAMENTARY NBTI 3000 AJum2 (3 T, 4.2 K), compared to 2200 K/mw2 for the COMPO6TTES DESIGNED FOR USE IM THE SUPEFCONOUCTNGSUPERCOLLIDER E. Grtgory, T.S. Kreitac*, J. Wong. Supercon Inc., B30 Boston Turnpike, Srirawtbury, MA 01545 - O#v«toptn*nl*l and production composites designed progreBt. The Nb-Tl-Ta alloy Is found to precipitate sore by Suptfoon Inc. tor o*# in Superconducting SupcrCoHider (SSC) dipoles are than 2^> volX ^rTl on heat treat went« Thl B OCCUTA a little discusMd. Additions of tantalum lo trie niobium-titanium *Woy and manganese • ore rapidly than tor NM6.5wt.ZTl. The full r.>sulta of our to m« copptr mairis havt b#*n investigated using stale of the ait composite optl-icatlan proceas will be reported at the conference. designs and techniques of bMei labricaiion. Materials oi a developmental nature include two 305 mm drameier billets designed lo yield 2 5 urn * Penal Ub diameter filaments at wire sizes of 0.01 mm and 0.65 mm. respectively. *Teledyne W«h Chang Albany Supercon Inc "s ftrti production biHets tor the SSC {(hose procured on a cost SC plus fixed fee basis) have produced saver a I lengths in excess oi 32 fcm Histograms for these bidets will be included. MA-2 MICROSTRUCTURE CONTROL IN HIGH Tl NlTi ALLOYS / P. J, MA-5 Lcc, J. NcRlnnclL and D. C. Larba]e«tler, Applied ENHANCED CURRENT CARRYING CAPACITY OF MULT I FILAMENTARY Superconductivity Center, Unlveraity of Wisconsin - High Tl SUPERCONDUCTORS THROUGH THE USE OF COLD WORKED NBTI ALLOY. * NbTl alloys havr lupcrlar current carrying capabtlltles at low T.S. Krailtcfc. F.S. von Goeler. E Gregory. J, Wong. Supercon Inc. 830 fields {< 4 T) co-pared to conventional 46.5wt.XTl alloys but Boston Turnpike, Shrewsbury, MA 01545 The current carrying capacity their alcroatructure la sore difficult to cptlnlze for ol muHtfilameniary NbTi superconductors is shown to be hignly dependent drawabtlity and flux-plnnlng. By using Cran»«lsslon electron upon the Ihermo-mechanical processing hrsiory ot the NbTi alloys prior lo •Icroicopy a relationship haa been deternlned between strain, and during eilruston. In the past, investigators have lowered the temper' co-poaltlon^and precipitation aodes tw, grain boundary o-Tl alure ot extrusion in order to improve J , but bonding problems were or UldMniticten orTl). Furthermore detailed quantification c experienced. Since that lime. Supercon Inc. has introduced hoi isosiatic of th* alcrostructures reveals a itrong dependence of pressing lo improva the bonding and more work has been dons on hydrostatic precipitation rate on co-poiitlon. These observations add extrusion. As an alternative to an extrusion press dedicated solely to Insights Into the significance of alLoy homogeneity and have hydrostatic use, Supercon Inc., in cooperation with the BaiteMe Memorial alao reaulted In dramatically 1-proved critical current institute, has demonstrated the feasibility ot converting a midsize 41250 densities (reported elsewhere at this conference). ton) conventional extrusion press to dual hydrostatic/conventional use This paper wiH include a discussion of Supercon inc.'s recent efforts to maintain 'Research supported by the Electric Power Research more ol the effects ot coW work and heal treatment carried out on the NbTi Institute, Superconductivity Magnetic Energy Storage: Basic alloy prior to exiruson. white stiH achieving good bonding and piece length RiD, RP:8981 ' Supported in pan by U.S. Dept. of Energy Small Business Innovative MA-3 Research Contract tDEACO1B5ER8032l FINE FILAMENT NbTi CONDUCTORS FOR THE SSC-*H.C. Kanithi, i_.G. King, B.A. Zeitlin, and R.H. Scanlan - In support of the SSr MA-6 mgnet development program, 1GC-Advanced Superconductors Inc. has produced over 4500 lbs of fine fflanent wire. Since the SSC would THE EFFECT OF TITANIC CONTEST OS THE CLOSA1. f INS I St. require a large volume production at the most economical price, FORCK IN NWh.WT.5Tl TO X\t>2%n . 1T1 , .!. C. MrKlnnril, t\ !. large billets measuring 1?" dia have been used for this prototype L*e and D. C. Larbalest ier, Applied Siiperriim1ti<-( 1 vity C*nttT, wire production. Soth inner and outer grades of wire have been processed with NbTi filament diameter of 5 to 9 micrometers, de- that hi Kh Ti NbTl alloys (r.R. NbhSwt .171) h.tv.? A pl-inti,; pending on the magnet design requirements. The Increase in billet diameter from 10" in the past to 12" resulted in an improved criti- Nb4 6.livt.tTl.. We have been lUudylnt: tilRh TI alloys t. effeciivefy form a solid mass The hexed lilament shape persists for the mosl part Irom extrusio.'i down lo final wire si2« maintaining order and uniformity among ihe filaments, eliminating areas with missing filamenis and greatly MA-7 reducing the chance of 'filament sausaging'; qualities which ca^noi be attained bf stacking round mcnofilamenis with their characteristic inclusion of void H1OH C.'RREST CEfi'ilTY OF NOTi OOIPOSITE, S. tkin-j, space By avoiding these void spaces, copper to superconductor ratio calculations are made more accurate and Ihe 'concave* effect of the billet is reduced, a resutt ol isosialic pressing wilh excest amounts of void space. Finally, longitudinal and cross-sectk>nal uniformity not only increases Jc, criticil i-jitint •1i*n«;ity »r» r^tv»rt*>-1 in ; ?ii M nafor. .Ic ^ 1000 but reduces areas ol weakness that would occur In an otherwise nonunilorm and sausag^d wire, which consequently improves piece length yield. * Supported in part by U S. Department ol Energy, Small Business Innovation Research Contract DE-AC01-87ER80437 MA-8 PROGHESS IN GEOMETRIC UNIFORMITY ITS ASSESMENT AND PROMOTION OF SUPERCONDUCTING PERFORMANCE IN SSC STRANDS.* P. Session LA SSC 9:45 a.m.-noon, Monday, August 22, 1988 Manufacturing technique*. Son* atgnet* hiv* be#n instruaented LA-1 •ith atny voltage taps allowing detailed study of quench location »nd propogetion. Strain g*g«« and aotion senior• have STAR'S OF Tilt SSC SLTERCONDL'CnNC MAGNET PROGRAM, been used to study the response of the aagnet structure to ) Peoples for the teams .it B\'L. Fermilab, LB1., SSC-CDG - Each theraal and electroaagnetic forces. collider ring of the Superconducting Super Collider (SSC) will contain nearly 4,000 superoonductirtR magnets. The parameters ol these magnets will be presented During the past year, six full- •fork Supported by the U.S. Daoartaent of Energy. length prototype dipoles and a larger number of shorter dipoles of the same cross section were built by a collaboration of Brookhaven National Laboratory, Fermi National Accelerator LA-4 Laboratory, and Lawrence Berkeley I-aboratory under the direction of the Central '"design Croup of the SSC The results of MEASUREMENT OF AXIAL END LOADS IN LBLSTYLE SSC MODEL the test* of these magnets will be reported, a* will the DIPOLE MAGNETS.- Jon Zbacmk. Cra* Peters, and Oyde T-ylu.. Lawrence Berkeley lAtwrwory • The LRL-ttyle dipofc ma(Aei for the SSC features almmm coUan w»h tapered measurement oi the properties of the superconducting cables keys thai are axd lo provide an aumiMhal presueai to the conductor bundle such thai ihe that were used in the fabrication of these magnets bjrHJferunaMU under compression ai ihe design Held. The coils are axaUy reatnufied by rather sdfr end plain which are preloaded lo apnro*imaie]y 10 kip. The end plates hive recently been inttrumcnttd with unin pvp* Md calitmed , which allows i» u> determine the load applied 10 ihe end plate and [he aiitl dericcuon of the coil by monitormg the urain lauic LA-2 output. TV iiudy WM maiivaKd by imr desire uyndenUK) Uc uial mechamci of the LBL TE! ilipole models, in parucular as it may relate lo tramifif. We report design fcaiwxs of the instrumented cndptatei. cairbrauon procedwej. and test results on several model*, inclwfcng a y. G 1.8 m tone msptet wtdi a welded nawttew ttect riwll and two l-m kma; modcU with a damped suinlo- ml ihcll The Here— m mcaaurcd cud toad m all Ihree CMM a ytn/bciK m current and ikowt little hy«eresii. The rewlis arc damsMd in terms of a model which ttkes mlo account Ihe fneasurcd Uiffnawa and fricum terms at parameien. ry A set Ion g dipoles bull t and •This wnrk wat supportul by the Dtttcwx. Office of Energy Research. Office of High Energy C Ct I 1 1 E wound with par den »nd Nucleaf Physics, High Energy Physics Division. U.S. Dtpi. of Energy, under Contract 5 itV high hoaog. ty NbTl a wo Uy«r graded So t)E -ACO3-76S TO0098 11 is The LA-5 MAGNETIC REIJ) DECAV IN MODEL SSC DIK>L£S.» W. S. Gilbert, R F. Althws. P. J. Bank. R. W Benjegerdes. M. A Green. M. I. Green, and R. M. ScanUn. Leng th 17 B Bannert Tralnl ng and fL« Id quality data, frr.r. UWTCMX Berkeley Laboratory • We have observed that son* of our model SSC dnoles have long time conitani decays of the magnelK field harmonics with amplitudes large enough to reiuli in significant beam loss, if they arc not corrected. The magnets were run at consum current u the SSC injection field level of 0.3 tcsla (or o*e hour and ckaitgcs tn the magnetic field were observed. One explanation for the observed field decay is time dependeni superconductor magnetization. Data is [TJcnted on how- Ihe decay changes with previous flux hiuory Similar magnets with differtni Nb-Ti filament spacing! and main- materials have different loaf time constant field decay A kHeoreucal model using proximity coupling for ihe LA-3 otiscrved (kid decay is presented TESTS Of FULL SCALE SSC RAO DIPOLE UAGNETS,* J. Strait, B- C Brown, R. Hanft, M Kuchnir, U. LWM, 'This work wMSta^poned by the Dtrecior. Office of Energy- Research. Office o( High Energy R Lundy, P. U«nt«ch, P. 0. Uciuf, A. Hclnturf< mnd J. R. Orr, and Nuclear. Ptyuci, High Energy Phyiiu Divtuon. U.S. Dcpi. of Energy, under Connect F«r«> National Accelerator Laboratory, J. Cottinyhaa, P. Oahl, No DE-ACQ3-7&SF00098. G. Carwtis, U. Carter, A. GKosh, C. Coodiait, A. Qr—nm, J rt«rr«ra, S. Kahn, E. Kvily, C Morgan, A. Profit, W Saapson, i. 5crirwid*r, R, Shutt, P. Thoapton, P flandcrvr, LA-6 and E. fllltn, Brookhavan Hational Laboratory, S. Caspi, REDUCTION IN DIPOLE HELD DISTORTIONS WITH FINE RMMENTS LN 1. Gilbert, R. Uausar, C. PeUn, J. R«ch«o, R. ftoyr, A SPECIAL MATRIX* R M. Scanlan and C E. Tiyk*. Ijwrence Berketey Laboratory: R. Scan I an, and C. Taylor, Lawrence Berkeley Laboratory, E Gregory and T 5 Kreilick, Superccm. Inc A recurring proNem in the design and A. Devred, J. Kauoairts, J. Peoples, J. Toapkint and operation of superconducting accelerate* d^mle magneu.«the distortion of the dtpotc field R. ScheraMr, SSC Central Design Group. at the injection poim. which is lyptcally about 5* ot the ituuimum operaiing 5cW At injection, a significant field distortion is prewni. due In local persistent currents in the Data are presented on the quench performance tr>d »ech»nical upcKonductor TVtse peniiieiit curreno i« propnruonal to he riamcnt diameter; hence, beh««ior of full scale devetopewnt dipole aagoets for the SSC. an obvious approach reducing the effect is to reduce the filament diameter However, manufacturing conttmnu limit the etieiH thai this can be done filaments muu he spaced To stud/ the causes of training in these aegoets, * series of CICK!) together io prevent instabilities from developing duri.tg drawing, bul at small dipoles has been tested in ehich several design feetores have spacing, eg . tcs.^ than I um, the filaments become coupled by persistent current* which been varied. bUgnets have been built -ith different types of fin* tn the high purity copper malnx Tradittonally. a CuNi alloy matnt has been restraint against axial aotion, vith different end designs, employed lo reduce ihis type of coupling However. Cotimgs has pronowd annthei with different collar Materials and with different approach lot decoupling filament] which offer- wvenl adtanugcj This approach utilizes (he greatly enhanced scaoering potential of a magnetic impurity anti so that a dilute alloy results on a second scnf\of billets *itha filamwil dumewr of 2 ^ can be employed in place of the tO-50 writ- Ni alloys. Production sire hliccs concuning a Cu-0 5 *l* Mn alloy matni surrounding 5 um diameter NbTi filamenu hive h«n •Tim work was supported hy ihe Direcior, Office of Hn rgy RcscarrS. Olftic of JIIKII fatacurd 10 SSC conductor specifier ions. This maicnal has been cabled and wound into a Energy and Nuclear Physics, H.«h Eneigy Iliysics DIVISMI i. L: S Dcpi. n! lineigy. undci Im dipole. Results of ihii mignei test, including ihc effeci of ihc CuMn main* on Contract No. DE AC01-76SFIXKWK mjccUKi field distortion and on nugn:i training behavioc. »ili tic reported. In addition. Session EB High Tc Superconductor Electronics I 1:30-3:15 p.m., Monday, August 22, 1988 EB-1 Fig. 1. I-V characteristic of Y-Ba- FABRICATION OF S N-S JOSEPHSON JUNCTIONS OF Cu-O/Au/Nb junction with the Y-Ba-Cu-O/Au/Nb TiilN FILM SANDWICHES. H. Akoh. F. application of a 9.216-GHz Shlnoki. M. Takahashl. and S. Takada. Electroterhnlcal microwave radiation at 4.2 K. The Laboratory — We have fabricated S-N-S Josephson junctions configuration of the junction is which consist of the films of V-Ba-Cu-O/Au/Nb sandwiches, by schematically shown in the inset. making use of the proximity effect. The Shapiro steps with the harmonic and subhannonic according to the ac- Josephson effect are observed under the microwave radiation In the Junction?. The temperature dependence and magnetic field dependence o* the critical current confirm that tic Junctions behave as Josephson Junctions. There are two key points to fabricate this type of the Junction: (i) The Au film which is hard to be oxidized is chosen as a normal metal. Ilil The plasma oxidation process with high-O2 pressure and low- rf power is introduced to improve the surface of the oxide superconducting films before deposition of the Au layer. Fig. 2. Magnetic field de- Ic(mA 1- o-Cu-O/flu/Nb pendence of crilical currem Fabrication of S-N-S Joscphson Junctions of f T'l ?K for Y-Ba-Cu-O / Au / Nb Y-Ba-Cu-O/Au/Nb Thin Film Sandwiches h \ junction at 4.2 K. ' 20 H. Akoh. F. Shinoki. M. Takahashi. and S. Takada Blectrotecnnical Laboratory \ / 1-1-4 Umezono, Tsukuba, Ibaraki 305, Japan 10 Summary V , 0 Thin films of the high-TV oxide superconductors have attracted a great deal of • 4 -2 0 2 t interest and been intensively investigated for its various applications as well as an Hiic'n understanding of its fundamental principles. Application for superconducting electronics requires not only the good qualities of the films but also the control of EB-2 the interfacial properties between the films of oxide superconductors and olher Y-Ba-Cu-0/Nb JOSEPHSON TUNNEL JUNCTIONSj A. NKkiyiM, mails. In this paper, we report the fabrication of Ihe superconducior-normal- A. Inoue*, K, Takauchl*, H. I to and if. Ciube , University ol superconductor (S-N-S) Josephson junctions which consist of Y-Ba-Cu-O/Au/Nb Kanagava, University of Tokyo* - Y-3a-Cu-0/A10 /Kb Josephaon tunnel junctions were fabricated using electron-be** thin films. The junctions reveal the ac-Josephson effect under microwave evaporation of Al and Nb fills. Sintered Y-Ba-Cu-0 was used as radiation. Moreover, we studied the temperature dependence and the magnetic base elecrode. First, the upper and lower surfaces of the sintered Y-Ba-Cu-0 were polished with A^CN powder and Au thin dependence of the critical current in the junctions. fill was deposited for an ohaic contact on the lover surface• Next, tunnel barriers of junctions were forced using natural A configuration of the junction used in the present experiment is schematically oxidation of Al thin layer deposited on the upper surface. shown in the inset of Fig. 1. Y-Ba-Cu-0 thin films were deposited on SrT:O3 Finally, Nb counter-elecrode was deposited through a aetal aask. Reaction of Y-Ba-Cu-0 and Al was kept down by Au substrates by using an rf-sputtering method. In order to make the superconduct- interlayer or water-cooling of substrate at the junction ing films, post-deposition annealing was carried out in flowing OT at 710 °C for fabrication. Superconducting Josephson current, hysteresis of I-V curve, which were typical features of tunnel-type Josepnaon 10 h. In spite of the annealing process, the films showed the smooth surface with Junctions, were observed at 4.2 K. Moreover, Joaephscn current small grains of less than 100 nm. The value of a transition temperature for the was aodurated by wgnetic field. Sf-induced voltage steps at a film was 67 K. Before evaporating an Au thin film as a normal layer, ihe plasma voltage greater than 0.4. aV were also clearly observed. oxidation was carried out with an O2 pressure of 133 Pa and an rf power of 10 W for 1 h, in order to improve the surface layer of the Y-Ba-Cu-0 films. Finally, EB-3 the junction was accomplished by sputtering deposition of an Nb film using a OPTIMIZATION OP YBCO SURFACES FOR TUNNEL JUNCTIONS," J. R. Ga.va.lcr, A. I. Bracinski, U. C. Forrester, and metal mask. J. Talvacchio, Vcitinghouie RAD Center - We have established In order to verify the junction as a Josephson junction, a microwave was that in YBCO tilma, prepared by annealing amorphous oxide deposits, atoaic mtfrmfmtian is a •ajar cause ot surface applied to the junction. Figure 1 shows the I-V characteristic of the junction with degradation independent of any reactions with the aabient Au thickness of 30 nm under the microwave radiation with the frequency / of atmosphere. We are now preparing filas under conditions which •iniaise atoaic segregation. These filas are deposited on (100) 9.216 GHz at 4.2 K. As is seen in the figure, the first harmonic step is observed SrTiO. substrataa and have the a-utis noraal to the fila plane. at the voltage of hf 12 e due to the ac-Josephson effect. In addition, a Both in-situ XPS and ex-situ Auger depth profiling indicate that they &re highly homogeneous and have proptr stoichioaetry up to subharmonic step at the voltage of (1/2) hf/ 2e is observed. their surfaces. At 4.2K, contact resistivities below 4 * 10"lo oha-caa have been attained with gold overlayers. Junctions have Figure 2 shows the magnetic field dependence of the critical current lc at 4.2 been foraed by depositing thin Au proximity layers over the YBCO K, which exhibits the Fraunhofer pattern. This magnetic field dependence of lc filas followed by MgO barriers and Nb counterelectrodes. Weak- link shorts w«re observed in soae of these junctions indicating shows the behavior of the self-field limited junction, which means that the that the UgO barriers were "patchy*. Other junctions were found junction size is larger than the Josephson penetration depth. Note thai the to be ohaic. We are now investigating the characteristics of junctions aade with a variety of barrier layers to deteraine Fraunhofcr pattern occurs definitely in the junction of Y-Ba-Cu-O/Au/Nb whether functional tunnel junctions can be fabricated with YBCO sandwich structure, nol in the grain boundaries of the Y-Ba-Cu-0 film, since the electrodes. critical current of the Y-Ba-Cu-O film had no changes when the magneiic field was increased up to 65 x 10-* T. •Supported in psxt by AFOSfi Contract No. F48G2O-B8~C~O039. EB-4 TtlKHEL JUHCTICKS BEIVEQf Y, Bn JCQJO^ SEdZ CKVSTALS AMD Pb ran* FILMS. G.B&lecrtrlno, A.M.Cuoolo, R.D1 IBO. S.Faoa, A.Saggetia*. B.S&vo. R.Vafillo. dyartlaoito dl Fisloa Dnlverslta' dl SflJamo - High Tc tunnel Junctions have been mostly fabricated ty sintered Y1BaICuJ07.Itwse electrodes and fcyeithe r paint ocat«ts or thin fila euperoanducting oounterelectrodae. In both oosee the current voltage characteristic* cannot be EB-6 easily explained in terse of the BCS superocoluctlng density of MILLIMETER-WAVE SURFACE IMPEDANCE MEASUREMENTS states: scBBtlme unreproducUile sharp peoka of the dyaa*loal OF HIGH TEMPERATURE SUPERCONDUCTORS, * T.L. Hylton, K. Ciiar, M.R. Beasley, A. Kapitulnik, Stanford University resistance or a large zero hiss ancaaly oan be measured. de» Department of Applied Physics and J.P. Carini, G. Gruner. phenomena oan be ascribed both to the granular stnwtuie of the University of California, Los Angeles, Department of Physics and Solid State Science Center - We have measured the sintered electrode and to the interface layer which font the nillimeter-'.vave surface impedance of highly oriented thin tunnel barrier. To avoid, these proiueoe we fabricated tunnel film samples of high-Tc superconductors, including YBCO and BCSCO. Thin films of these superconductors with low Juncv-jns having a Y,Ba2Qi307., single crystal base electrode, a surface resistances will be crucial in potential high thin Pt? fila oounterelectrode and a tunnel harrier either frequency applications such as millimeter-wave transmission lines and IC interconnects In contrast to BCS naturally grown on the crystal or aade up of aagneelun or type predictions, our samples shew larps residual losses tantalum ccdrJe artificially deposited. As a function of the even at low temperature. The losses at low temperature at 100 and 150 GHz are comparable to copper different fabrication prooeduree we have performed a preli«inary p pp analysis of both the structure of the tunnel barrier and the low upported by the NSF.T. Hylton supported by AT&T holarship, A. Kapitulnik is a Sloan Fel'ow frequencies noise spectral density. •Laboratcri Hazlanali dl FTascati I.N.F.K. EB-7 PICOSECOND PULSE PROPAGATION ON SUPERCONDUCTING TRANSMISSION LINES,* D.R. EB-5 Dykaar, J.M. Chwalck. R. Sobolcwski,** J.F. Whitakcr, T.Y. Hsiang, and G.A. Mourou, The University of Rochester, D.K. Ferrari, Lathrop, S.E. Russek, and R.A. Buhrman, Cornell University -- We have shown previously thai picosecond rise time signals could '!" • ' • nr ..vs.- 1 be propagated on and accurately modeled for ordinary and high Tc -..:. s. •••z.*.-. T .1 , >v. Arpn (YBCO) thin film^ superconducting transmission lines. In this study we present measured and simulated results for propagation -.:< -:-..:,»- y r.-.f.::- '. :. r-..„. ,r,.. .,-: ••-. t-i lengths of up to 10m in ordinary superconducting coaxial cable and high Tc (YBCO) thin film transmission lines, as well as results for r.— ..„;. .... - ... . YBCO lines fabricated on MgO substrates. . -C . . JV -l .. j ;, ' • y • *Work supported by the Air Force Office of Scientific Research " , ' (F49620-87-C-0016). Laboratory for Laser Energetics, NSF lDMR-85-06689). the Office of Naval Research and by the National a, Science Foundation through suppon of the National Nanofabrication '.'in::: Facility at Cornell. ** Permanent address : Institute of Physics, Polish Academy of Sciences, Pl-02668, Warszawa, Poland. :- .-, ,-! very 'J.F. Whitakcr, R. Sobolcwski. D.R. Dykaar, T.Y. Hsiang, and ... -. G.A. Mourou. IEEE MTT. Vol. 36, No. 2, 277 (1988). 2D.R. Dylcaar, J.M. Chwalek, R. Sobolcwski. T.Y. Hsiang, G.A. -•<• Mourou, D.K Lathrop, S.E. Russek, and R.A. Buhrman, To be published. Applied Physics Letters, 2 May 198S. Session MB NbTi: Measurements and AC Losses 1:30-3:15 p.m., Monday, August 22,1988 inductions o!" 0-5 T and 1 T respectively, (the MB-1 unity W/(Am) • (losses tn ¥/n?)/(overall JB In A/m'/ being a nee3ure of the wire performance), THE EFFECT OF SELF FIELD ON THE CRITICAL CURRENT we have shown that auih wires are susceptible to DETERMINATION OF HULTIFILAMENTARY SUPERCONDUCTORS. H proxtnity effects between neighbouring filaments. Carber. A K Ghosh and U B Saapson. BrooV.haven Nation In this article we present AC loss measurements al Laboratory - In the detern Inat ion of the cr It leal cur for a iew series of vires where this proaim.tty rent - O_) of large cross section conductors such an ih* effect has been greatly reduced by increaalng the cables used in accelerator dipoles or the aonollthic con distance between the f.llanents whilst retaining ductors used In HRI magnets the self field produced by high values of the overall critical current the transport current In the conductor Itself has to be density, typically 3000 A/mm2 at 0.? T. For the taken Into account to obtain » "true" value for the crlc noal perforoant wires 50 Hs AC losses in V/(Am) leal current This Is relevant when the perfornance of for snail test coils are a factor of 10 lower for cab It's Is compared to th#t of the strands used to fora O.b T peak field and a factor of 3 lower at 1 T the cable In the single strand case if no correct!on is peak field. Magnetisation losses as a function of made for self field, then larger vices will appear to fi lament diameter obtained for short samples have a proportionately less critical current density than •n>1Ua;e that in wires with negligible proximity ana Her wires Data are presented that clearly show the coupling we baiiefit from a reduction of losses at need for self field correct!on in the proper evaluatIon low field inductions, as compared to that of. for example, the dependance of Jc on strain for NbTl calculated by the Bean model, due to reversible conposItes Further evidence of the need to compensate mot'on of the flux 1Ine3. MB-3 r.enr ft Energy VOLTAGE DROP PROFILE IN SUPERCONDUCTING CABLE STRANDS,* L. F Goodrich and S L Bray. National Bureau of Standards, Boulder, CO BO3O3 - The electrical transport properties of NbTi strands extracted from Rutherford cables were studied to MB-2 deiprmine the relative effects of strand location nnd field fiTi^jf1 Oecr^tix^d superconductine critical "Current measurenients T: r-; LAKE:;? A r - r:tr: «:KE:;, J . ? - rave , A . Fevrnr, •-•••re ir.ide on two different samples which were fabricated under controlled conditions (cables provided by Lawrence Berkeley LrtiDocfltorv) . Those Session LB Fusion I 1:30-3:15 p.m., Monday, August 22, 1988 - the NbTi winding was brought at 1.8 K within another LB-1 day Operation started in April, with a toroidal field of 2 teslas, MAGNET SYSTEMS fOR THE INTERNATIONAL THERMONUCLEAR discharges of 500 kA with a 3 second current flat top were EXPERIMENTAL REACTOR,* C. D. Henning and J. R. Miller, Lawrence obtained after a few days. Machine parameters will be raised to Livermore National Laboratory - The International Thermonuclear their nomincl values (B K 4.5 teslas HW\ Ip B 1.7 MA) during Exper1«ntal Reactor 1s now completing a definition phase as a beginning of a three-year design effort. Preliminary parameters for the superconducting magnet system have been established to guide further and more detailed design work. Radiation tolerance of the superconductors and Insulators has been of prime Importance, since 1t sets requirements for the neutron- sfife?ci dimension and sensitively Influences reactor size. The major levels of mechanical stress 1n the structure appear 1n cases of the Inboard legs of the toroidal-f-ield (TF) colls. The B. Turck, Association EURATOM-CEA sur la Fusion, Dopartemont de winding pack of the TF coils Includes a significant fraction of Recherches sur la Fusion Controlee, Centre d'Etudes Nucleaires steel that provides support against 1n-plane separating loads, de Cadarache 13108 - SAINT-PAUL-LEZ-DURANCE CEDEX FRANCE. but the winding pack offers little support against out-of-plane loads, unless shear-bonding of the conductors can be maintained. The removal of heat from nuclear and ac loads has not been a LB-3 fundamental limit to design, but has non-negligible economic THE DESIGN OF A HIGH FIELD OHMIC HEATING consequences. We present the results of trade studies on these issues, which have led to the selection of the preliminary ITER (OH) COIL FOR A SUPERCONDUCTING TOKAMAK, BASED ON Magnet Systems design parameters. THE US-DPC, " M. O. Hoenig and M. M. Sleeves, MIT Plasma *This work was performed under the auspices of the U.S. Fusion Center - The on-going fabrication of the US-DPC Department of Energy by the Lawrence Livermore National test coil in US industry is generating a series of industrial Laboratory under Contract W-7405-Eng-48. scale processes with capability to manufacture a 14 to 15 T OH coil using advanced 30 to 40 kA Nb3Sn cable-in- LB-2 conduit (CICC) conductors. The paper defines the OH coil as TORE SUPRA: A TOKAMAK WITH SUPERCONDUCTING TOROIDAL a 2 m diameter solenoid consisting of stacks of identical FIELD COILS, STATUS REPORT AFTER THE FIRST PLASMAS, TORE SUPRA double-pancakes. While the proof of this technology has yet Team, presented by B. Turck, Association EURATOH-CEA stir la Fusion, Departement de Recherches sut la Fusion Controlee, to be demonstrated, the OH coil design presented in the Centre d'Etudes Nucleaires de Cadarache 13108 - SAINT-PAUL-LEZ- paper appears to satisfy alt known magnetic, pulsed loss. DURANCE CEDEX FRANCE. TORE SUPRA is a toksmak implemented on structural, hydraulic, tbermodynamic, as wetl as economic the site of CEN/Cadarache by the EURATOM-CEA Association. The machine technology integrates all problems related to the requirements of a compact superconducting ohmic heating fabrication and the operation of large cryogenic superconducting central solenoid . The US-DPC performance tests, coils and of the associated cryogenic system. TORE SUPRA will scheduled for 1989/90 should provide the required proof of provide • significant experience to prepare the next generation of machines for controlled fusion. TORE SUPRA is designed to concept. The tests will take place at the Japanese implement a large physics program that takes advantage of the Demonstration Poloidal Coil Test Facility (DPCF) at Tokai, Japan. The physical size of the US-DPC coii and its CICC conductor, coupled with a realistic manufacturing process are designed to lead directly to a practical and The cooling down ol the TF magnet was achieved in three steps: economical superconducting OH magnet. - cooling of the shields and of the 160 ton coil system at 80 K in 8 days - cooling the coils from 80 K to 4,5 K in 7 days •Supported by DOE Contract DE-AC02-78ET-51013 the latest status of the coll fabrication and the construction LB-4 and testint status of the DPC facility which is composed of * 350- g/s. 4-K helium pump and a 5-kV, 5fi-iiA power supply and BO on. RECEXT PROGRESS IS THE DEMO. POI.OIDAI. COM. PROGRAM II. Tsuji. S. Shiiaiolo, T. Ando. T. Hlyua. V. Takatiashl. ". Nlshi, F. Tada. K. Yoshlda. K. Okuno. h. Koizumi, i]. SakaJJma. T. Kato, K. Hnwano. II. YaaaBura, M. Sato, Japan Atoilc Energy LB-5 Research Institute. T. Sato. T. Ichlhara. Mitsubishi Elec Corp. DESIGN OF THE PROTO-TYPE CONDUCTORS FOR THE KLSJOJt - As a lajor RtD for superconducting coils after the 1EA large EXPERIMENTAL REACTOR. K. Yoshtda, M. F. Mshl, Y. Takahashi. Coll Task, Japan Atomic Energy Research Institute (JAKRI) has II. Tsujl, K. Koizumi. K. Okuno. and T. Ando. Japan Atomic been performing the Demo. Pololldal Coil (DPC) Program- In this Energy Research Institute - After the Large Coii Task, we have prograa. three pulsed coils, DPC-ll. V2 and DPC-EX are being developed iho proto-type conductors of the toroidal col] for built to develop the technology required for the construction th<: fusion experimental reactor. Specifications of the of Inner poloEdal colls of the Fusion Experimental Reactor. crnducior are expected as follows: Major parameters of Ihcsu coils are shown In the following table. (1) conductor type : forced flow. (2) operation current : 30 kA at 12 T and 4.2 K, Superconductor *b-TI Sb^Sn (3) critical current : 60 kA at 12 T and 4.2 K, Operating Current 30 kA 10 kA (4) current density of winding : 30 - 40 A/ma , Design Pulsed Field 7 T/S 10 T/s 15) applied pulsed field : 1 T/B - 10 s, 10 T/s - 100 as, •Indln? Inner Dlaieter 1.0 • 1.0 m (6) inlet helium : 4.2 K. 4 - 10 bar. •Inding Outer Diameter 2.0 m l.G m (7) ainlaua bending radius : 1.5 a. Stored Energy 30 KJ Total 40 "J Three type conductors are candldated for conductor development All of the strands for DPC-l'l, 12 has been fabricated. Its pulsed program as follows: loss time constant measured for confirmation was 0.32 as at 7 T. (a) TMC-FF type : hollow cooled type and Test Nodule CoJl resulting In the loss effective resistivity of I.7E-8 ohm«m. Nb3Sn conductor technology. Cabling procedure for the conductor of DPC-EX pas selected to be (b) Preformed armor type : srai-resct-wlnd technique, 9«17 instead of 3«3*17 to lessen deformation of each strands cable-ln-condult and double conduit. during fabrication. The temperature Increase by eddy current (c) Advanced disk type : scei-react-wlnd technique and disk toss In the support structures which arc faced to forced-cooled reinforced. winding was analyzed for the finally designed shape and fabrication This paper describe.-; detailed design parameters and analysis of Ihe structures has also been started. This paper describes results of three type candidate conductor. Session EC Digital Applications 2:00-4:30 p.m., Monday, August 22,1988 EC-1 EC-4 A JOSEPHSON ANALOG LIMITER CIRC LIT * D. A. Pturttn. D. A VARIABLE HYSTERESIS APERTURING METHOD FOR Hebtn. md T. Von Duzer, Electronics Research Laboratory, V- C. Beritky. 94720 •• We SUPERCONDUCTING COUNTING A/D CONVERSION, G. S. Lee, TRW Space have designed, fabricated and successfully tested > Joscphson integrated ciruii thai is used and Technology Group — We present an aperturing method for 10 limit the range of an analog input signal. This is a very mcfut function when applied lo existing foxphson comparator designs in thai ii extends ihe useful dynamic range of OK superconducting counting A/D converters. We have given the scheme comparator and can thus enable the construction of A/D conveners wkh more resolution the acronym TRAP, which stands for Time Release after Aperturing of than was previously pouiMe. The circuit consists of a single Josephion junction with a Pulses TRAP utilizes a large pi. two-Junction SQUID quantizer and suppressed critical current. The impedance of this suppressed junction consists of the non- plays on the ability to control the amount of hysteresis available in linear quasipanicle resistance in parallel with the capacitance of the junction. When con- nected to ground, this device has the appearance of a bilateral diode which can be used to such a SQUID incoming information from the analog signal can other be shunt signals outside a * Vf range. In our implementation, the junction capacitance is used immediately processed ny the quantizer or "trapped" and output at a to advantage as one pole of a second order low-pass filter, the other element of which is & later time We explain how this control can be used to form picosecond thin-film inductor. This filter can perform the function or a slew-rate limiting filter at the aperture for counting A/D converters, eliminating pulse-skipping input to a high-speed comparator We have fabricated individual junctions and measured their suppression characteristics and have found a 2nm x 4.5um junction with a nominal problems SPICE simulations confirm the ideal behavior of the TRAP. critical current of 180 uA can be suppressed to less than 4 \xA of critical current with a 12.5 mA control current. Complete Ikniter circuits have been fabricated and tested for both their dc and transient characteristics, ihe latter of which was done using a Josephson sam- EC-5 pling technique. By using a high-speed step as an analog input, and changing the dc bias of this step, the small-signal transfer function of the limiter wu measured througSioiK ihc AN ON-CHIP SUPERCONDUCTING CLOCK WITH TWO MODES, G dynamic range of the circuit. Experimental results along with details of the circuit design S Lee, R D Sandell, and A. H. Silver, TRW Space and Technology Group - and testing techniques will be presented. A superconducting clock based on a 2-junction SQUID flip-flop with feedback Is presented. The feedback consists of transmission lines that •Supported by the AF Contract F1962S-86-K-O033 with RADC finded by SDIO 1ST. emanate from and return to the SQUID, the entire clock is built as a compact integrated circuit. The period of the clock Is mainly determined by the length of transmission line and there are two modes EC-2 of operation that can be separately excited whose periods are in a ratio SPEED-LIMITING FACTORS IN FLASH-TYPE JOSEPHSON of 2 I l-v data for a pair of clocks with different designed periods A/D CONVERTERS*. Emerson Fang and Theodore Van Duzer, Electron- confirm the presence of the two modes, show how period depends on ics Research Laboraiory, U. C. Berkeley, 94720 - Many flash-type Joseph- length, and give information on the switching time of the SQUID flip- son A/D conveners have been proposed. The majority of these designs flops have been targeted for wideband-signal and low-bit-accuracy applications; therefore, speed is the most important specification. We have studied several types of A/D convener to determine the particular factors that limit EC-6 r their speeds. These have included one based on the seL -gating-AND cir- JOSEPHSON SHIFT REGISTER DESIGN AND LAYOUT,• John X. cuit, for which we have previously reported experimental results, the CLAM circuit developed at NBS, and some new designs aimed at avoiding PrijrbjrsE and I. D. Blaugher, lestinghouse RAD Center - An the limitations of the earlier circuits. We will discuss the dynamic factors integrated circuit chip was designed for a Jostphson shift involved in the various types of comparator circuit. The upper limit on register circuit that simulated operation at 25 GSs using the bandwidth of the various A/D conveners as determined by simulation spans a wide range. Knowledge of the limiting factors facilitates rinding SPICE program. The 6.25 mm square chip featured a twelve-gate, faster and more optimal designs. four-stage shift register fabricated with Nb/AlDx/Nb Josephson *Supponed by the AF Contract F19628-86-K-OO33 with RADC funded bv junctions with a design value of 2000 A/ca**2 critical current SDIO 1ST. density. SUPERCDmTACT, a general program for the design of monolithic microwave integrated circuits, was used to model the EC-3 effects of layout geometry oo the uniformity and phase A FLASH JOSEPHSON A/D CONVERTER CONSTRUCTED coherence of logic gate bias currents. Gate bias resistor! WITH ONE-JUNCTION SQUIDS H. Ko, Hewlett Packard Laboratories • were treated as resistive transmission lines. A layout A novel approach to the construction of a flash-type Josephson A/D con- geometry for the superconductive transmission lines and thin verter is presented. Simulations show that one-junction SQUID compara- film bias resistors was developed. The original SPICE design tors can have a greater than five fold advantage in bandwidth over the was acidified as a result of these calculations. The S- two- or three-jura ion SQUIDs in an A/D circuit. Assuming a Nb junc- paraaeters indicated that bias current variations could be tion technology, a 4-bit A/D converter using one-junction SQUID com- limited to 3% for all possible logic states of the shift parators could have a sampling rate of > 20 GHz with an analog signal register, and phase coherence of the gates could be maintained bandwidth of > 10 GHz. Detail analysis and simulations of an A/D con- verter constructed with one-junction SQUIDs will be given. Further to within 2 degrees at 10 GHs. Preliminary tests of the four- improvements can be made by using a coding algorithm which requires st&ge shift register will be presented. 2n-I comparators, instead of n, for a n bit A/D convener. •Supported in part by AP Contract F10628-85-C-0I58 with RADC. Referen EC-7 1. S.Sa A FAST JOSmSOM SPQ SHIFT MGISTD, P. Kuo, s. R. Whiteley, and S. H. Paris, KYFXBS, Inc. - A fast Josephson shift register has bMn dcaigzwd and fabricated in alL-Mb technology. The aaln data latch is DC biased and operates as a non-latching gate; the data storage is acccssplisbed through the transfer of a single flux quantua in or out of the SQUID superconducting loop. Due to its non-latching nature,, it has the advantage of using a two-phase sinusoidal clock with offset for a wide frequency range. The potential operating frequency goes beyond 70 GHE as verified using a circuit simulation prograau Also, it is a single-rail systea, and no coapleaentaxy input is nneded. Kach stage of the circuit consists of only two two-junction SQUID*r one datn latch and one buffer gate. The buffer gate provides sufficient drive capability and can also be used as a readout gate; hence, no extra readout cir- in the text. cuitry is required. However, to achieve data Multi- plexing, additional gates can be added for parallel readout receiving data directly frcai buffer gates. The operating Margin is estimated to be over 20%. In this papaer, the circuit operation and similation results will be described. The experimental results will also be discussed. EC-8 PLUXON SHIFT REGISTER, Shigcki Sakal. l-I-ii Unezono, experimentally. The ahift register has 16 gates in a long ill length larger than that of the remaining part of the long Signol (b) Josephaon IC technology. Joaepheon Junctions with lOkA'cra" critical current density were made by NbV/HgO/NbN layers. The width of the 1 oner Junctions Has & «3 Lim And the IntervalB between by Au-In film. Successful operations have been demonstrated by Deans of \1) a •Josepnson sampler and (c) an ordinary low speed sampler showed that tansferred data was certainly a single fluxon and the operation speed was very high. The low speed Flg.2 (a) A top view'or the fluxon ahift register, including two gates. operations were done as expected, namely, for exa-nple, when H -2.5. w -2.S. w,-3-5. w^-l.o, W*-2.5, X -3C, X "10. 1 -6.0, W -3.5. dJ-0.5. 8,-0.5. wd -0.1rand d^-0.55. TIME (38.7ps/Div.) clocks (16 gates / 2 phases). Units are In \m. tbl Cross section on the line A—A in Fig.2U). (cl Cross Bection on the line B-B' in PLUIOM SHIFT RRGISTDt Fig.?(a). Josephson sampling. Shlgeki SAKAI, Electrotechnical Laboratory. JAPAN A fluxon shift register* suitable for a memory element of high speed EC-9 digital signal processing, is fabricated. A NOVEL TERNARY LOGIC CIRCUIT USING JOSEPHSON JUNCTION. M.Morisue, K.Ochi, and M.Nishizawa, Saitama University ~ This paper proposes a novel Josephson complementary ternary logic of a part of the shift register, including two gates, and Plg.2(b) and (c) circuit, named as JCTL. Most o£ logic circuits using Jofephson are the crone sections on the line A-A1 and B-B1 in Fig.21a), respectively. junction which have been developed operate in binary form. However, Josephson junction has a tri-stable-state of switching, (2) an inductance per unit length larger than that of the remaining part of that is the state of switching in either positive direction or the long Junction, ordering a potential well to the fluxon losing ite negative direction, and no switching. This is because the kinetic energy, and <3> a bias current terminal for driving the fluxon junction has a symmetrical current-voltage characteristics. rest ing in the well. Utilizing the tri-stable-state characteristics we can make a A sai&ple is designed for Josephson saiDpling measurementBi as shown In Josephson logic system in ternary form, A JCTL proposed here is Flg.l. It conaletB of the shift register, two fluzon pulBer-B "A" and "B", constructed by combination of two SQUJDs, one of which is and a sampling gate Junction. The pulser "A" Is for Inputting data to the switched in positive direction and the other in negative direction. These two SQUTDs operate in complementary form, 82Vpi ing gate Junction. Each pulser has one gate whose strueture is the sane producing an output of logic "I" or logic "-I". The JCTL can as in the shift register. perform several functions such as AND,OR,NOT and DOUBLE NOT. The Josephson Junctions with 1OKA/cm critical current density are oade Moreover, it enn achieve an operation of a Full Adder by only by NbN/M«O/NbN layers. and tb,e width of the long junctions is 2.5 \m. The ad lustinc their current—volt*iHe cn&fcicterLsticti to respective shunt resistors of o•Ox 3 • 5 |^i arc formed by Au — I n film with 1 • •? ohm/E3 . functions without changing the configuration of their (See Fig.21a).) Pb-In-Au films are placed on the NbN counter electrode and fundamental circuit. In this paper, the principle of JCTl. is S10 insulating layer In order to oake the above mentioned potential vella. described in detail and several logic circuits using JCTL are (See Fig. 2(b) and {c).) The intervalB between adjacent two gates are 30 inn• presented. Our Ing one cycle (100 ps) of the josephson samplIng operations, a set In order to investigate qualitatively how the JCTL is able to perform these basic functions, the computer simulations have pulse current 1 is supplied to one edge of the fluxon pulser A . Its been made. The results of simulation show that the delay time pulse height is larger than the critical current I _, causing a single of sum si rcui t is about 3ops/sx.£ioe with power consumption of fluxon, or data 1 , to be trapped at the gate in the pulser as reported in 0.9uW/st«ge. The advantages of JCTL in comparison with the Refi2» The BubseQuently supplied pulse I drives the data 1 to the conventional binary Jose prison logic circuit are (a) simple to shift reglBter. This driven data and the pulse I , which la set f,be construction with small number of elements, (b) a high density smaller than I and Is supplied simultaneously with the pultte 1 , of circuit and (c) consequently a high speed operation. the first gate. Next the shift register la powered by a two-phase clock where pha.te 1 is the pulses T - and I ^ &nd phase 2 is I and ^ hi * and thus data is transferred, step by step, to the adjacent gates. The data A Novel Ternary Logic Circuit tracptd at tne final gatt 1» arlven By cut oulae I , ^^tracttd rro» the Using Joseph:" jn Junction rcffistfr and suoolled to the Ba&Dlmtr ffate lunCvlon- l IB (liven tosetber with I in order to activate the fluxon pul&er B , which Bupplles a 3anip 1 er pulse to the sampling gate Junction. M.Morisue etal. Saitama Universily, Japai of an ordinary low speed pulse measurement.^, where the sampling ^ate Fig.l shows the equivalent circuit of losephson complementary found that It operated completely as expected. This means, for exaiopie, that ternary logic circuit(JCTL) proposed here. JCTL is composed of when aerial-in data "01101101" la Inputted In the fluxon pulser, the sane two SQL'IDs which operate in conplesaentary mode carh other. The (lo gates / 2 phases). The detail of the operation will be preBented in the conference. 10 A )u:;r[lismi Tei rim y Assci i;n i vi- Ncmitrv < el 1 Fig. 2 shows the results o( simulat uiri for t he purpose of •i.i 1. Fig.l r\\ r\\ r\\ . "LOLOLZZSLOI o be urltTi or mre I i i J _„• J •1 »\ -too I Mf M for rtxlm :» o - •- fig. I Sttte oi SailDj ' Outputdout) Iwr SOUID A Low SQUID t NO SKitchinc No Mitchiiw Locic'O' Sditdiinc in No »itchiw locfc'l' poaitin direction Ko snitehliK Snitdiliw in Loctc'-l* Mcativa dlrtction S«itchirn in Svitctiim In Don't ear* EC-11 matin direction positive direction QUANTim FLUX TYPE LOGIC CIRCUITS UTILIZISG JOSEPHSON JUNCTION TRANSMISSION LINES. M.Morisue, H.Sato, and K.Araki, Saitama University — A new type of logic circuit with very low dissipation loss is proposed which uses Josephson junction transmission lines. In this scheme, information unit is carried by quantum flux soliton wave called fluxon along Josephson junction transmission line. Biasing currents can control a EC-10 propagating direction of soliton and even a preservation of it, A JOSEPHSOH TERNARY ASSOCIATIVE MEMORY CELL, which will be utilized for threshold characteristics in logic H.Morisue, K.Suzuki. Saitama University — This paper describes operations. By our computer simulations, "AND" and "OR" a three-valued content addressable memory cell using a Josephson operations with two input have been confirmed of which circuit complementary ternary logic circuit named as JCTL. The memory configurations are very simple. Further sophisticated logic cell proposed here performs three operations of coincidence, circuits, e.g. full adders, will be realized with relative ching simple circuit topology. function, in addition to the conventional memory functions of writing and reading in ternary logic system. The basic memory cell is constructed with a superconducting EC-12 loop in which stores quantized persistent circulating current 30SEPHS0H-3UMCTI0N BALANCED COMPARATORS: flowing in either a clockwise or a counterclockwise direction DYNAMICS AND FLUCTUATIONS, I. N, Askerzade, V. K. corresponding to a logic "1" or "-1". No circulating current in Korncv, V. K. Semenov, and V. 0. Shchedrin, Moscow the cell represents a logic "0". 5t 11 uns) ana divider I 7"i> j miri i <*(••> J . ( ."-li devlrp prurt-i« <• current resolution is predicted to equ DVNflHICS AND FLUCTUATIONS I. N. Askerzade, V. K. Kornev, V. K. Senwnov, and V. 0. Shchedrin Depurtnent of Physics, Moscow State University, 119999 6SP, Moscow, U.S.S.R. Use of the Josephson junctions (inste»d of the traditional Esaki diodes) in sampling comparators has resulted in a drastic increase of sensitivity of the samplers together with a noticeable Improvement of their time resolution [1-3]. Nevertheless, sensitivity of the reported Josephson junction samplers is apparently far from fundamental limits and is determined by "technical" fluctuations of the sampling pulse amplitude and the dc feed currents. The purpose of the present work was to approach the fundamental sensitivity limits of the samplers by replacing a single Josephson junction used in previous versions of the device by a "Goto pair" [«] of the junctions. These twin junctions are connected in series for the sampling pulse current (unit dc feed current) and in parallel for the Kasured waveform current and the feedback current. As a result, for Identical junctions the contribution of the sampling pulse amplitude fluctuations and dc feed current fluctuations to the noise of the whole device becomes much lower. In this report we will present a detailed analysis of dyna- mics and fluctuations in the balanced comparators using: EC-14 EXPERIMENTAL STUDY OF THE RSFQ LOGIC ELEMENTS. V.K.Kap- i) overdumped and ii) underdumped junctions. Although the dyna- lunenko*. H.I.Khabipov*. V.P.Koshelets*. K.K.Likh«rev+. O.A.Hu- kh»nov+, V.VL.StMnov+, I.L.Serpuchenko*. A.N.Vy*t*vkin*. * Ins- mics for these two cases is quite different, at least one impor- titute of Radio Engineering and Electronics, + Hoscow State Uni- versity - An integrated nicrocircu.it including new elements of tant relation (see Abstract) has been found to be common for the recently proposed Rapid Single Flux Qtianttin logic family has been developed, fabricated and studied. The circuit contain- them. ed a trigger flip-flop and converters of digital information from the usual potential fora to the SFQ form and vise versa, interconnected with discrete Josephson transmission lines which transfer and wplify the SFQ pulses. The structure has been fa- References: bricated using a 5 am Nb-A10x-Nb tunnel junction technology with the critical current density about 500 A/cm3. The external 1. P. Ho If, B. J. Van Zeghboroeck, and V. Deutsch, IEEE Trans. Ho thin film shunts overdanping the tunnel junctions 12 Session MC NbN, Nb3AI, and Nb3Sn 2:00-4:30 p.m., Monday, August 22,1988 MC-1 MC-5 Nb3Al FORMATION PROCESS OF POWDER METALLURGY PROCESSED WIRES AND SPUTTERED MULTILAYER FILMS, *K. Watanabe, K. Noto, H. Morita, H. Fujimori and Y. :JLjf'fc.Hl.\!N;;'..'w^'J f.'U^iFT: (•;:•" ;n !a'» AM; t'N HUMS. Muto, Institute for Materials Research, Tohoku University-—Reaction mechanism between Nb and Al regions in Nb-Al system was examined using J'-j^-'J K...-V, L'.S.S.H'. - T-iU .'inc.1 Vf,~ I'lir.a L^^st*ss:ri»; 'i sputtered Nb/Al multilayer films and powder - 1 ne*. l;Mi^:t. l-.-ii Kd;> f).t?l-^t.?'J •;. 2>1 .'J-.1 = i1 .')-Jt!.... , metallurgy processed wires. It turned out that at H1 sirif-it pn.isf specimens we;v •'.i-.r,'^ dt parMa: pr-ai Nb-6wt.t Al composition, the formation of NbsAl t ;_• V V , - i -t? and but?^l !3 It.1 te*:nfjt'riitur<* u!" t'JO processed by multilayer films was very different 'OO^'L. r:el*l 'if pr nJt?:u *.- of tri-= vjliiiay pi fining foivi? j^ from that of the wires processed by powder that flux jUti^l^^ is Jue to ele^.ivn SLatterlry, jt { metallurgy. Especially, in the multilayer films L :.-.'. . ~ H ' P" i(;-!=l-, A n^xinur: pinrung ror-.u WHS with the Nb layer thickness of 1500 A which ,^[Jtvsl*i:iteiy ^ '>0 ' N r.\" :\.-r ",,>U. (Ut;h atanillty u!' corresponds to the effective Nb filament size in :ii"i:; li. Jiic :•.; Lr:in ^rvty. 11 VH layer a! l*i^ surl'jct- powder process prepared with the large arial , ur:1.i- t-'-fif? tfar.-sit.ion smearlrij? in niaj^mftli Mela was reduction raio of around 105, the A15 phase was impossible to be formed by the two stage heat . lt-t.L :ui- WJII i'ree fjathJ ds we.- .'ii By diEenslytia: M treatment. On the other hand, we have already obtained the sample with the critical current density of Jc * 10« A/cm* at 10 T and 4.2 K even in the Nb-3.6wt.% Al by means of powder process. In this paper, we present a nodel of the reaction MC-6 mechanism for NbjAl and discuss on the diffusion SHORT-RANGE VARIATIONS IN MAGNETIC HYSTERESIS LOSS OF reaction in Nb-Al system between the powder MULTXF1LAMENTARY Nb3Sn, R. B. Goldfarb. National Bureau of metallurgy processed wire and the multilayer film. Standards; D. B. Smmchers, Teledytie Wah Chang Albany; and M. H. Sceeves, Massachusetts Institute of Technology — One Mthod for measuring amg.netlc hysteresis losses In nuLtlfLLamntary superconductors is with a vibrating-sample magnetoneter. A MC-2 feature of this nethod is chat it requires only snail samples. A15-Nb,Al SUPERCONDUCTORS PRODUCED BY INFILTRATION AND For aeasurements In transverse field, the composite wire Is ALLOYING, W. Schaper, H. Kehlenbeck. 1. Zimmermann. and H.C. threaded onto a plastic screw sanple holder, and the field is Freyhardt. institut fur MetalIphysik. universitat G&ttingen, applied along the axis of the coiled swple. (For tft>3Sn, the 0-3400 Gfittingen, FRG - Nb,(Al,Si,Bi) and NbjAl superconduc- wire has to first be reacted on a steel screw vith Identical tors were successfully fabricated by an infiltration and a thread pitch.) Typical screw dtaaeters are 5 and 8 OM, and the laser-beam process. For infiltration, Nb powder was compacted, sanple colls are about 1.5 cm In height. By etching soae sanples in dilute nitric acid, we have checked that, even with sintered and immersed in a liquid (Al»(,Sii • >h.Bi, alloy. Subsequently the infiltrated rod was deformed and reacted at the nore tightly wound sanples, the NbjSn filaments are not elevated temperatures. The microstructure and the supercon- broken. Ue calibrate the nagnetoaeter with N£ vire wound in ducting properties have been studied in dependence of the the sane geometry as the superconductor samples. Maxinun applied fields are typically Z.U HA/ro (3 T In free space). In degree of deformation, q, and the reaction temperature, TR. this paper, we report on variations In hysteresis losses for The critical temperature, T^, ranged from t4 to 18 K, upper contiguuus sanples of nultifilanentary fft^Sn superconductors. critical fields. BC2, of 21 T and critical current densities, a 1 Wires aade by both the bronze process and Sn-core method were Jc. f 10* A/cm at 16 T were obtained. examined. Even though the samples were nominally identical and The continuous COj-laser-beam irradiation {laser power s 4.5 reacted simultaneously, differences of 10% in losses are kW) was performed on Nb-sneattied Nb-25 at.% Al composite tapes comnon. These variations cannot be explained by imprecision in prepared by a conventional powder metallurgical method and calibration or other measurement conditions. Ve attribute the moved with a velocity v £ 30 m/min. The resulting metastable differences to lnhomogeneity in wire characteristics on a scale bec NbAl solid solution was transformed into near stoichio- of less than a neter. The variations are somewhat greater In metric Nb.Al with critical temperatures of 18 K and Jc = Sn-core sanples reacted with short welded tails, as compared to 10'1 A/un- at 16 r. samples with long "cold tails". This work was supported by the Department of Energy. MC-3 Fib.A] POWDER METALLURGY PROCESSED WIRE RAPIDLY QUENCHED MC-7 FROM HIGH TEMPERATURES,* C.L.H. Thleme, S. Pourrahimi, and INTERMEDIATE SCALE INDUSTRIALLY PROCESSED Hb.Sn(Tl) BY S. Foner,+ Francis Bitter National Magnet Laboratory,++ and J Plasma Fusion Center, M.I.T., - Caabridge, HA 02139 - Rapidly POWDER METALLURGY,* S. Pourrahimi, C.L.H. Thleme aod S. Foner,+ quenched powder aetaLlurgy (P/K) processed Nb-Al wires were Francis Bitter National Magnet Laboratory,++ and Plaan* Fusion fabricated starting with stolenlo«etrlc Nb-Al powder mixture* in Center, H.I.T., Cambridge, MA 02139 - Our powder metallurgy a Mb tube. Processing Involved consolidation, hydrostatic processing of Nb Sn(Tl) van scaled up to 75 ma rfia. billets each extrusion and wire drawing. The wires then were heated for a few containing 4kg of powder composite. Prealloyed Nb-1.5wtXTi powder seconds close to the oelting temperature, T , and then rapidly was used for optimum high field properties [1), An Initial hot quenched. For T 13 discussed and improved analytical expressions for the calculation s critical temperature of about 11K van obtained. A careful of loss** ar* given. The results of numerical calculations are structural analysis (SEM and X-ray) of the- saicplca was [*f compared with aeasurvacnta of hysteresis losses in •ultflla- formed. From the measured p IT) and Tc an cxtinatc of the BI dentary wire with hollow filaments. face resistance ta inferred and compared with that of the Niobium. MC-9 Ho-Re SUPERCCHDUCTWG THIN FILMS BV SINGLE TARGET MC-10 HAGWETUCK SPUTTERING, A. Andreone*, A. Barone**, A. Di THE INFLUENCE OF TRANSVERSE. COWRESSIVE Chiara", G. Haicolo*, v. Palmier!*, G. Peluso*, U. Scotti di STRESS ON THE CH1TICAL CURRENT DF MULTmLAJCWTARY NbgSn WIRES, - K. Boschmmn. H. H. J. ten Kate and uccio*, • Dipartimento at Scienze FiBlciie, UniversitA di L.J.M. v.d. Klundert, University of Twente. The Napoli, Fiaxzale V. Tacchio, and INFN, Pad. 16, Hostxa d'Ol- Netherlands.- The effects of axial stress on the Utairt, Napoli, Italy; + lotituto di Cibernetica, CNR, Ar- current conducting capacity of NbjSn wires have been co Felice (NA), Italy; t Dipartiaento di Ingegneria del Ha- studied thoroughly during the last 15 years. It tarlali e della Produiione, University di Napoli, Napoli, turned out t hat t he cr 111 cal current Is very Italyi x INFN, Liberatori National! di Legnaro, Legnaro (PD) sensitive to this kind of stress and strain. In magnets both axial and transverse stresses on the Italy - The use of superconducting thin films in accelerat- wlnd1ngs occur due to Lorentz force. Alt hough 1 n ing cavities is certainly one of the moat stimulating per- magnet design the Influence of both effects on the spective of application of superconductivity to fundamental MAXIMUM current should be taken Into account, the research in physics. Mo-Re alloy is great of interest in thlB latter phenomenon has not (yet) been studied very context. Among A-15 Materials Ho-Re has a lower sensitivity well. Recent research on this Issue, however, shows to radiation damage. Moreover the high T phase can be rea- that transverse stress aay cause an even mucn larger c degradation of the critical current than axial stress lized out of equilibrium at relatively low substrate teape- does. We Investigated the superconducting to normal rature although the maximum Tc reported is only achieved transition for aultlfilaaentary wires as a function above 1200 °C. He realized Ho6DRe,,0 and Ho75Re35 thin films of appl1ed field and transverse coapress1ve stress. by single target magnetron sputtering. The deposition tempe- Special attention was paid to the analysis of the rature was varied between 100 °C and 1000 °C. All the films measured voltage current characteristics, which show showed a sharp transition and T values up to 13K were the Influence of geometrical factors and the change c of t he 1nner «t ruet ure of t he coapos1te under acMaved. At relatively low substrate temperature (t ~ 400°C) transverse pressure. Session LC Stability I 2:00-4:30 p.m., Monday, August 22,1988 roolni suprrrmidurt inn cui 1 wilh a cable in romfu if i ype LC-1 conductor fcot's normal, (he pressure inside I he ronling p rises r.ipully, lierause <>t l tie typically small hydraulic CALCULATION OF NORMAL ZONE PROPAGATING VELOCITES diameter of the flow path The s.ifety oi the roil and Th AND TRANSIENT THERMAL EFFECTS DEPENDENCE ON THE SUPERCON- facilities depends on the IHYS^UIC rise in tlie worst i-.is DUCTING WIRE PARAMETERS, J Cans and L. Rinderer, lnstitul de investigated experimentally the pressure rise insitie (tie Phyiique Expe'riracntile. Universile de Liuisnne. CH-1015 Lsusanne. conduit simulated the conduct"r lor pratt nal tise durtiiK Switzerland - We hive investigated experiment illy ind theoretically quench, and compared the lest results with I he Killer's The normit phise propagating velocities along superconducting wires thenntical equations 14 LC-6 properties or the windings. The applicability of the results PRESSURE DROP HEASUREHF.NTS ON SUPERCRITICAL HKL1UH COOLED CABLE [S CONDUIT CONDUCTORS, H. A. Dsugherty. V. Huang •This work 1B supported In part by Grant in Aid for Scientific and S. U. V»n Sclver, Applied Superconductivity Center, Research, Ministry of Education in Japan. University of Wisconsin - Forced flaw cable in conduit stability aarjiins at the price of high frlctlonal lo»see and large pumping power requiresents. For extensive projects such LC-11 as the International Thermonuclear Experimental Reactor design si AH I l.i /.M I i)K oi- r I CIITI.V wursu siii'iiw (wnuiT! Nt; nkv c oo pc rat Ion it is essential to Icnow the p ressure drops to be SUI.KN'tHIS M UH.VIA. A*il) II HAfcllA TOSHIBA RKfl (TNTKH. K-m.is.tki expected from different conductor geometries and operating J.-i|i.iti A-i w.is sny;v;»'»l«'it m thr picvinu-. /MIX-I iiulrnt ml cond It ions * To oeasu re these tires su re d roDS a flow loop was pnti r-ilur.s In M dlu I r/<< 'It v MI I ITO ids without i»ol.fiti < tui Is. t! i r f t? tren t conductors* The loop l& surrounded by a J ^ M^iri'ssiun in lh<- <'HI windinc .in L w^r khi'<'t*« hi'lwi'v'it l.iyor ' Sludii's on (ht s* Bt't hod'r ^arf teiperatures. A coll heat exchanger iaaersed In a heUua bath Is used to renove the heat generated by the puap. Pressure I'.isr to Kj(|»*"i iMt'fit on .i •orii'l • LC-S densities near 70 kk/cm, but there was no apparent difference QUENCH DETECTION OF SUPERCONDUCTING MAGNETS USING between the Insulation types as far as training behavoir was ULTRASONIC WAVE,*** A. Ninomiya, K. Sakaniwa, H. Kado, concerned. T. Ishigohfca ISeikei Univer&ity), and Y. Higo (Tokyo Institute of Technology) - A method to detect a quench of a supercon- ducting magnet using ultrasonic technique is presented. This method utilizes a change of acoustic transfer function of a superconducting magnet induced fcy a local temperature rise or an epoxy crack etc.. Some experiments are carried out on a small epoxy impregnated magnet. One piezoelectric element (driver) is attached on the top of the magnet, and the other element (receiver) is attached on the bottom of the magnet. • Supported In part by the NSF thru Grant No. PHY-8611210. The injected acoustic wave by the driver travels through the magnet, and received by the receiver. It is modified by the acoustic transfer function of the magnet. The acoustic LC-14 frequency spectrum of the receiver signal are affected by disturbances in the magnet. This phenomenon is observed MEASUREMENT OF AC LOSS IN Nb Sn through an experiment using a pseudo-random noise with wide 3 frequency range. The received signal is processed digitally SUPERCONDUCTORS,' M. Takayasu, S.H.Autler, C.Y.Gung, using a FFT analyzer. The experimental results show that a M.M.Steeves and M.O.Hoenig, MIT Plasma Fusion Center • local temperature rise of about 2-3K can be detected by this Substantial AC loss is expected in multi-strand, high method. current density, cable-in-conduit, commercial NbsSn superconductors. The objective of the test program is the ***Supported by Grant-in-Aid for Co-operative Research of the measurement of the AC loss of US-OPC wire in magnetic Ministry of Education» Science and Culture of Japan. fields with triangular waveforms of maximum range from 0 T to 10 T back to 0 T in 12 seconds. The dominant LC-10 components are hysteresis loss and coupling loss within a INSTABILITIES OF IMPREGNATED WINDINGS INDUCED BY EPOXY single, multifilamentary strand and coupling loss between CRACKING, *T.Yamashita, S.Mshijlma, K.Takahata, T.Okada, strands in a multi-strand cable. Ramp rate, background T.Fukutsuka-t-, K.Matsumoto+. and M.Hanada+, 1SIR Osaka field and transport current profile are important variables . University, Ibaratci, Osaka 567, +Kobe Steel, LTD., Kobe Hvogo With the sample located in a G10 liquid helium container, 651 — The change of the mechanical behavior and the superconducting instabilities of impregnated windings induced AC loss is measured as a function of He boil-off by the by epoxy cracking have been studied In order co establish the calorimetric method. The flow meter is calibrated by methodology of the constructing the stable superconducting means of a heater, located in the proximity of the test magnet. Epoxy cracks are inevitably induced In Che process of sample. Several 12m long single strands have been training. "the cracks cause the degradation of the rigidity of the superconducting windings and hence the evaluation of epoxy measured with and without transport current at ramp cracks in impregnated windings is important in analyzing the rates up to 1.67 T/s and peak fields up to 10 T. While the stability or Che windings. The test windings in which epoxy work continues, the paper describes difficulties cracks are Introduced purposely were used and the degradation encountered and relates preliminary results to the and the training behavior were measured before and after the literature. iKea5ured by strain gauges. The introduction of Che mechanical defects was also detected b v the A E • &cnniciu£Si Before the crack introduction the winding showed the training that is the quench current Increased with quench number. After the crack introduction the quench current did not increase with quench • Supported by DOE Contract DE-AC02-78ET-51013. 15 an exact Holution, Is preeented. The model la baaed on an experimental observation that resiBtivity of QUHCHUG or MULTISKSKM SUPIRCOHDUCTLKC MAGWTS matrix in a good approximation la proportional to fITH mm AID JtXTOIKAl SHtmi RtSISTOAS. A.A.KonJu- apeciflc enthalpy of winding in the temperature khoT, Y.A.aalglaoT. V.V.aatokhln, V.R.Karaalit, L«b«- range from 30 to 300 K. By using this model the im- dar Ibjralcal Inatituta of th« Acadaay of Sci»nc«a portant parameters of quench were calculated. The of tha USSR, Moaoow. Quench protection by miMivl- measured electric voltage inside winding and current •lon tachnlqut with uaing of insar and axtarnal load ware found to be In a reaaonable agreement with •hunt raalatora m invaaticatad. Temperature rlae theory. The used subdivision technique provides a In varloua plaeea of wlndinga "•• aaaaurad by »ol- reliable protection of coil* in which the parameter derad to the wire tneraocouplee. Il>e dlacraa* eha- Ej2 exceeds a value 1O23JA2/m*. ractarialng the normal zone propagation along radi- al and axial direction* were obtained. Initial cur- rent varied froai 0.3 up to 0.9 I . The efficiency c OUANTIFICJTJUK OF DrsTUKBAKCE ENERGY DUE TO CONDUCTOR of eutnoh protection by aubdlvialon with external HOTION AND STABILITY ANALYSIS OF SUPERCONDUCTING COMPOSITE HIKE. ahuata dapenda on the nuabar of aectlone and It ln- * T. Takao, S. Honjoh, and 0. Tsuhaaoto. Faculty of Engineering, creaaae aa aincle aeotlon dlaanaiona decreaae. Yokohama National University - The aost intricate disturbance ataunta being placed Into the magnet winding cauaa causing a quench in n high-cur rent-density superconducting rjuenoh anohancaaant and conalderable falllnc of the eagnet is an abrupt conductor notion. There have been very few Tlii» teaperature rlee. The paaalve technique of papers investigating disturbance energy of the conductor notion aubdlTlaion with Inner ahunt realatora le realized and it is generally understood that its quantification is very for the flrat tiaa and can be recoaaended for uaing difficult. We have proposed a nodel to quantify the disturbance In large auperoonductlng aagaeta* disturbance energy to aechanicnl properties of a conductor, £*^CLr0a*aBn£tic torcp flftii w I n u t n B structure* Wp fter.oriDPu expermems to verify the Bodcl, We simulated a conductor •otion QUITCH PROHCTIOH OF SUnRCOMSUCTIXS JUGXMS WITH with a pneumatically operatpd apparatus and Measured disturbance HIGH CUUUK DUBITy, V.S.Vyaotaky, V.R.Xaraaik, energy by measuring the temperature rise and displacement of the a.A.Konjukhov, A»IiRuainov, Labedev Phyaical Inatl- tute of Acadasy of Soianeee of the USSR, Moacow. conductors are presented and measured results are compared to for protection of euperconductlng aagnete with ove- values calculated fron the node!. Based on our model, stability rall current density J > 10 A/a and atorage energy of a superconducting coepositr conductor subject to an abrupt 1"%1.5 MJ a paaalve technique waa uaed - a aubdlvl- conductor notion is invesiifiBtpQi aion of winding by low ohaa ahunt reeiatora. The *»- xiauai nuaber of aectiona reached 40* Kxperlaental reaulta of quenche* are dlaouaaed. The aatheaatical •Supported by Grant-in-Aid for research, The Ministry of •todel of quench of superconducting aagneta, allowa Education, Science and Culture. Session MD High Tc Superconductors: Bulk Processing I 3:30-5:30 p.m., Monday, August 22,1988 Sintered superconducting materials were encapsulated in in MD-1 evacuated stainless steel or pyre* glass containers and processed in a HIP unit al high temperature* and pressures. Optimum HIP conditions EFFECT OF ALLOYING ON THE SUPERCONDUCTING PROPERTIES to obtain bvlk samples of nearly theotetical detuity were dcletmincd. ErB*2C«3O SYSTEM. C. S. Faade. A. K. Singh, H. A. Hoff. M. S Osofsky. 7 Resulis indicate that ifl addition to density, HIP also improved T M. A. Imam. K. S-daMidt Bid L. Rickards. Naval Research c Further more, for the 1-2-3 system. Ike grain me is significantly Laboratory - Clote examination of the grain bomdaries ia the 1-2-3 reduced during HIP and is attributed to fraciuring of course particles system hai revealed (he presence of i noa-ivpercoadNCiiiig phuc in ike sintered compact due to high strain rates experienced during The tddilkM of low Mclliag oxide* of BJimuth or Indium nelili which the presiurizatioo. Since the microcrack formation in these bridle have Ike me vaieacy tad aearly the tame aioaic iize ax Er could materials is expected to vary with grain size aa (d)- W*, decrease in legregsie to the grain boaadariei and poitibly mppreii the grain size is expected to increase significantly (he toughness of these foraatioa of aton-tKpcrcoHdBcling pliaiei at the boindar.es and materials. HIP mMertftU can be machined lo any shape and sire and is hesce ia-prove ike coHdiclioa scroll ike boundaries. Likewite it is being tied for making specimens for S measurements and kaowa that ike wall addition of Boron will help intergranular c superconducting devices. cokeiioa in many system. Saiall quantitief of these elements were added in their oxide fom to the mulvre of EnO?. Bi^CO^ and C-0 and ike iipercoadnctiig 1-2-3 cotapoind was prepared by the norm*) solid stale reaction. In a separate experiment a mixture confining of MD-3 73% of 1-2-3 aad 25% of Bi-Sr-Ca-Cf-O compound, were prepared PROPERTIES OF HIGH-TC OXIDE FIBERS MADE FROM LASER together to evaluate combined effect on tke properties. Addition of HEATED PEDESTAL GROWTH R. S- Feigelson, D. Gazit, D. Fork. J. 0.05% Bi increased tke oniet of Tc from 93°K to IO5°K while ihe RD Z Sun, T. H. Geballe and A- Kapitulnik, Slanford University - The remained aocbanged at 92°K. On the other hand, the addiiioo of In and B had no effect on tke mpercondicling stale. Similarly the fine-fibers offer a possible route for making superconducting cables addition of 23% of Bi-Sr-Ca-Ct-O did not cause any detrimental cffeci of the high-Tc copper-oxide compounds. The laser-heated pedestal on tke «per conduct ing ptopertie* of the 1-2-3 compound. Electron- growth technique which has been developed at Stanford for growing optical evaluation of microslrnclnret of all of the materials were 1 performed to examine the grain boundary structure, the phase incongruntly melting compositions* * seems to be particularly diitribilion, and effects on microtwitning. Results indicate that suitable for making model fibers. The molten zone is narrowly while the tetragonal to oikorkombic transformalion is diffusion defined and is rapUly quenched. The first attempts with this method controlled, the accompanying twining resulting in a tveci type using La2-xSr CuO4-5 and YI^CA^CVS had difficulties due to structure is s martentitic type of transformation. x decomposition and the volatility of CuO. Only the surface skin remained superconducting. The Bi containing compounds however, MD-2 was found to be quite stable during growth. The Bi-Ca-Sr-Cu-O fiber PREPARATION OF DENSE BULK HIGH Tc SUPERCONDUCTING grows in elongated single crystal plates with the c-axis normal lo the MATERIALS USING HOT .SOSTATK PRESSING. M. A. Imam. A. K. Singh. growth direction, which makes it favorable for high conductivity K. Sadaaanda and M. Osofsky. Naval Research Laboratory - One of ihe along the fiber. Experiments to date show resistive transitions of the major considerations in the application of high Tc superconducting materials •> the attainment of high current densities. In order to as-pulled fibers to have a partial transition al 110K with a zero accomplish this in bulk materiili it is important to improve the inter- resistance at 80K. Latest results on critical current measurements grain contact by eliminating all internal porosity in sintered and magnetic studies wilt also be reported. pfodacts We have accomplished this for Ba-Cu-O with Er or Nd. Bi-Sr- Ca-Cu-O and Tl-Bt-Ca-Cw-O systems using hot isostalic pressing (HIP). (1) D. Gazit et al: lobe published. 16 MD-4 MD-6 Bi-Sr-Ca-Cu-0 BULK S -PERCONDUCTOBS WITH ZERO ZERO RESISTANCE ABOVI; 100 K IN Hi BASED RESISTANCE ABOVE 110K. H.S.Huang, S.N.Mao, Z.V.Wu, SUPERCONDUCTORS. " S M Green. " C Jiang."1 Yu Mci." H L Luo1" M.L .Liu, Z.Guo. X.Zhao, Y.Z.Liu, z.L.Huang, J.L.Yu, and C Politis' *' ' "University of California. San Diego, Department of K.S.Zhang, Physics Department, Tsinghua University, Beijing, China - Cutting off the resistive tail of Elecmca) and Computer Engineering. '"'Kerforscriungszrnirum Karlsruhe. Bi-Sr-Ca-Cu-0 bulk superconductors has been t he ob- Institut fiir Nukleare Festkorperphysik. - With ihc discovery of hnjh-Tc jective of much research since the superc-onductivity superconductivity in the Bi-Ca-Sr-Cu-O sys'em. a resurgence of interest in the at 85K and 105K (extropolated zero resistance ) in materials aspect of superconducting phases has occurred Specifically, there this system was reported by Meada et el. We have is clearly & 110 K superconducting phase in this system Yei, resistive and successfully prepared bulk superconductors in the IU- susceptive steps seem always to occur, with zero resistance not achieved until Sr-Ca-Cu-O System with zero resistance above 110K by controlling composition and processing. Experimental well below 100 K. Wp repon ihc achievement of zero resistance well above results show that the onset of transition is 125K, 100 K by slightly altering the composition of the material the endpoind of transition determined resist ively is 114K and A.C. Meisaner effect is about 30%. Sampls shows a good stability. processing, experemental MD-7 results and structural studies will be presented. PREPARATION OF HIGH Tc SUPERCONDUCTING THICK FILMS AND POWER CONDUCTING TUBES BY A IJOV-PRESSURE PLASHA SPRAYINC, MD-5 K.Tachikawa", H.Ono**, Y-Shinbo1™, T.Suzuki**, H.Kabasa«a"*, and S.Kosuge**, *Dept. of Materials Science, Tokai University, PREPARATION AND CHARACTERIZATION OF TEXTURED J **SteeI Research Center. Nippon Kokan K.K.-Superconducting DyLB«2Cu3(>7_£. > Seuntjens, H. Daeualing, X. Cal and D. C. Larbalestter, Applied Superconductivity Center, University of thick films of Y-Ba-Cu-0 systea hive been prepared using a lew- Wisconsin - The Dy1B«2Cu307.6 faulty of high Tc oxides in pressure pUsna spraying technique. The filas in the thickness known Co be anlaotropic in Its physical properties. Due to range of 20-100>UB were deposited on trie Ni-base alloy anlsotropy in Jc, it Is necessary to texture this uterlal tor substrate in a vacuun chamber with a pressure of about 70 torr transport current applications at 77 K. We have prepared (partial pressure of oxygen:40 Torr). The chemcal composition homogeneously c axis textured samples with < 200 UQ-CB resistivity at 100 K and > 90X density by aligning powders In of the deposits was found lo be very close to that of the a iMgnetic field and then sintering. Analysis of the texture spraying powders. After the annealing, filns showed zero by light aicroscopy (LH) and X-r»y diffraction (XRD) will be resistance temperatures of 90K. An proved fil» preparation presented. Longer sintering tines iaprove the texture process, where a Y.Ha,,Cu.fiOx layer was coated on trie y,Bi, TranaalKslon electron microscopy (TEH) and LH were also used CujOx matrix layer by a low-pressure plasna spraying, has been * characterize the alcrostructure of the textured Material. developed. Significantly enhanced critical current densites Second phase, primarily Ba-Cu oxide, Is present in a larger o UBfrer ox s ral n bounoarles t han convent lonally since red have been achieved through this process. In addition, saaples but not detected by XRD. Transport -Tc*s in field show preparation of superconducting thick filas of Bi-Sr-Ca-Cu-0 is Halted Lnprovenent over non-textured saaplrs (~ 10-20 A/CB2 also under way. The superconducting power tubes (outer 1-7 T at 77 K). AC susceptibility and transport neasurewents diameter: ltai, length: 140m and wall thickness: 1*) were still Indicate weak links Unit J£. A detailed description of successfully produced by a low-pressure pltsw spraying. 100- the texturing process and the results of the analysis will be given. 200u* thick V-Ba-Cu-0 superconducting filns were deposited on the outer surface of the Ni-plated Cu tubes (Ni-plating layer served as a diffusion buffer layer of Cu into the film). After annealing for Ihx at 930T, the filas exhibited super- conduccjvi ty vi th Tc of 85-90K. Detailed superconducting Supported in part by Dept. of Energy-Division of High Energy properties of the power conducting tubes will be reported. Physics and Office of Fusion Energy. Session ME High Tc Superconductors: Measurements 3:30-5:30 p.m., Monday, August 22,1988 or micro5tmctunl virittion. and n-vaioes in the range 15-100 ire commonly ME-1 observed. We report mctsurements of resistive transitions at 77K on « scries of YBtjCUjO, wires is a function of applied magnetic field. For electric fields in WH1N0 KOBIN TFSTS O¥ Tr AND t<- ON VlidZCu.ifU * V Kisiur.t*l the range 10'6 Vm'1 lo 10"3 VmJ clear power law transitions are observed with N t!isurhi*1 S MoKUro«2.K Takahashi*2.T Ishih.irj*;t M IW-d.i"! n-vilues in the range 4-30. The n-valuc is observed to fall with increasing *1 SlertrotiThniraJ Ldbor.itory AIST *2 Knmn.'rr INK Hcsf.irch As applied magnetic field and shows strong hysteresis related to trapped flux when the field is cycled. The n-value is related to microstructurc in measurements on wires with different additives, and on a series of wires of different bulk density prepared using viscous processing techniques. A straightforward extension of (Sup»-r ffll *;) Fine (>r«i« IVntpr.*4 Moonlixhl Project Pnt«ot icin the analysis for conventional composites makes it possible to rclite the n-value Off no. AIST. In advance of study on t-ondudni dfvi-lpoacnt ni directly to the standard deviation of the spatial critical current distribution. oxiHe suprrronrjmior. round rnbin tests of fimtl^arntal 17 Gastro. and R. M. Aikln. Los Ataaws National Laboratory - «e ME-4 report on the development of a plaaaa-mrc spray process for in* application of low resistivity silver contact Junction* onto LOU RESISTANCE OHHIC CONTACTS TO HIGH T SITERCONDUCTIWC YBa3Qj30-t sintered ceramic materials. The contact rcili(a»cc» THIN FILMS. Y. TAZOR. K. AI KARA. K. MIYABARA. K? HOHKAUA. and K. decrease momonlcally with decreasing temperature and are OSKIMA. NTT Elactrlcal Communications Laboratories, -- It is typicaJJy <10-*f)-cma at 75 K. ]-V characteriatlca are linear up critically important to control the Interface between high T to a critical current density thai agrees with that of the superconducting oxides and other materials for device applica- underlying superconducting material. Advantages over other tions lucli mm tunnel junctions and superconducting transistors. contact methods Include: amse of application, absence of any We have Investigated the effects of surface treatments before post-processing treatment, and applicability to large areas and deposit ing metals on the metal-high T superconductor Interface. arbitrary shapes. *rj have demonstrated a method for obtaining low resistance electrical contacts to Yb.Ba-Cu.O. superconducting thin films. Au if choien a* the contact mctil because of Its low affinity for oxygen, vhich Is a major constituent of high T films. When Ar sputter etching Is done, the current-voltage curve exhibits •Work performed under the auspices of U.S. Department of Energy typical reverse direction Schotcky characteristics Jn both polarities of current. This suggests that a seniconductar layer exlsta between Au and the higli T film. A contact resist- ivity Is an order of 10 Ohm.cm «t 77*:. SOR-XPS experiments ME-6 shew a large perturbation In Cu-0 bonding states which Is a Ag SCREEN CONTACTS TD SINTERED YBa3Cu,0K POWDER FOR clear Indication that oxygen has been expelled at the supercon- RAPID SUPERCONDUCTOR CHARACTERIZATION. John HoreUnd and 1. F ductivity because the process expels oxygen fro* the supercon- Goodrich. ElfctroiuBn*tic Technology Division. National Bureau ductor surface. These results lead to an Important conclusion: of Standards. Boulder. CO - We have developed a new nrthod for it ia Important to remove the semiconducting surface layer without degrading superconductivity. Building on this pellets for rapid superconductor characterization Ag wire coneluvlon< we have cieve. loped a surface t treatment process In an screens are Interleaved between calcined powder sections and oxygen environment. This process Involves the following steps: then fired at 93O'C to form a composite pellet for resistivity (1) oxygen ion aputter etching, and (2) high pressure O plasma treatments followed by an ln-sltu Au deposition. No perturb- ation In Cu-0 bonding states Is observed. The l-V curve of contacts through the above process shows chnlc like character- istic*. A contact resistivity la remarkably decreased to 5.5 K 10 Oha.c* at 77K. uniformly Injected Into the ends of the pellet through the bonded Ag screen electrodes Also, Ag screen voltage contacts which span a cross section of the pellet, aay provide an ideal ME-5 geometry for detecting voltage drops along the pellet, LOT GOrrTACT-RESISTIVITY JUNCTIONS' TO CEXAMIC comparing surface voltage taps to the Ag screen voltage taps SUPPKCNDUCTURS,» M. P. Haley. J. O. Illlli. J. D. Katz. R. C. will be presented. Session LD Fusion II/MHD I 3:30-5:30 p.m., Monday, August 22,1988 Lufcell, S.S. Chen, Oak Ridge National Laboratory (ORN'L), Fusion LD-1 Energy Div., Oak Ridge, TN 37831.— The Swiss contribution to :lie international Large Coil Task (LCT) is a D-aiiaped 2.5- x KAGJTCTS FOR 150 GHl GYBOTItONS, *W. tourer, m B. Ploaczyk, p. Turowslcf, K«rnfbr*chungszaT)trum Karlsruhe, 3.5- m n bore, superconducting toroidal, field coil of 5 T fit-; :. H. roarittr. ASEA Broun So vert, Nannhaia, and 0. Krlichel, The winding, r.ad? from fully transposed filamentary Cu-stabili Int^ntom Berglach-Gladbach, Federal Republ ic of Germany - led nbTi cables, is cooled with pressurized aujiercrit ical he- The development of thrt* magnet sets for a 150 GHz Gyrotron ilia circulating in a seamless copper pipe on the conductor la described. Two of the sets were already built, tested and used for generation of high frequency waves using the i .1 tne International Fusion Superconducting Magnet Ter.t Faril: gyromotlon of electrons In a magnetic field. The third act Is '.y (IFEHTF) at Oak Ridge National Laboratory, Term. Results of in the construction phase. Problems and difficulties during the development phase are discussed in this paper. Also the reported elsewhere /i, 21. This paper present:; at first the da experience during thn eiperlmtnts will be described. This •a of the ac-losn measurements taken during the Standard-II development of 150 GHz gyrotrons is within the EUROPEAN eats. Die resets will be compared with predictions fca3cd on Fusion Technology Programme and has the ultimate development .li^rt sa.tipl« measurements rain during tiie design of the coil. goal of a 150 GHz gyrotron unit with 1 HH power at steady state operation for plasma heating. (.•set t.);e results of the extended condition test will be rresen *ed- Finally the recently analysed quench data, taken during .. 5. Vecsey et al.. Preliminary Teut Results of the Swiss LT LD-2 Coil, IEEE Trans. Mag. MA^-?3. F- 1697 (1?87). IMPACT OF IICH TIHK1ATUKE 9UPERCONDUCTORS ON THF. . J.A. Zichy et al., M7-1C, 1987 Boston to be published. POSSIBILITY OF RADIO FREQUENCY CONFINEMENT, Stephen 0. Dean, Fusion Power Anociatea - Recent discoveries of superconducting materials that operate at high temperature may have both tech- nical and economic consequences for magnetic confinement LD-4 fusion. In addition, however, they could also open up the QUENCH DETECTION SCHEME FOR FUSION HAGNET SYSTEMS, S. S. possibility of plasma confinement by radio-frequency fields. Shen and J. R. Killer, Lawrence Livermore National Laboratory The new, high temperature superconductors may impact the feasi- (LLHL) - Although superconducting fusion Magnets wfll be bility of rf confinement in two important wayi: (1) higher designed for stable and reliable operation, it is always temperature superconductors should have higher critical B conceivable that a coll nay quench as a result of certain fields and consequently may allow higher critical electric credible faults. Thus H 1s Imperative that the colls be fields to be sustained in the cavity, thus allowing the protected under such conditions from danage due to over- necessary confining pressure to be achieved; and (2) the higher temperature, over-pressure, and over-voltage. The most commonly temperature superconductor* lower the refrigeration power used schewe of protecting large fusion aagnets Is the Active necessary to maintain the superconducting cavi ty, thus altowing Protection Scheme, which is designed to perform two critical a favorable energy balance. Confinement of fusion plaima by functions: 1) quick detection of the presence of a non- the pressure of radiofrequency fields offers potential advan- recoverfng normal zone, and 2) fast transfer of the colls stored tages, via-a-via other confinement methods, e.g., magnetic or energy Into an external dump resistor. For the high-current- inertia!. These are <1) available steady-state technology, and density magnets being designed for the International (2) possibility of using the same field for heating, confine- Thermonuclear Experimental Reactor (ITER), a reliable system ment and stabilization. Calculations show that recent advancei with very fast response time (less than 1 s) Is required. There in developing higher temperature superconductors may allow the are many quench-detection techniques, both developed and achievement of the very high electric fields required while proposed, for large superconducting magnet systems. Among them, simultaneously reducing the refrigeration power to acceptable the electrical methods are the most advanced and widely used. values. RF power ii available which meet the requirements for Under Ideal conditions very small normal zones could be detected reactor-sixed cavities. Insufficient information currently and monitored with extreme accuracy and speed. However, under exists to realistically assess the effects due to interaction practical circumstances, because of the level of electromagnetic of the rf field vith the plasma sheath. These effects include pickup (n the large Inductive circuits Involved, the sensitivity energy dissipation and plasma stability. This is the most and response time of a detection system are generally much important area for further study. Clarification of the degraded. This paper reviews the state-of-the-art electrical feasibility of a thermonuclear reactor baaed on rf confinement quench-detection technology developed for fusion magnets. It will require an experimental program. presents analysis, test results and comparsion of performance for different techniques and discusses each limitations. Finally, requirements for further development works for LD-3 practical reactor applications such as ITER are outlined. STANDARD-I! AND EXTETIJKC TE3TE DF THE SWISS LO^CIL. *Th1s work was performed under the auspices of the U.S. J.A. Zichy, 3. Jaitot, K. Kvasnitza, C. Efcorctia, G. V?csey, Department of Energy by the Lawrence Livermore National ?aul-Scherrer-Institute (?S:>, 5231* Villiger., Switzerland. M.S. Laboratory under Contract W-7405-Eng-48. 18 LD-5 LD-6 \|i\ \MTI> SI I'KHC'OMU CUM. \MII> \I\C\I 1 l>l COMPARISON OF TWO ICf'S CONDl'CTOKS FOK MHD sICN I OK \ Id 11(1 111! I'OWKK I'l.WI.* !•(; M,,r-i..i. J It Hair. APPLICATION,! J H. Hale. PC Manlon, A M Dwum, Plasms Fusion \ \| 11.,...., Mil 1'!..M.,.. (-UM..II CV11I.T \ inwirl ...in:, Im, I,,-,-,, f'cntrr, MIC Wr linvr rxaiiitnrd two lutmrajr internally roulrd, rablrd Ui^wtl t'.r Aii Vtlih u-cyiiitE «^ .•iiliMamial mill 1, 11: llirral fin all It. 1 rnlr.il drill stri'liBl It \111.1MK conductors wrrr wound two-in-handout" n grooved mandrel in such n way that lliry could be tested alternately. Each sample was instrumented with l!ir iiiiiti.itlf.il.if-Mf tln>ilrsiKli » H in lilt-Hsr..fllrxililrlMliiU Hi Irii-ittn n hratrr at thr renter of the conductor length ('1.9 m for one sample. 4.5 m ... Mi.- priman tit 11! ..f thr It.ttt ...i.laiiniit'iil -tru.linr I lit-1 ..ruin. l..r for the other), and with a pressure transducer and four voltage taps and vlll IK- t,f Ihr calilr m .'.iniluil n|>r will, a i..« t..p|K-r I.. ~ii|M-tt iniiluti.ir one iron-doped ftold/constantaii thermocouple. Ten channels of data wrrr 1 .,11.. t .il.lf ,.!,,l ., ih.ck uallrtl aluminum u.iiiiiul ,l,.-.,ii I tir -li.-alli iv.l! digitized and waved for each 'shot.' Performance teats of ihr conductors -iip|H.rl Ilit-axial l.uuN .in lli<- -atltllt- ami wil: al~t. |.r..vitlt- lli.rm.i! muss were madr nt G, 7 and S tesla background magnetic fields and at heater l..r prttlril ,Bail,M ...frliralilll! ill Hit- r.rlll ..f an rnrrg. .lilinp Plr input energies ranging frou. 60 mJ/Vm3 to 1758 mj/on'. The results of .IIIIIK sit. an.I ili'MKii ,,f llu- maciitt .1 .trm ami :l- pi. .„-, it-.! ..tlv.uil.ici> 111 these tents and their significance for MUD magnet design and economics I...11, |Kif,.mi,,i... ami it..11..tin.> »ill IK- IIIM .ISS,-,I will be discussed. ' Support••«! m p,trt 1» I S 1M)I I'M t Supported in part by US Department of Energy, Pittsburgh Energy iiKlnnmir.ni l)h U '22 MiM '7lf)lJ Technology Center under contrtct I)E-AC'22-8-iPC70512 Session ED Miscellaneous High Tc Superconductor Electronics 7:00-10:00 p.m., Monday, August 22, 1988 SOUID by drilling two 1mm hold clote together in a 3mm thick dttc of ED-1 high quality YBCO. The Mil separating the two holes was reduced by PREPARATION AND PERFORMANCE OF TOROIDAL mechanical erosion until ii wit -• 0.2mm in section. A chancteriuk JBtjCu 0-_ -RF-SQ0IDS, T.Zhang, K.Dlagvl, and triangular dependence of r.f. voltage on applied magnetic flu* *w C.Helden, Tmtitut fuer Angew. Phyiik der Juatuc- observed having flui quantum perkxtkiiy and the expected phaje revenal Lisblg-Onlv. Glassen, D6300 (jlsagsn , F. R.Cenanjr - with increasing r.f. current We deduce £ = J-Uc/»-D - 5 for thli Starting froi dl«k shaped bulk ipsclienfl of ¥Ba_ device. Pre^minary noiie meaiurementt indicaiejhat above SO Hz the flu* noite U approximately flat at 5.10'* ^'Aiz rising lew rapidly than Cu,0? with T near 90 K RF-SQDIDa of toroidal topology with S psraanantly adjuatsd "Bllli-bridge" 1/f at lower frequencies The tank circuit design, magnetic screening and contact w«r« prepared. Contact trlaalng wad done electronic* have yet to be optimised. by reducing it.a cross section eueh that a good SQUID signal was obtained at 77 K. The SQUIDs vere sealed after the adjustment in order to prevent ED-4 degradation by •olsture. Diing conventional 20 MHz read-out electronica the SQUIDs vere operated in High Tc R.F.-ltASEi) SQUID, C Hanaston, O.C. the flux-locked loop eode. Flux noise of the order Sy»ko, U.J. Ysh, and D.J. Zhitng, D*part»»nt of Physics, of 10"** 19 fairly iroall in the microwave SQUID. The preliminary sensitivity at 4.2 K B is 4 • lQ~ tcfy/Wz. Further improvement can probably be achieved by at- ED-6 tenuating the room-temperature noise with a cooled attenuator-circulator JOHETHJCN JJNTTIWi AND DC £ Fin.1 Device structure of mi 1ii»x*torwnvD GBJJ sensor arrays with 9 eloaents fabricated ED-7 on the substrate. Tfce insert nhws (.^lfirgtisent af o t>7»co.l weak link. •liriq •••,•• fjy .-. ,,'.,l!.]f Fig.2 Scheaatic of GBJJ array aountinjc structure ED-8 usod in mi 11 iaetcrutive eYpurisjents. O1ARACTERISTICS OF FLUX TRANSFORMER COUPLED HICH-Tc TrilN FILM DC-SOU IDS. B.H&user and If. Roxalla. Univerolteit Twente - We report on the preparation of high-Tc thin film •icrobridge dc-5QUIDs by lift-ofr and reactive ion etching. As substrates single crystal KgO and SrTiO^ were used, as superconductors either {Y,RE)DaCu0 or BlSrCaCuO. The influence of the width of the alcrobrldges on SQUID-paraaeters Buch as the modulation behaviour, dynamic resistance and the noise figures were studied. Wide bridges give rise to a coaplex •odulation pattern at lower teaperstures, where a aanifold of percolative superconducting paths deteriorate the sinuBodinl •odulation pattern. To demonstrate the coupling to an external field, a superconducting trantforaer was structured in a high- T thin fila on top of the SQUID. The noise level during SQUID-operation including the flux transformer was investi- gated . ED-9 DC SQUID'S FABRICATED UITH YBaCuO 711 IN FlIJtS, Shiguanc WAHC. GuancJi CU1. Yuandong DAI. Huaiing JIAK, Xianghui 7£HG. Jiazhans Fig.3 DC I-V characteristics with and without U. Zhenlei BAO. Shouzhenc WANG, Chuanyi U, Daole YIN, Pokins IJO power, and detected IF output power University, Kai SHAO, Chunhai CAO, Hajin* Solid Devices Research (P >-V characteristic by high Tc Institute, P.R. China. - Ouantua interference effect was observed supercctvluctina GBJJ at 35 GHz with varioua signal power(Pg). in YBaCuO superconductors in aany groups for the Mae being. Due to the difficulties in processing of high Tc superconduc- ting thin filas. the devices were fabricated with bulk Materials with one exception. However the devices aade of bulk aaterials are lack of reoroducibijity and stability, therefore the thin fila devices are invoked in the applications. Ve present our results of dc SQUID's fabricated with YBaCuQ thin filas. The polycrysta)1ine filas were prepared by using electron beaa deposition. After heat treatment, the filas have superconducting transition teaperatures above SO K. The devices were patterned vith vet etching technique in photolithography. The aixture of phosphoric and hydrochloric acids was employed as an etenant. Ve achieved a line resolution better than 5 um and found the degradation of superconductivity can be •iniaized dovn to 2 K. The dc SOUID's consisted of two bridges of 14x26MV and the area enclosed was 46x46 Ma2. Quantua interference effect has been observed in this devices. The enclosed flux inferred froa the periodicity of the "triangle wave" was found to be an order of Magnitude larger than that estiBated froa the geometrical pattern. We attribute this to the so-called "focusing effect" and the penatration of aatnetic field in the bridges areas. No attenua- -75 -70 -65 tion was found in the amplitude up to 15 periods of oscillation. Ps (dB) The noise-fr*quency relation as a function of temperature is under investigation. Heterodyne detection characteristics at 35 CHx. It is clearly seen that ED-10 the detection characteristic is A NOVEL KTS KACNETOHETER. EXPLOITING THE LOW J OF linear for P_'s of leas than about BULK YBCO. J.C.Gallop. S.LI1leyian. C.D.L«ngh«». B.J.Radcfiffe -66dB 20 snmplc- of bulk slntrretl YP(I.,CLI,0 around n magnctisat ion of nOfm. Wi- carri«* intiucmi voltapf ronpont-M in n pick-up coil around the <•onsUifit.-volt.age slops (Slinjiiro stupH) correaponciing to the superconductor, w<* hnve found t hnt L!K? cocpnnvnts at nvun lix-iil u»ci Jlator I'li^jucncy (»n \x- rlimrly seen on the I-V haraonifa of the drive frequency exanlned. The filn sensors wer j alsc fahricjteii. The ED-17 voltagu vb* currcne cfirocccrlsclCK were invusrL^atcil ns the RESPONSE OF HIGH-TC THIN FILM HICROBRIDGES TO MICRO- function of magnetic fluid at liquid nlLrogen temperature. WAVE IRRADIATION, H. RogtlU and B. H»u«er, Univeriiteit The fluK flow was observed In die wide range of magnetic field froa 0.01 to 1 Tesla and the magnetic field could be Twente - We have investigated the influence of •icronave irradiation on the IV-characteriitics of YBaCuO •icrobridfei. volca£t? &t\ the ancle Detween the current and mag tie tic rleld These measurement* were performed at different frequencies in direction was also examined. The condition of the flux flow the gigahertz range as function of the temperature. Special was afU-cted by the direction of external magnetic field resulted in the change of the out-put voltage. On the basis interest was in their behavior at IN^-teaperature. Since the oi thc?Mt? ph€Tio7ie[!\a, three~dloiensional. tluxsensor WAS labllcateu* coherence length or YBaCuO 1* 1 na) is s»tll compared to the The resolving power of the an^le and sensitivity to magnetic bridge dimensions, one would expect a linear dependence of the zero order voltage step on the microwave current, as predicted by the Golovashkin-model. Our results are compared with these ED-14 predictions. MILLIMETEBWAVF. DETECTION BY GBJJ U$JNG HIGH Tc jLTEHLXWDUCTINC ^'BaCuO FI1HS, S.Kila, H.Tanabe, and T• KobayashI , Itepartiiient of Cont-rol Kngineerir*, Taku— ED-18 GRAIN BOUNDARY JOSEPHSON DEVICES BY YBACUO FILMS AND 77K OPERATIONS, T. Yaraashita, A. Kawakami, S. Noge, W. Xu, Technology Magnetron sputtering and screen printing methods 30;m. The annealing of the films at 1000°C Rave abnormal grain prowth. The grain aizc of the films was about 20 to 70iitn. With photolj thography and razor cutting techniques, the films were formed to bridge type Jusephson junctions having a few grain steps and SQUID patterns were observed at 77K. The experiments 21 show that all currents flowing through grain boundaries arc operation principles of device have been diecusMd by Josephson currents in YBaCuO polycrystalline films. Clear Josephson effects were observed in about 30X of the the current controlled resiatlvely shunted Josephaon fabricated devices. The device may have high potentials for Junction model and the two dimentional model of the high frequency detectors and SQUID flux sensors operative at 77K. granule auperoonductor* CIOSTTD is composed of comon bank by the microstrip connect with the high Tc oxide * Supported by the Grant in Aid from the Ministry of Educatioi Sciences and Cultures of Japan. superconductor Mcrobridgea weak links that three di- fferent critical current Ic and (juasipartlcle reals-* ED-19 tance Rn. CIOSTTD made by materials which thin films of high Tc YBCO, LDCO, LSCO, BSCCO et ml. The analog THREE TERMINAL YBaCnO JOSEPHSON DEVICE WITH QUASI- PARTICLE INJECTION GATE, T. Kobtyashi, K. Hishinoto and K. gain can be controlled by the device technique (ion Tooouchi, Faculty of Engineering Science, Osaka University - A new type of the three terminal Josephsoo device HIS fabrica- implantation and particle irradiation and design of ted using the high Tc VBaCuO thin f 1 Ins and the hot quasi - device figure et al.) and by adjusting the external particle injection effect on the Josephson current was closely exaftined. The high Tc filits used here were c-axis oriented shunt resistance Rsxt connected acrosa a particular YBaCuO polycrystal grown on (100) MgO substrates. The thickness macrobridges• of the filn was in the 200 to 500 m range. They were first patterned by the conventional photolithograph and the phosphoric acid etching technique into the constricted grain- boundary Josephson junctions. The junction portions were 10 OB wide and ED-21 100 jm long. Daring the process, the fill surface Missed not WEAK LINK DEVICE FABRICATION IN HrGH TEMPERATURE only the superconductivity but the normal conduction. However, SUPERCONDUCTING THIN FILMS. G. C. Hilton, E. B. Harris, and it rather facilitated the tunneling injector formation by a D. J. Van Harlingen, University of Illinois at Urbana- siaple deposition of the aluainoa electrode onto the junction Champaign. -- We are Investigating techniques for producing portion. All neasurewnts were aade at liauid heliun tempera- ture where the non-equilibrium superconductivity is more likely Josephson weak links in thin films of the high temperature to take place under the Minute injection. Actually, an ceramic superconductors. Films of YBagCusO;.), grown on efficient modulation of the dc Joscphson current was obtained by SrTiCh and ZrO? by dc magnetron sputtering and evaporation the quasi-perticle injection. At present, the current gain from the three metallic sources have been patterned into reached 1.4 . The gate current density as low as 3 A/CM1 was microbridge and proximity-coupled structures. Weak link sufficient to get 90 X modulation. Hnch higher gain is expected behavior 1s Induced by In-situ modification of the coupling to obtain through the structural improvement. It is just by ion milling, material deposition, and surface treatment. underway. Measurements of the critical current, current-voltage characteristics, magnetic field behavior, and fluctuations are made as a function of temperature, weak link dimensions, and interface preparation. We are incorporating the weak links into dc SQUID detectors and studying their signal and noise characteristics. •Supported by NSF(MRL)-DMR86-12860. ED-22 LASER PATTERNING OF YBaCuO AND NbN SUPERCONDUCTING MICROBRIDGES, E. Wiener-Avnear, G. L. Kerber, J. Spar?o, and A. Toth, Hughes Aircraft Coapany - A laser ablation process was developed to pattern thin fil* superconducting devices with 1 sicron resolution. The process was utilized to fabricate sicrobridgea in high Tc (Tc = 90 K) YBaCuO and in NbN (Tc = 15.7 K) superconducting thin files. Controlled Inaer daaage is used to produce regions of weaker superconductivity in the bridges. The fabrication process and the electrical properties of single junction sicrobridges and SOUIDs sade with this technique are discussed. Preliminary results suggest that direct laser writing can be a powerful technique for evaluation or for optimization of representative superconducting devices. Fig.I Device fabrication process, (a) Patterning of the filn by the ED-23 phosphoric acid, 22 Josephson Effect and Macroscopic Quantu* Interference In nnt IC hins field. This alter:; Hip dml jnrtinns S nil IP s iqnn 1 chrti'HCtnrifltic. The abnve-^cnt ion High-Yc Superconducting Thin-Filn Weak Links »t T = 77 K. A. I. Golov»shkin, S. I. Krasnosvobodtsev* L. S. Kuznin, ED-26 K. K. Likharev, Vu. V. Maslennikov, Vu. A. PashkinT CQ GH niG FlLUi: LAUK ABLATION VS. WET ETCHING, P.H. Balkntine. MA E. V. Pechen, 0. V. Snigirev, E. S. Soldatov, *nd Fisher, and AM. Kadin. Dept. or Electrical Engineering, and W.R. Donaldson. Laboratory for Later Energetic*,* University of Rochester - A. N. Tavfcholidio. Narrow lines and mlcrobrldge structures have been etched in sputtered superconducting thin Qlms of V-Ba-Cu-O by variations on two methods. Department of Physice, Hoocow St«te University The first uses standard photolithography followed by wet etching. The second uses a tn««V*M process involving a focused pulsed YAG laser together with a computer-controllable x~y stage to produce local ablation of Lebedev Physic*] Institute , rtcxfea? of Sciences the superconducting Mm. Issues relating to limits of resolution, annealing of film*, and degradation of superconducting properties will be critically discussed for the two methods. En addition. 1-V characteristics of patterned mtcrobridges and other structures will be examined to determine The recent discovery of superconductivity *t teaperatures the suitability of these granular films for possible applications. in exess of 90 K in a class of copper containing oxides has •Research at the LLE supported in part by the Laser Fusion Feasibility Project and by AFOSR contract 84-0318. produced an encriwus burst of research activity In the field. In particular, hopes to create various Josephson junction ED-27 devices have emerged after the first observations of the SINGLE SUPERCONDUCTING THIN FILM DEVICES FOR APPLICATIONS IN HIGH Tc MATERIALS CIRCUITS*, G. K. G. Josephson effect and Macroscopic quantum interference in the Hohenwarter, J, S. Martens, J. B. Beyer, and J. E. Nordman, University of Hisconsfn-Madison - Ue have Investigated several balk high-T superconducting caranics1'2 »nd in thin-fil« different devices based on regions of weak superconductivity c and multiple parallel links in thin films, Hysteretic junctions.1'*'5 symmetric and asymmetric I-V-curves have been observed. Flux flow was indicated. Device switching properties and the dependence of the flux flow signature In the I-V curve on However, the Josephson junction paraneters, in particular applied magnetic field were explored. Both Nb and high Tc thin films were used in circuit fabrication. Contrary to vortex flow their I,J}N products at T = 77 K reported up to now, are not devices based on Josephson junctions those described here do not possess a tunneling barrier and are made of only a single too high. Due to this reason it is of great importance to superconducting layer. Hence they should be applicable to electronic circuits based on high Tc superconducting materials test various methods of fabrication of the simplest Josephson without the need for tunnel junctions. junctions: thin-fil» nicrobridges with the both planar 'Supported by Sandia National Laboratories. dimensions much lurger £, where the Josephson effect is due to weak coupling between neighboring grains. ED-28 GERWUUM THIN FILM GBOWTO ONTO HIGH Tc SUPfflOOMXJCTINC Our first experiments using high-jc filme and direct FILMS. M.Tonouchi, Y.Saka«uchi, K.Hashimoto, Y.Yoshizako, and T.Kobayaahi, Kuculty of Engineering Science, Osaka University photolitography have given very promising results. Josephson — Crystallized Ge thin film growth onto high Tc superconducting films has been demonstrated. Semiconductor / junctions reveal high critical temperatures ( up to 87 K ) superconductor junction foruation is of prime technological improtnnce in view of the high Tc superconducting film and relativel!) high ICRN products ( up to 0.1 *w at application to 3 terminal devices. Ge was chosen as an attractive semiconductor material on accomt of * food lattice T = 77 K ). It means that our simple fabrication technique can matching and fitting of (100)Ge/(00]JYBaCuO. Whether or not the crystallized Ge thin film without intense alloying between yield quite decent Josephson junctions technique operating at Ge and superconductor could be prepared and the epitaxy of the Ge on (OOl)VRaCuO could be possible was a main discussion nitrogen temperatures for such applications as SOUIDs poi nt of the present work. At fi rst, we examined the crystallization of the Ge film on polycrystalline YBaCuO microwave and MM-wave receivers, and other low-scale-integration films. Ge and YBaCuO films were prepared by electron beam deposition and RF magnetron sputtering, respectively. KHEED devices. measurements revealed that the crystallized Ge films were obtained on the polycrystalline YBaCuO substrates above the substrate temperature T_ of 200DC whereas the deposition at the Tg of 100°C resulted in the amorphous Ge growth. ESCA References: study suggested that there was no alloyed layer in the films prepared at 200'C. Then the Ge growth onto the 1001} oriented 1. D. Esteve, J. M. Martinis, C. Urbina et al., Europhys. epitaxial YBaCuO films was carried out. The deposition at Tq of 200B C brought about a spotty KHEED pattern together witS Lett, v.3, No. 11, p. 1337 (1987). faint rings whereas the film prepared at 250"C showed only a ring patterns. Namely, the direct evidence of the possible Ge 2.fl. V . Varlashkin,fl. L. Vasiliev,fl. I. Golovashkin, epitaxy on the YBaCuO films was obtained. At the conference, in addition to the above, we will report the characteristics V. K. Kuzmin et al. Pis'ma v Zh. Efcsp. Teor. n?.[JETP of the Ge/YBaCuO heterestructure and its application to the 3 terminal device. Lett.], V. 46, Suppl., p. 59 (1987). 3. R. H. Koch, C. P. Uabach, S. J. Clark et al., rtppl. Phys. Lett. v. 51, No. 3, p.200 (1967). 4. S. J. Cui, X. F. Neng, S. G. Wang et al., Sol. St. Comm. V. 64, No. 3, p. 321 (1987). 5. H. Tanabe, S. Kita, V. Voshizaka, et al., Jap. J. flppl. Phss. V. 26, No. 12, p. L1961 (1987). Fig.l RHEED patterns fro* the Ge films. The prycrystalline and amorphous Ge films were prepared at T_ of ZOO'C (a) and 100 "c a ED-25 (b), respectively. n^nAMIc SQNIO nprn/WT\r. ^^ 11 •<, 00 5 O O A" A of \ , 7lr '< cevanic VH« z< o Ge ;nrltfts 50 ro 1 in b 1 v rf *- Lhe u rf! n f 1 l qu 1 ( n i t r n - A YBaCuO ' 77 K 4 HI l n AN propnr- 5 10 IS 20 25 Etching Tim* (min.) Fig.2 Sputter-depth profile of the Ge/YBaCuO structure t 1C 23 aatci ial nbout 5 • 1 • 0 Z«« whiili wo* I.n-M'ii fnis a bulk ••anj-ti- uf VlfiairuJIh.Thr 1 V ilmrarlff iil'u :• «i'ii) i«;l;irl> an rol.r i on ! V iiirvps Kfrr olisnveil at 7"K Tli'- »ii M»j;r iiniiut-d :'i(> n! ti'iili ii (hf 1'f) an.1 :n (fif iet »(•(*• . ,.<•, i ilt-n t i.. ihc ^njili- !' ..i: 'si.ni.1 that simriiBf1 thr niinmavp inifmril ->lrp hidlli ij mil aiwa«-. • inn. i IITII I with Josfphnin volliuji1 firqin-in j n-lalinn The phrno»Htw;i mi^hl jf.ull epitaxial YBMCUO fila. The spotty and ring pattern was observed for the fibis prepared at 200 C (a) and 250 C (b), respectively. the bulk 5aiplc of \|Sa'»Tul[i> ED-29 ED-33 FLICKER (1/D NOISE MEASUREMENTS AT THE SUPERCONDUCTING CHARACTERIZATION OF HIGH-TC SUPERCONDUCT- TRANSITION OF THIN FILMS OF YBCO." H. Leoni, Ph. U-rch and J, ING THIN FILMS DEPOSITED ON SILICON AND GALLIUM Clarke, University of California at 3erkeley and Lawrence ARSENIDE SUBSTRATES* D. Chin and T. Van Duier, Electronics Berkeley Laboratory, and P. Rosenthal, R. K. Hammond, and rt. R. Research Laboratory. U. C. Berkeley, 94720 - Fabrication of high-Tc Beasley, Stanford Uni versity — He have measured the low superconducting thin films on widely used silicon and gallium arsenide frequency noise spectrum of thin films or Ygco at the substrates is of great importance 10 microelectronics. It not only provides superconducting transition. The films were co-evaporated or sputtered onto SrTfO^ substrates and patterned into a •advantage of applying matured semiconductor fabrication technology, but 1-ternlnal configuration using an acid etch. The samples were also leads to hybrid devices and circuits utilizing both superconductor and mounted tn a vacuum can and the voltage noise across two semiconductor properties. This investigation aims to grow YBaCuO and terminals was measured as a function of the bia3 current I, ErBaCuO high-Tc thin films on standard Si and GaAs wafers with and applied to the other terminals, and temperature. The spectral 2 without a buffer layer by sputtering from composite targets. The films and density, Sv(f), of the voltage noise scaled with I , implying interface between superconductor and semiconductor ate analyzed by Ruth- erford backscanering spectroscopy, X-ray fluorescence spectroscopy. Auger over the measured frequency range 0.l to 10 Hz. In a polycrystalline sample with Tc • 50 K and a transition width of electron specctoscopy, X-ray photoelectron spectroscopy* energy dispersive to K, the noise normalized to the applied voltage v, Sy1"*2 / V, X-riy spectroroetry. scanning electron spectroscopy, ind sputtered neutral decreased monotonlcally as the temperature was increased frorr. miss spectrometry. YBaCuO films grown on Si wafers with a zirconium- the onset of resistance. At 50 K, approximately the midpoint 2 6 1/2 oxide buffer layer showing TC(R - 0) greater than 60 K have been obtained or the transition, <,J' (1O Hz) / V - 10~ Hz" . In contrast and very little interaction at the interface is observed. In the case of Ylia- to conventional superconductors, the noise at the transition CuO deposited on Si directly, a layer of Cu-Si alloy is present at the inter- did not arise from t Tier ma 1 f 1 uct ua 11 ons» A detailed study of the dependence of the noise on the transition temperature and face. We are working towards reducing the interface interaction. We will microstructure of the films will be reported. report the results for superconducting films deposited on GaAs substrates as well is on Si substrates. • Supported by U.S. DOE under Contract No. DE-fiCO3-76SFO0096, Progetto Flnalizzato Material! e Dlapositlvl per 1 'Elettronica a Stato Solido, the Swiss Science Foundation, and the Office of •Supported by (NSF) ECS-8504631 Naval Research. ED-30 ED-34 HIGH TC THIN FIIW AND DEVICE DEVELOPMENT,* K. Betts, SWITCHING NOISE IN YBaiCn3O,M[CROBRJnc;ES, R.II. H.B. Burbank, A. Cragg, A.A. Fife, P.R, Kubik, S. l*>c, Ono, J.A. Brail, and M.W. Cromar NBS, W. SkocpoU Boston Uuivcnily, J. McCubbin, H. Tran and J. Vrba, CTF Systems Inc.; P.M. M&nkiewtclt and R.E. Howard, ATT Bell Laboraioriea - We lmvt ob- C. Chaklader and G. Roemer, Department of Metallurgy, srrved iiitennitlrnt switching tn Ihc rurrrnt-volta^r rliArnctrrislics (1VC') University of British Columbia; B. Heinrich, Department of of YBnjOujO, microhridgrs. This indicates thai at a given liins point Physics, Simon Fraser University - High Tc thin films of there are multiple metnstnhle voltage states with lifetimes which depend (RE=Y,Eu), have been prepared by . ety of on the bins current and applied magnetic field. The microlmdges nre m&«i« of Ili'm (<500ni«), polycryslalline films irf YBajCiijO, wlncli are magnetron. Sputter target types have included single compos- palternrd by liftoff into structures with sul>-micrometer dtmensiuns. De- ite targets of VBaCu oxide of various compositions and also a tails uf the fabric*!inn process and lite nicaaiiremeulfl will be presented. netal alloy of nominal composition EuBa.Cu . The films were The results will be discussed in the context of fluctuations in the elfertive deposited on substrates which could be held at room or eleva i>d resistance of the hridpe due to motion of trapped flux. temperatures up to - 800 C. Substrate types were Alumina, Sapphire, Silicon* buffered Silicon, YS2, and poXycrystalline SrTiO, and MgO. The effects on the film properties of Applications for high transition temperature superconductors tend lo fncus on the criHral different deposition and annealing condxtions and substrotes will be presented. Critical temperatures Tc(R=»0) to B5 K have currents of wires or thin films. The transition tn Ihc voltnge state is nlao rich in complex been measured and the critical current densities typically and poorly understood physics. We have studied the low voltage behavior nTconstrictions l s follow a (l-TAc) ' temperature dependence. Films developed in tiiin films ufVRai('usOr in an attempt to understand the dynamics of currenl transport by these methods have been processed using wet chemical in a high Tc- material. lithography to form planar superconducting microbridges and RF SQUIDs. The temperature and magnetic field dependence of the bridge and SQUID properties will be presented. The thin films are made using the technique described in Reference 1. Tltc V. Cu, and BaF; are evapnratrd simultaneously onto a room temperature substrate which can be •Research supported by the Canadian Department of National coated with n photoresist mask. The photoresist is lifted off in acetone, leaving the desired Defence (Defence Research Establishment Pacific!. pattern in the as-yet. insulating film. The patterned film is then annealed in flowing oxygen up lo 850C. The oxygen is bubbled through water which reacts with the flotirine, removing it and allowing the proper superconducting phase to form. Details of substrate ED-31 choice, deposition, and annealing will he given. THIN-FILK YBaaCu,0x TUNNELING JUNCTIONS, John Horelandt, R. H. Ono, J. A. Beall, and A. F. Clark*, Electromagnetic Tech- The switching behavior we observed is shown in Fig. t. The sample studied here had two nology Division, National Bureau of Standards, Bouldi-. CO - We bridges (4 fim by 4 inn) connected in piratic! in a simple rtr SIJVH) configuration. The have constructed squeezable electron tunneling (SET) iunctions1 fluctuations were not related to (lie SQUID structure; similar fluctuations were observed with thin-film YBa3Cu30x superconducting electrodes. The films have sharp transitions to zero resistance at 90 K. Ir contrast, in single bridges of the varying dimensions. The smallest single bridge studied was 0.75 the tunneling spectra of the SET junctions taken at 4 K indicate /(in long by .1 //m wide. that the surface of the films has degraded superconducting properties. The derived energy gaps are lower than bulk values The traces in Fig. 11> are lime series of ihr sample voltage nt a fixed currenl Inns and were crushed together to form a point contact. An advantage of with a small magnetic field applied. The corresponding current-voltage characteristic is the SET junction method is that the thin-film sandwich can be shown in Fig. la, with the bias points marked. The dnla shown were taken nt 64 K. The dismantled so that the surfaces of the films can be analyzed, time sfrii-R tlmw a sirikiue !>ntt«rn of switching brUvt-en I wo mf>fa«i:iMi> vnh.ic". A? fb<- possibly reannealed, and tested again. Further results obtained bias current increases, the lifetime in the "down" state decreases. As the magnetic held is after reannealing the films will be presented. increased, llie switching frequency decreases. lUen increases again. t Support provided by the Office of Naval Research. This behavior has important implications f"r low-noise (i.e. SQUID) applications of hiRh- } Presently at the Office of Naval Research in London. T( thin films. We will present results of our investigation of the impart of different growth onndilions on the presence ami magnitude of the switching events in YB.^CujO, films. 1) John Moreland and P. K. Hansma, Rev. Scl. Instrura. $5., 399 The lifetimes and field and temperature dependences will be discussed using a model of pinning and un-pinning n single vortex in the bridge region. ED-32 INTERACTION AMONG SUPERfONTlUCTINn WEAK LINKS IK \ BULK S.WLF OF YBaCuO AT 77K, Y«ng Tio.l.iu Dong,Sun ZiQiang, and Chen XinHang, References. Department of Physics, Northwest Hnivrrsilv. Xian.Chinn- The Josephson efferi was dirprtly obscrvpd wiIh a piece of superconHmiiny 1. P. M. Mankiewich ri 24 National Laboratory, Argonno. IL 60439. A film of YB.-^CuO a few pm thick deposited on a MgO substrate, was spring loodi'a to close proximity of a LINbO piezoelectric substrate with 19 MHz interdigical transducers/ which could be used to gc-ner- ate surface acoustic waves at several hormonxcsf up to ?jU fili^. This same set of transducers could bo used to generate and detect RF eleotroraagnetLc (o-m) pulses up to 2 GHz. We report here an investigation of the RF e-m attenuation (brunkthrough signal from A5O Hits to 2 CH=) as a function of temperature. A non-interfering simultaneous four-wire resistance measurement was sometimes performed to assess and locata the Kuperconduc- ting transition, at T <* 85 K. An increase in the RF e-tn attenuation was observetf as the temperature was decreased, with -t 1* a change in slope at T . An unexpected and repeatable Jump in rh° RF o*d attenuation was also obscrved at 1 ow temperature (-25 K) . Tlie background RF signal due to the substrate was range. Research partially supported by AFOSR Grant Mo. AFOSR 84-0350. Figure 1. a. J-V chwncterisiic of a mirrobridge. b. Volt age-time scries of switching ED-38 events al various bias points. MICROWAVE CAVITY RESONATOR HADE FHOM YBsCuO, W.J.Radcliffe. J.C.Gallop. C.D.Langha«. H.Gee and H.Stewart. National Physical Laboratory, Teddlngton. UK - We have constructed a cylindrical •icrowave cavity, length 36a» and radius 12. 5am, and wall thickness Ifnui froi bulk sintered ED-35 saaples of YBa-Cu^O^. the three component pieces being held ULTRA BROAD BAND MEASUREMENTS ON HIGH TV CERAMIC together by a clip*. The temperature variation of real and SUPERCONDUCTING TRAfiSMlSSION LINES, K.Araki, I. Iwasa. imaginary components of the surface resistance have been Y.Kobayashi, T.Naritd* and H. Mori sue, Saiiama University, •easured, fr-r five different resonant frequencies f In the *Kawatettiu Mini ny Co, — By usiny a network analyzer, we hatre range 10-1 f^HHz fron 4.2K to 300K. Comparison of the results measured over frequencies from JOHHz to 26."JGHZ the transmission for surface resistance with the predictions of Hattis-Bardeen cinu ri*I It^L L jon cndra^tori^Lic^> ol superconducting? transmission theory shows the expected dependence on f , but we observe a lines at 77K which are composed of lym Lhick high Tc ceramics quadratic dependence on T, rather than the exponential (YBajCiuO?) on YSZ substrate with U.6mn thickness. Since all the behaviour of that theory. Analysis of the surface of the measured data m Lhe Irequency domain are stored in memory, time material has been carried out and possible methods for domain responses, o.«. pulse delay, wnvetur arc drawn u> electron lieam lithography system. Minimum line ED-39 TUNNEL SPECTROSCOPY IN Nb/BiSCCO POINT CONTACT JUNC- character 1stics ot the lransmission lines due to the TIONS, A. Barone, A. Di Chiara, G. Peluso, U. Scotti di Occio, superconduL t ini; mnleruils and the line structure, separately. Dipartimento di Scienze Fisiche, universita di Napoli, Piazza- le V. Tecchio, B0125 Napoli, Italy, and INFN, Pad. 16 Mostra ED-36 d'Oltremare, Napoli, Italy - Superconductive electron tunnel- ing spectroscopy is one of the most powerful technique of in- A FILM TRANSMISSION LINE RESONATOR TO MEASURE THE MICROWAVE SURFACE RESISTANCE OF YBagCu^.x, M.S. Martens, vestigation of important properties of superconducting mate- D.P. McGinnis, G. Hohenwarter and J.8. Beyer, University of rials. Moreover it gives specific information on the nature Wisconsin-Madison; D. S. Ginley, Sandia National laboratories— of the surface of the sample, as the presence of non supercon- Me have constructed microstrip transmission line resonators ductive and/or non conducting layers, the granular structure with YBagCu^Ofi.g ground plane, StO dielectric and Nb top of the material, etc. In this context the point contact con- conductor. The fiIm resonator is a low impedance section figuration has been widely employed with ceramic compounds. nx/2 long and the wave is launched from a coax line. Tight coupling is provided by the discontinuity between the 50 n feed Indeed, in spite of the intrinsic mechanical instability ines and the .05 fi resonator section. After de-embedding the point contact Junctions seem to provide a more direct physi- transmittance data of the structure, the surface resistance of cal insight over planar configurations such as bulk or thin the ceramic superconductor can be computed. The surface film junctions. This is probably due to the complex structure resistance of YBagCusOg.g at 4,2 K was about a factor of 40 of the surface. In this communication we report the prepara- higher than that of theoretical Nb at 4.2K over the range 2.9 - 6 GHz. The power law behavior versus frequency of the surface tion technique and preliminary characterization of BiSCCO resistance is roughly quadratic as is consistent with two-fluid pellets. Results concerning the energy gap A and 2i(o) KTc of analysis. the BISCCO samples obtained by Nb/BiSCCO point contact junc- tions will be presented. Measurements on different pellets Supported in part by Sandia national Laboratories. at different temperatures and contact pressures have been performed giving rather reproducible and consistent results. The differential resistance measurements performed by a stan- ED-37 dard modulation technique show quite evident and sinoetric RF ELECTROMAGNETIC INVESTIGATION OF AN YBi Cu 0 THIN structures which can be related to the energy gap of BiSCCO. FILM BY PROXIMITY COUPLING. H.-P. Baum. A. Schenstroin. V. Further work also employing different structures is in pro- Zheng. fl.K. Sarnta and M Levy. University of Ulsconsln- gress. MiIwaukce, Hilvaukee, VI 53201; R.T. Kampwlrth. Argonne 25 Session P-2 Plenary II SMES 8:15-9:30 a.m., Tuesday, August 23, 1988 potential impact of the high Tc materials teased o n perlor P-2 will be included. SUPERCONDUCTING MAGNETIC ENERGY STORAGE." W. Hasscnzahl. Lawrence Berkeley Laboratory • A Superconducting Magnetic Energy Storage (SMES) model is being designed for use by botb the Strategic Defense Initiative (SDI) and the electric utilities. The historical development of SMES will be described followed by a discussion of the status of the current program, which is now funded by both SDI and the Electric Power Research •This work was supported by the Director. Office of Energy Research, Office of High Energy Institute (EPRI)- The economics leading 10 the choice of this type of energy storage for the and Nuclear Physics. High Energy Physics Division. U.S. Dept. of Energy, under Contract application and (he ultimate potential of SMES for utility applications will be diacused The No. DE-AC03-76SP00098. Session EE Noise in SQUIDs 9:45 a.m.-noon, Tuesday, August 23, 1988 EE-1 environment may be degraded from .hat found in laboratory and sheets have been conducted to identify contributions to HOT ELECTROH EFFECT IN THE dc SQUID.* F. C. such noise. Results have been obtained for bulk and Lhxn- WELLSTOOD, C. URBINA", and J. CLARKE. University of film samples utilizing both the conventional low-temperature California at Berkeley, and Lawrence Berkeley Laboratory - mat" ials as well a3 the new hibh-tesperature oxide He have Investigated the tenperature dependence of the oaterials. Experiments have been conducted to quantify flux sensitivity of thin-film de SQUIDs down to 20 mK. The unite redistribution and flux motion in superconductive sanples nolae In our early SQUIDs did not decrease Delow about 150 subjected to temperature changes, tenperature gradients ana mK. We attributed this to a hot electron heating effect In magnetic field gradients. These investigations have been the thin-filo AuCu resistors shunting the SQUID. conducted at magnetic fields typical of cany SQUID Tneoretlcal investigations of the effect show that the applications with field Intensities auch smaller than temperature or the electrons In the shunts, T , should obey 1 1 e critical values. Penetration-depth effectSi flux-pinning Te - (P/nr) ' , where p is the power dissipated In the effects and flux-motion effects have been observed. The shunts, ft Is the volume of the shunts, and Z Is a various types of experiments conducted alonfc with specific proportionality constant. Experimentally we found I • 6 » results will be described. 10* W/n'K* for our system. He have redesigned the shunts, by adding large thin-film cooling fins, so as to increase their volume substantially. This technique has reduced the effective electron temperature in the shunts to about uo mK. EE-5 with a corresponding Improvement in the sensitivity of the Seven-Channel rf-SQUID with 1/f Noises Only at Very Low SQUIDs. The lowest observed value of S$/2L is 5 ± 0.6 H In a Frequencies, H.OHTA , I.TakahiUt. Y.Takahashi*. K.Shinadat. Y. SQU5D with Inductance L • 0.51 nH (St Is the spectral YaMdat, T.Hanasakftt, Y.Uchikawa' and M.KoUnt .The Institute density of the flux noise). Recent work on devices with of Physical and Cheficat Research, Shiaadzu Corporation* and thick Oun) cooling fins will also be presented. Tokyo Denki University* --A seven-channel rf-SQUID uxnetoMter has been Mde of Quasi-Planar Josephson Junctions for oto- 'Supported by U.S. DOE under Contract No. DE-ACO3-76SFOOO9S •agnetic Beasureaents. It has a sensitivity of 20fT//H2 and has ••Centre d'Etudes Nuelealres De saclay, France. detected alpha-waves fro* huaan brains and neuroaagnetic fields evoked by optical stimulation of the eye.lt has been experimen- tally confirmed that the SQUID ugnetoMter has 1/f noises only at lower frequency than O.OOSHz- To our knowledge,lost SQUID s EE-2 have 1/f noises at lower frequencies than several hertz.Recently Koch at PTB has Mde a SQUID with 1/f noise at lower frequencies NOISE IN D.C. SQUIDS WITH Nb-Al3Oi-Nb JOSEPHSON than one hertz using his Self-Aligned In-Line junction which has JUNCTIONS, M.W. Cromar, J.A. Deall, Diane CJo, K.A. Mamie, R.H. a very saal I junction-area of 0.2 MUX I fim. Our Quasi-Planar junction his the weak link portion which is ude by electron- Ono National Bureau of Standards, H. Simon TRW - The sensitivity uf beam lithography and dry etching to be 200 ra wide and 13 m D.C- SQUIUs at low frequencies is often limited by noise resulting from thick and therefore its junction area is 200raiX13na.This SMII- fluctuations in the critical current of the Josepljaon junctions. The perfor- ness of the Junetin area of Quasi-Planar junctions could be the mance of integrated circuit SQUIDs incorporating high quality Nb-AI-Oj- reason why their SQUID's have such a low-frequency 1/f noises. The QP junctions have the 7 m long weak link which is shorter Nb tunnel junctions, which are expected to produce less noise from critical than the coherent length of niobtua at 4.2K. The temperature current fluctuations, is described. The junctions are stable and have sharp dependence of the critical current of QP junctions before anod- gap structure and low stibgap cundurtanre. Juiiclitnis wild a critical cur- tzation of the weak link portion is consistent with that of a rent density of 1000 A/cm1 liave a V of 30 mV. The SQUIDs arc well clean-)i»it short weak link. After electrolytical anodization of m the weak link portion reduces the critical current fro* 30wA to damped, lie "- 0. J, and have modulation parameters, (1i, of approximately 2/iA for use of rf-SQUID s> the temperature dependence of the 1- SQUIUs with inductances of approximately 100 pH have smooth volt- critical current of QP junctions becomes the sue as that of a age vs. flux characteristics while those with indurtaurrs of npproximatrly tunnel Josephson junction. This observed transition of a QP 5 pH have resonances which cause very sharp characteristics. The low- junction from a short weak link to a tunnel Josephson junction is consistent with the general theory of D.8.Arnold's. Before frequency excess noise for these SQUIDs will he reported. anodizatton of the veak link portion ,QP junctions irradiated by microwave radiation shows subnarmonic energy gap structures on the current-voltage curves which is also consistent with the results of the second paper by D.B.Arnold about subgap harmonic EE-3 structure of Josephson junctions. LOW FREQUENCY NOISE IN FLUX-LOCKED DC SQUIDS,* Y. Miki" and B. Muhtfeldcr, Stanford Univ., j. Lockhin. San Francisco State Univ. and Stanford Univ., C. Tcjchc, IBM York town Height*, and EE-6 M Cromtr, National Bureau or Standards, Boulder - We hive measured the noise of flux-locked DC SQUIDs at frequencies between 100 Hz and 10-4 Hz. Devices fabricated at the IBM Research Division and at the LOW NOISE SWITCHING OF A SUPERCONDUCTING National Bureau of Standards, Boulder, were studied. Measurements were CIRCUIT BY A LASER INDUCED WEAK LINK,* Charles E. Cunningham, made in DC magnetic fields of 10-3 G using conventional shielding and Bias Cabrera, Stanford University - We have designed a scheme for reducing also in an ultra-low magnetic field environment of 10*7 G using the noise in low frequency SQUID measurements made below the 1/f knee in expanded superconducting foil shields. Slow feedback-controlled cooling the noise spectrum by inductively modulating the input coil at a frequency above of the SQUIDs was employed in an attempt to minimize trapped flux. the 1/f knee. We use superconducting switches made from 200 A thick Nb The DC SQUID devices, the electronics which allow flux locking, and the sputtered onto a sapphire subs one, where we illuminate the Htm through a Fiber probes and magnetic shields will be discussed. optic with a laser diode. The photons break Cooper pairs directly, since the film is thinner than the superconductor's coherence length and is only a few 'Supported by the NASA GP-B Program at Stanford University and by optical penetration depths thick. The order parameter and critical current are NSF Grant DMR84-15172 at San Francisco Stite University. depressed to zero through nonequilibrium dynamics with the film remaining below its thcrmodynamic transition temperature. Thus, in principle, the "Permanent address: Quantum Metrology Dept., National Research switching rates are limited by the quasiparncle recombination rime, rather than Laboratory of Mc.rology. Tsukuba, Japan. by the slower time of phonon escape from the film. We shall report our test measurements of a single laser switch. EE-4 INVESTIGATION OF HOISE SOURCES IN SQUID ELECTRONICS, T.R. Clea, M.J. Goldstein, and J.W. Purpura, Uaval Coastal Systems Center; J.H. Claassen, S.A. Wolf, L.H. Allen, and D.U. Cubser, Naval Research Laboratory - The perTorcance of * Supported in pan bv the Office of Naval Research. Contract Number SQUID-based electronics outside a laboratory-controlled NO0O14-87-K-Ol'35. 26 Laboratory, Mitsubishi Electric Corporation -- We report a EE-7 SQUID amplifier with a novel tuning circuit that can be easily coupled to a finite-iopedance source such as a superconductor- RELIABLE LOW NOISE DC-SQUID,' P. Carelli, L'Aquila Ir.sulator-superconductor (SIS) mixer. The input circuit of the University, Italy V. Foglietti, M. Pullanoand R. Leoni, 1ESS-CNR, 00156, SQUID aaplifier la a T network teroinatad by an input coil f and Roma, Italy - A completely new designed multiloop dc-SQUID has been can be tuned at its resonance frequency. The nerit of using the input circuit is that the SQUID amplifier can bo optimized fabricated. The device is made of six different layers deposited on a, 5.08 without changing the SQUID-Bpecifie parameters by adopting cm silicon wafer The layers are patterned by means of optical lithogra- proper T-network parameters. Furthermore a large dynamic range phy. The chromium masks used were made using our facility of Electron of the amplifier is obtained without decreasing gain by using the SQUID with snail mutual inductance between the input coil Beam Microfabricator. Every chip is 6.25 mm square (out of 24 of the and the SQUID loop. The design of the SQUID amplifier Is based same wafer) contains two SQUIDs and their input coils. The tipical on Q source impedance of 50 oho and a signal frequency of near coil inductance is about 1 fiH. The junctions are planar windows 2 /im 150 MHz. A planar thin-fila dc-SQUID with a 10-turn spiral input square on SiO made of Nb — A'A0» - PbAuln with a current density of coil and a damping resistor in parallel with SQUID loop 3 inductance is usod in experiments. The performance of the SQUID 500 A/em and a Vm > 20 mV. The oxide barrier was grown following amplifier is measured at i.,2 K. The measured gain and noise the recently improved Grejner technique developed at the IBM laborato- temperature of the SQUID aaplifior are 23 dB and 1.8 K, ries. The device was repeatedly cooled and stored in air for four months. respectively. The saturation level as high as 100 K nt the input of the aaplifier is achieved. After this thermal cycling we observed no variations in critical current. The measured mutual inductance between the input coil and the SQUID is 2.1 nH, the SQUID inductance is about 28 pli. The energy sensitiv- ity referred to the input and in flux locked loop is approximately 700h, in the white noise region with a 1/f corner frequency at 10 Hz. These EE-9 SQUIDs are already operating in the gravitational wave experiment of MEASURED PERFORMANCE PARAMETERS OF CRAOIOHETERS WITH DIGITAL OUTPUT, H. Jutrx, 0. Orung. E. Crocoll, R. Kcrwig. and Rome Group in Geneva, and in the four channel system for biomagnetic M. Nfun«us, Umvtriitit Karlsruht - Fint order gradiomattri measurements operating in our laboratory. ana dc SOUIO comparators tiava bttn int»flr»t«d on the sam* chip in tht Nb-Nb O.-PblnAu tachnology and optratcd in • flux-lock«d 'Supported in part by Progetto Finalizzato Material! e Dispositivi per met»r output, * vary low flux noist of T IO~? *n//Hl >nd * I'Elcttronica a Stato Solido of C.N.R. Italy. EE-8 A DC-SQUID AMPLIFIER WITH A NOVEL TUNING CIRCUIT, T. Takani, T. NogucM, and K. Ha lanaka, Central Research Session MF NbN and Nb3AI 9:45 a.m.-noon, Tuesday, August 23, 1988 700"C, was carried out to Improve the superconducting properties MF-1 of the Nb/Al-Hg wire; T , B , and JA*.2 K, 18.5 T) were increased to 16.2 K, 2276 T and 1 x 10 A/an , respectively, EXPERIMENTAL STUDY OF FLUX PINNING IN NbN FILMS uhich are comparable to those of the commercial Nb.Sn MF AND MULTILAYERS: ULTIMATE LIMITS ON CRITICAL CURRENTS IN conductors. High-field superconducting properties were measured SUPERCONDUCTORS,* K.E. Gray. R.T. Kampwirth, D.W. Ciponc II and by the hybrid-magnets at Tehoku University. J.M. Murduck, Argonne National Laboratory • We have used measurements of the critical temperature, Tc, critical magnetic field, BC2, and critical current density, Jc, in samples with a well-defined pinning geometry to test a new model An early study of Nb.Al formation by a diffusion reaction between bulk of flux pinning which allows us to predict the maximum potential depinning Jc in Nb and Al indicated no A15 phase for/nation at reaction tenperatures below any arbitrary superconductor. The influences of the various parameters arc 1000*C. Later, it has been demonstrated chat.reactions between very thin separated using a Kramer-like analysis near BC2. The effectiveness of planar Nb and Al layers(vapor deposition. Jelly roll ), or Mixed fine powders, surface and grain boundary pinning structures in films and multilayers of NbN is let the A15 phase fora even at reaction temperatures around 850"C, and found to be about 15% of the maximum, which occurs for an ideal planar that they yield the high critical current density J and the high critical vacuum interface. The dramatic increases in Jc of the multilayers of NbN over temperature Tc of 15-16 K. This T£ value is still higher than the value of single NbN films, measured at 4.2 K and 20 T parallel Held, are found to be a 12 K measured for the arc^ntelted samples annealed at the same temperature result of both increased BC2 and increased pinning due to the alternating barrier ranges for a long period. However, it is not so easy to attain such a layers of insulating A1N. The strong pinning forces, exhibited by both pinning short-distance diffusion in a large-scale conductor because of the poor cold structures, were significantly reduced for defect spacings smaller than the flux workability of the Nb/AI composite. Furthermore, the above mentioned core diameter, however, in an optimized multilayer the pinning force reached iet hods ;ntary -22% of the theoretical maximum. A large anisotropy, similar to thai observed :ly, we succeeded to overcome this problem by using the Al-Hg in high-temperature superconductors, is found in the critical properties of the alloy cores instead of the pure aluminum cores for the continuous, NbN multilayers, and an anisotropic model is developed. This model predicts a multlfilamentary Nb/AI composite; the addition of Hg to Al-core diminishes maximum potential J value of at least 2x108 A/cm2 in YBa2Cu3O7at low c 7 2 the defference In hardness between the pure Nb matrix and Al-core and then reduced temperature and 20 T field. This would be reduced to~4xI0 A/cm if improves the workability of composite, resulting Into a success In , a pinning strength no larger than the highest effectiveness found in NbN could fabricating a wire with ultra-fine Al-core fllanents(about 0.1 urn dian.). be realized in YBa;>Cu3O7. In this study, it is shown that additive elements Ag, Cu and Zn in addition to Hg are also effective In fabricating the continuous ultra-fine Nb.Al This work was supported by the U.S. Department of Energy, Basic Energy multifLlamentdry conductor. Moreover, superconducting propertles have been Sciences-Materials Sciences, under contract #W-31- 1O9-ENG-38. in detail investigated In relation to the effects of the additive elements. Table 1 shows the Al-based alloys investigated in this study and the workability when they were used in the composite as the core materials. MF-2 For the Al-based alloy, (1) no second phase which can be observed by the EFFECTS OF ADDITIVE ELEMENTS ON CONTINUOUS ULTRA-FINE optical microscope, (2) the hardness comparable to the Nb matrix, are Nb Al MF SUPERCONDUCTOR, T. Takeuchl, Y. rijinia, M. Yuyama, required to get the good workability of composite. To Increase the M. Kosuge and K. Inoue, National Research Institute for Metals, hardness, Al-3atZAg, Al-1.latlMg-0.7atSSi and Al-2atZCu were hardened by aging at a temperature of 150rC, 160C and room temperature, respectively. superconducting properties could Be fabricated by the composite- Ce and Si can be added to Al-cores by using the ternary alloys so as to process using various Al-based alloy cores and pure Nb matrix. avoid not only decreasing the hardness and but also precipitating any Additive elements Hg, Ag, Cu and Zn, which are the principal visible second phase. The best workability of composite was achived by solutes involved In the precipitation hardening, harden the lOatZMg, 2atXCu or latZCu-latZGe addition. These Al-based alloy rods of 6.9 Al—core preferably and then improve trie wortcab1111 y oi No/Al mm^ were inserted into a niobium pipe of 7mm ID and 14 ram 0D, and resulting tnul ti Ei lanentary composites• This permits the composites to be single-core Nb/AI composites were cold-drawn Into a wire of 1.14 nm^ and cut cold—drawn Into wires with ultra—fine Al—based alloy fi 1 atnents into short pieces. The 12! short single-core wires were packed into a (number of filaments : 1.7 x 10 , diameter :-0.1 urn). The best niobium pipe of 14 mm ID and 20 ran 0D, and resulting 121-core Nb/AI workability was achieved by lOatSMg or 2at*Cu addition, where composites were cold-drawn into a wire of 1.14 tmp and cut into short the vlckers hardness was comparable to that of Nb matrix. Simul- pieces, again. This procedure was repeated two times more and, finally, 1.7 taneous addition of Cu and Ge to the Al-core was also studied. x 10 (121 x 121 x 121)-core Nb/AI composites with continuous ultra-fine Resulting short diffusion distance between Nb matrix and Al- Al-based alloy core of *.0.1 urn dlam.,were fabricated. Fig. 1 shows the cross-sectional view of the 1.7 x 10 -core Nb/Al-5atXMg composite. The composites were reacted at 7OO-95O'C to form the Nb,Al filaments by the ture to form Nb.Al with high Tp. With decreasing the diameter diffusion reaction between the Nb matrix and the Al-based alloy cores, and of Al-core, T increased at first, reached a maximum around 70 then their .1 and T were measured by the four-probe resistive method. nm dlaai., andShen decreased. Maximum T values of Nb/AI-3aiX Ag. Nb/Al-">at£ Mg, Kb/AI-latZCu-1 atfcGe, &b/Al-2atZCu and Nb/Al- SatXZn multifilamentary wires reacted at 750*C were 15.6, 15.5, Fig. 2 shows the dependent 15.1, 14-9 and U.5 K, respectively. J (4.2 K, 10 T) of 1.5 x various Nb/AI multIfilatnentary i mductor reacted at 75O'C. With decreasing 10 A/cm and B 7(4.2 K) of 21.8 T were obtained for the the Al —core dlam., T increases at first, reaches a maximum around 70 nm Nb/Al-Mg wire. CThe two-stage reaction, consisting of a first diam., and then decreases. Maximum T values of ND/Al-3atJAg, Nb/Al-5atJHg, reaction around 9?0 C and & subsequent second reaction around Nb/Al-latXCu-lal2Ge, Nb/Al-2at*Cu and Nb/Al-5at*Zn multifIlamentary 27 conductors reacted at 75O'C are 15.6, 15.5, 15.1, 14.9 and 14.5 K, respectively. The Al-core diam. at which T reaches a maximum is increased 4 2 K J by increasing the reaction period. However, the optimized Tc at a given Al-core diara. is also depressed when the Al-core diatn. Is decreased too •uch. The IS,(4.2 K> estimated by the extrapolation of Kramer plot and the J (4.2 K, 1-T2.5 T) were also found to vary with the Al-core dian. as well as the Tc. However, in comparison with the case of Tc, the Al-core di-ro. at which J reaches a suixltDuin was shi fted to sical ler one. This tendency was enhanced by reducing the magnetic fields. With increasing reaction temperatures, the T and J (4.2 K) optimized at a given temperature, were increased and then saturated above 800eC, while the optinized B , continued co increase gradually at least up to 950"C Pig. 3 shows typical results of J measurement in magnetic fields up to 21 T at 4.2 K. tn the sequence Ag-*-M|-«-Cu-Ge -*-Cu -«-Zn, good high-field W-5MJ B00°C-3 r, properties are obtained, reflecting the order of T values. The highest J flU-3Ag 600°C-3 h at 10 T of 1.5 x 10 A/cm' was obtained by the single-stage reaction at 956 ONI^AJB2OJ B5D*C*05^ •C for the Kb/Al-5atXMg wire. The highest B _ of 21.8 T was also obtained 7Nh/W-5Zn 850^- 1 h for Nb/Al-lOatJMg wire. As shown in Fig. 3,the two-stage reaction which consists of a first reaction around 950 t and a subsequent second reaction IMVAl-lCu-lCt BOTC-OSh around 700*C.improves the high-field performance of the Hb/Al-Mg conposlte; J of 1 x 10 A/cm is achieved at 18.5 T. T and B ,(4.2 K) were also improved by the tvo-stage reaction to 16.2 K and 22.§ T, respectively, although the two-stage reaction conditions have not been optimized yet. These excellent high-field superconducting properties comparable to those of the commercial Nb,Sn mul tifilamentary conductors. Indicate that the Nb-,A1 Fig. 3 Typical J - B . jrves of con i ultra-fine Nb.AI nultlfilanentary conductor is very promising for practical use. multifilamentar conductors i 'arious Al-basea alloy cores. References MF-3 (1) J.C.Kohr, T.W.Eagar and R.M.Rose, Hetall. Trans., jl, 1177(1972). (2) J.R.Cavaler, A.I .Braginski and J.Greggi, J. Appl. Phys., J51_, 659(1987). LOCAL PINNING-FORCE DISTRIBUTION IN NbN FILMS. (3) S.Ceresara, M.V.Hicci. N.Sacchetti and G.Sacerdoti. IEEE Trans, on A. PruyinbooniandP.il. h'es, KamcrlinghOnncs Laboratory, Slate Magnetics, HAG-11, 263(1975). University Leiden, The Netherlands -We have performed measurements of the flux-flow resistivity on a thin film of (4> C.L.H.Thieme, S.Pourrahini, B.B.Schwartz and S.foner, IEEE Trans, on NbN. By fitting the resistivity, measured as a function of the Magnetics, MAG-21. 756(1985). current, to a theoretical expression, we were able to obtain (5) J.L.Jorda, R.Flukiger, A.Junod and J.Huller, IEEE Trans, on Magnetics, the distribution function of local drpinning forces in the MAG-17, 557(1981). film. It appears that the distribution is very broad and that (6) K.Inoue, Y.Iijima and T.Takeuchl, to be published in Appl. Phys. Lett.. only a minor fraction of flux lines is moving at what is usually defined as Jc. These observations are in agreement with the results of the pinning force measurements. Thrse Table 1 Workability of Nb/Al composite using various Al-based alloy cores. measurements reveal that, at high fields, pinning is limited by flux-line shear and that the effective channel width for shear Composition of is equal to the flux-line spacing. They suggest that variations Al alloy(atX) (observed by OH) R - 0 R - 160 Nb/Al composite of the local depinning force on various length scales, always (Kb) - SO 130 - allow the flow of single rows of flux lines. (pure Al) _ 25 34 - 5Hg no 80 138 good lOHg no 102 180 very good 5Zn no 74 84 not too bad MF-4 3Ag no 65(80') 80 not too bad THE EFFECTS OF HIGH-FLUENCE NEUTRON IRRADIATION lCu no 58 - - ON THE SUPERCONDUCTING PROPERTIES OF MAGNETRON 2Cu no DKUO**) 135 very good SPUTTERED NbN FILMS.* H.W. Weber and P. Gregshammer , 5Ce significantly 42 94 bad Atominstitut der dsierreichischen Univcrsitttcn, K.E. Gray and R.T. 3Ga significantly^ 67 - very bad 4Hg-4Ge significantly 50 60 bad 0.8Mg-0.4Ge significantly 39 _ 0.8Mg-0.4SI no 65(81") - - field magnets, especially for fusion applications. We report neutron irradiation 1.1HR-0.7S1 no 78(98") 125 not too bad experiments on sputtered NbN films, up to a fluence of 1fj23 nv2 (E > 0.1 1.3CU-1.OSi significantly 101 - _ MeV), which prove that NbN films are also extremely radiation-hard, high-field 1.3Cu-1.0Ge slightly 91 - - superconductors. Both the transition temperatures, Tc, and the normal stale ].0Cu-1.0Ge no 80(75') 117 very good resistivities show only slight changes with neutron fluence. While the critical R:reducdcion ration, ': aging treatment at 150*C, current densities, Jc, degrade by as much as 30% in an intermediate field range ": aging treatment at 160 °C, *: aging treatment at room temperature. (6-14 T), the high-field data (near 20 T) show virtually no change of Jc due to either the radiation-induced increase of Bcj or the occurrence of peak effects near the upper critical field. •This work is supported in pan by the Bundesministerium filr Wissenschaft und Forschung, Wien, and the U.S. Department of Energy. Basic Energy Sciences- Materials Sciences, under contract #W-31-109-ENG-38. MF-5 EWXESS CCtTOCL PCR WE IOW TBCERUUIE EEP0SITICN OF NIOBUK-MTMIE TOD) Flue, * A. C And«r>cn, D. J. Licfctanalnsr an! w. T. Brogan, Lincoln laboratory, m«»i.l»mn» Institute of Technology - NiobiiM nitride, of the xgatoenducton for «hidi a Junction technology li available. Is the only one that can be operated in the 10 X a«bi«nt provide! by reliable cryogenic rtfrigeratorc. araequently, eony cryogenic electronic devices and circuit* currently being developed nee >Uf. However, the reactive sputtering [• i n eel widely uead for the deposition of *« filMe i» etill poorly mderetood and the ieeuae of the Fig. 1 Cross-sectional view of the 1.7 x 10 -core Nb/Al-5at%Hg composite 1 control for the deposition of these filas only recently wire of 0.7 nnf diam.. began to be addreseed. VM have investigated the pur— of dc and if sagnetron reactive sputtering of Itfl with the purpose of clarifying the issues uhich are ixportant far imii ees control. Based on a sixple physical Model of the deposition jjrrraes, a series of parameters (plasma *T™^n^», plaeea concentration of reactive species) have been selected for Etufy and their effects on the properties of the filxs (transition tsaperature, roae tewpera- ture resistance, rf surface iBpadance) have been evaluated experimentally. Based on these experiments, a sisple feedback scheme using the plasm inexvtamy as a control parameter uos implemented allowing for the consistent deposition of high-quality films, ine same scheme can be used for the control of the stoichiometry of any reactive sputtering process, including the deposition of the new high-Tc oxide films. Heat Treatment 750*C 10 100 1000 Al-Cort 0l»meter(nm) Fig. 2 Dependence of T on the Al-core diameter for various Nb/Al Ihis work is supported by the Departments of the Air Force and multifilamentary conductors reacted at 750'C. Navy. 28 MF-6 MF-7 REACTION KINETICS OF A1S FORMATIOI N IH Kb-Al POWDER FABRICATION OF HULTIFILAMENTARY Nb3(Al,Ge) WIRES THROUGH A MODIFIED JELLY ROLL PROCESS, K. Tachikawa, Faculty of METALLURGJRGYY HIRE*. H~RK- R. Coffey aanmd D. A. Rudnan, Department Engr., Tokai University, Y.K.intsada and E.Suzuki, Showa Electric of Material! Science and Engineering, C. L. H. Thieme *nd S. Wire and Cable Co.- Nb/Al-Ge alloy composites were fabricated Foner , Francis Bitter National Haguet Laboratory**, H.I.T. Into nultifilamentary wires through a modified jelly roll (MJR) The formation of A15 Nb^Al by diffusion reaction was examined by heat flux differential scanning calorimetry of was used as «i fib corDponen t• An Al~*5wt"tlie a L lo v pr^pared by a powder metallurgy processed wire samples. The conventional casting process was forged and rolled into a sheet calorimetry technique provides the reaction rate ai « of 0.3 mm in thickness. The Nb/Al-Ge composite was prepared by function of time during a constant heating rate anneal. The wrapping the N'b mesh sheet and the Al-Ge alloy sheet around a P/fi processed Nb-fivt.%Al wires used 75-105 ym Nb end 5 um Al Nb core into a jelly roll form. The MJR composite was encased starting powders with an areal reduction ratio of 100,000 , in a Cu-Ni alloy tube o' which outer diameter was 43 nun. The as described earlier.'1' Three exothermic reactions were resulting composite was hydrostatically pressed and extruded observed between room temperature and 1000°C. Arrhenius Into a rod of 18 nun in diameter. activation energies were determined for each reaction by A ND bar r ie r was then Inserted between the MJR composite and multiple calorimetry runs at different heating rates. The the Cu-Ni jacket. The composite rod was swaged and drawn Into highest temperature reaction had an activation energy of 2.6 eV/aton, and was identified by x-ray diffraction as the jacket was etched o££ after the drawinc. The outer dlnnieteir of formation of A1S Nb^Al. The two lower temperature precursor the final wire was 1.0 mm. The cross sectional configuration reactions had activation energies of l.ZeV/atom and of the MJR composite was not appreciably disturbed by the fab- 1.4eV/atom. The precursor reactions resulted in the rication. Superconducting properties of the wire after differ- formation of a mixture of NbAl£ and a BCC phase. The ent heat treatment including a rapid quenching from high ten*1 implications of the phase formation sequence and activation paratures bv a continuous electron beam irradiation will be energies to annealing schedules for wires will be discussed. reported. * Also Dept. of Physics, H.I.T. * Supported by the DOE Basic Energy Sciences ++ Supported by the National Science Foundation * W.K. McDonald et al., IEEE Trans. i Magnetics, HAC-19 (1983) 1) C. L. H. Thiene, S. Poumhimi, B. B. Schwartz, and 1124. S. Foner, IEEE Trans. Magn. HAGj^l, 756 (1985). Session LE SMES I 9:45 a.m.-noon, Tuesday, August 23, 1988 discussed. This paper also presents test plant to Mature AC LE-1 losses in the SHES conductor to corroborate and improve the analytical models. AX OVESVIBV or Tin SHES rat Ptocuut: Til warm. TEAK'S FEESPECTIVS *, R. J. Loyd and T. E. Walsh, Bechtel National, Inc. - Superconducting Magnetic Energy Storage (SMES) will have Its flrat large-scale test with the * Work, performed under DM. Contract DHAOO1-88-0028 through Engineering Test Model (ETH). SKES Is a promising technology for electric utility load leveling (and system control), end Bechtel National, Inc. for military applications requiring high-power pulses of significant duration. The ETM will be designed to operate on both modes. The primary purpose of the ETM program is to LE-4 demonstrate full-scale SMES technology. A program that will culminate in operation of the ETH within five years Is In SMES COHmCTOK TEST MOCUH \ F. R. Huaon, place. This paper describes the Team's technical approach, B. Rochs, J. Zelfler, Texss Accelerator Center, and including current and planned activities during the two-year J. R. Purcell, Advanced Cryo Hagnetica - This paper presents component development and conceptual design phase of the an overview of the conductor test program for the project. Successful completion of the SHES/ETM will open the SMES/Engineering Test Model. The design and operation of the door to the largest application yet for superconductivity snd high current teat facility, at well as relevant sssoclsted by far the largest market for superconductors. techniques (i.e., low resistance joints, operation bclov 2 K) sre discussed. * Work performed under DHA Contract DHAOO1-88-0028 through Bechtel Rational, Inc. * Work performed under DRA Contract DNA001-88-0028. LE-5 rOVEt CORDITIOfllK STSTHf FOE TEE SHSS/EECIKEEIRC TEST MODEL \ B. E. Dick, L. H. Walker, J. L. Bo wen, General Electric Co. Drive Systems Operations, and T. E. Walsh, LE-2 Bechtel National, Inc. - An efficient, cost-effective system is being designed to convert and condition power from a SHES CUUKXT DIFFUSION EF/ECTS OH TBS PHPOtnMfCZ OF LA1GE coll (a dc current source) to utility grade 3-phase, 60 Hz H0R0LITHIC CORDUCTOSS, C. A. Luongo, B. J. Loyd, and ac. The PCS will also be designed to operate at high powers C. L. Chang, Bechtel Rational, Inc. - The technical and representative of inputs required by ground-based lasers being economic viability of SUES hinges heavily on the successful developed as part of the Strategic Defense Initiative. The development of a very high current conductor. This paper ETM will demonstrate SHES technology st full-scale. This describes a model used to assess tht stability potential of paper outlines a program of development, design, snd testing, large monolithic conductors. The model is based on leading to fabrication and operation of the PCS as a major two~diaensional, coupled thermal and current diffusion subsystem of the SMfS/ETM. equations. The model is bench-marked against experimental data and with results obtained with other models. The applicability of the cryostabllity criterion when current diffusion effects are present Is discussed and a number of conclusions are drawn. These conclusions vere fundamental to establishing the overall direction for design of the SKES conductor. Work performed under DHA Contract DNA001-8S-0028 through Bechtel National, Inc. LE-3 AC LOSSES IB THE SMES CORDOCTOI AXD COIL LE-6 STtOCT0H *, K. Gurol, General Dynamics Spsce Systems THEtMAL-HTDtAtTLIC SDULaTIO* 07 ULIUM EXTOLS 10* FtOH Division, L. R. Motowldlo, M. S. Walker, Intermagnetics A SmS COIL *, C. A. Luongo, S. J. Loyd, P. K. Chen, General Corp., and C. A. Luongo, Bechtel National, Inc. - The Bechtel National, inc., and S. D. Peck, General Dynamics Spsce SMES/EngineerIng Test Model nust operate under electric Systems Division - In a SMES coil, the stored energy cannot be utility and high-power military discharge regimes. AC losses dumped to an external circuit in the event of a quench. The •re of concern during the high-power discharge, when the rate energy must be dissipated Internally In the coll structure. of change of the magnetic field Is highest. The major losses To avoid local overheating and over-voltages, the protection will be coupling losses in the conductor, and eddy current system requires that, once a propagating normal zone it losses in the coll structure. The purpose of this paper is to detected, the entire coil be driven normal in a short time. discuss the AC heating models that have been developed, and to This piper presents the results of the thermal-hydraulic present preliminary results, The expression for the coupling simulation of heHUP expulsion during a coil protective energy loss includes the field change rate, effective transverse dump. The model and parametric studies used to guide the resistivity, and geometrical parameters for the conductor. design of the protection system and the Impact of protection Close proximity to the conductor can also Induce significant requirements on the overall system design, are discussed. currents to flow in the cold structure. A nodel has been developed to calculate such induced currents. The results show that Induced AC heating both In the conductor and in the coil structure can be reduced to acceptable levels. Design measures needed to achieve the required low losses are Work performed under DHA Contract D1U001-88-0028. 29 Session EF Millimeter Wave Technology I 9:45 a.m.-noon, Tuesday, August 23, 1988 Systea (EOS) and the Large Employable Reflector EF-1 (LDR). For these applications high quality, small area, large critical current density tunnel junctions PHASE SENSITIVE HETERODYNE RECEIVERS WITH SIS are required. Progress in the development of QUASIPARTICLE MIXERS.* M.F. Bocko, MJ. Wengler and Zhao Nan techniques for the fabrication of subvicron area tunnel junctions will be reported. Particular Zhang, E. E. Dept. U. of Rochester - It is possible to operate a mixer as a phase junction structures being investigated include mesa, sensitive linear amplifier by pumping with two local oscillators separated in crossline, and edge geometries. Using reactive sputtering techniques, NbN tunnel junctions with frequency by twice the IF and symmetrically placed about the signal frequency. 2 In principle a phase sensitive amplifier may detect a signal without adding any critical currents in excess of 10* A/c» have been Cabricated with VB values as high as 30 mV. Thtss Sis noise. We present a new formalism developed to describe two local oscillator tunnel junctions have been integrated with antennas mixers and we extend the quantum mixer theory developed by Tucker1 to and coupling structures suitable for mixers test in a calculate the Y and H matrices for the two LO SIS mixer. wave guide receiver at 205 GHz. Results of these tests will be reported. •Supported by the Air Force Office of Scientific Research *This was supported by NASA and SDIO/IST. 1 J.R. Tucker, 1979, IEEEJ. Quantum Electron., QE-15, pp. 1234-1258. EF-6 SNAP STRUCTURES WITH Nb-A10x-Nb JUNCTIONS FOR HH HAVE EF-2 RECEIVERS, An.B.Ermakov, V.P.Koshelets. I.L.Serpuchenko, L.].Fi- ll ppenko, S.V.Shitov, A.N.Vystavkin, Institute of Radio Enginee- NUMERICAL COMPUTATION OF TWO-PUMP SIS MIXER ring and Electronics USSR Academy of Science - High quality GAIN AND NOISE,* Zhao Nan Zhang, M.F. Bocko and MJ. Wengler, H. E snail area Nb-A10x-Nb junctions have been fabricated with Selec- Dept., U. of Rochester - In another paper in this conference Bocko, Wengler tive Niobium Anodlzatlon Process (SNAP). The influence of the preparation conditions on the junctions properties were investi- and Zhang propose to pump an SIS mixer with two phase-coherent local gated. The numerical calculations based on IVCs measured by da- oscillators to operate it as a phase sensitive amplifier. Phase sensitive linear ta acquisition system vere used to simulate the mixer performan- amplifiers measure one quadrature of an incoming radiation field and may have a ce. It has been shown that the "knee" structure on the IVC of refractory material junctions affect significantly on the sig- noise temperature for that phase which is less than the usual "quantum limit" of nal properties of the mixer. The experimental Investigation of phase insensitive linear amplifiers. We present numerical calculations of the gain the signal and noise properties for different types of the inte- and noise temperature of a two-pump SIS mixer for realistic I-V curves and grated SIS mixing elements have been performed in the frequency range 37 - S3 GHz; the mixer conversion loss (SSB) was as low investigate the requirements on SIS junction leakage current and imbedding as A dB at 45 GHz. The nixing elements consist of the odd num- impedances to achieve a noise below the phase insensitive linear amplifier ber of SIS junctions connected in series for RF and parallel for dc biasing have been tested. The dc bias wiring and IF fil- "quantum limit". ters of these structures were designed to provide tuning out of the junctions capasitance and thin film electrodes inductance. •Supported by the Air Force Office of Scientific Research The advantages of these mixing elements on traditional series array have been demonstrated. EF-3 OUASI-fARTICLE AND PAIR CURRENT STEPS OF JOSEPHSON EF-7 JUNCTIONS WITH RAOIATION NOISE IN A DC MAGNETIC FIELD. U. NB EDGE JUNCTION PROCESS FOR SUBMIU-IMETER WAVE SIS Jutzi, E. Crocoil. D. Orung. and 6. Kriflwr, Umv«r*itat Kirla- MIXERS.• W.CDanchi**. E.C. Sulion. P.A. Jamineu University of California it Berkeley. ruft* - Currant voltag* characteristics of a Jonphion function Space Sciences Laboratory and Physics Department; R.H. Ono, National Bureau of Stan- approximated by i long int*rf*ro*>tttr with many point functions dards, Boulder, CO - We describe a junction fabrication process that produces high quality according to the Wirthaawr thtory ar* simulated undtr th» in- Nb edje junctions of anas less than 0.2 \im2 on thin quartz (0.004 in.} substrates. This -fluanc* of a local oscillator it about half tht gap fr«Qu«ncy process utilizes a GCA Wafer Stepper for high resolution and high accuracy layer-io-layer registration. We have fabricated large numbers of junctions reliably with high quality I-V Uiti characteristics and with impedances suitable Tor use in SIS mixers for submillimeier astron- omy. Junctions produced by this process can be stored on the shelf with no special prcciu- lions for periods of more than two yean with an impedance change of less lhan 10% and are thermally cyclable. Currently these junction! are being used in an astronomical receiver having state-of-lhe-art performance in the atmospheric window centered at 345 GHz. With some improvements 10 the process it is possible to make junctions wilh areas sufficiently small for a*C=3 at 800 GHz. • Supported in part by the U.S. Army Reaearch Office Contract DAAG29-8S-K-O2S4. EF-4 •• Supported in part by the L.W. Frohtich Research Fellowship of the New York Academy NUMERICAL SIMULATION OF EXPERIMENTAL DATA FROM PLANAR of Sciences. SIS MIXERS WITH INTEGRATED TUNING ELEMENTS,* C.A. Mears, Qing Hu, P.L. Richards, U.C. Berkeley, and F.L. Lloyd. National Bureau of Standards, Boulder, Colorado — We have used the full EF-8 Tucker theory including the quantum susceptance to fit data on ALL NbN NANOBR10GES AS JOSEPHSON MIXERS. T.Natui, planar lithographed ma-wave mixers with bow-tie antennas and Z.Hani*. K.rUaasaki*. T. Taaash i la*. Coaaun icat ion Research integrated R? coupling elements.'»a Essentially perfect fits to pumped IV curves have been obtained. The deduced imbedding Laboratory, Hinistry of Post »nd Telecoaiuaicalions, adnlttances agree well with those Independently calculated from Kogasei, Tokyo 184. *Departaent oT Electronics. The Tech the geowetry of the antenna and matching structures when the nolofical University of Nanoki. Nasaoka 940 21 He effects of reflection at the hemispherical lens are included. Me find that the quantum susceptance is essential to the fit and type of all-NbM naitofar idges aith g«p structure in I V thus predictions of the mixer performance. The quantum curves. The ntnobridges had large resistance 10 103 £1. 3useep .ance Is especially Important In the production of steps veil defined gap structure at ~-4 BV, large IcR* products with 1< and/or negative dynamic conductance for junctions with of -^3 aV. and lo« excess current. The variation of !<• ly sharp gap structures. Comparisons between measured tnoden • ith teaperature of the nano'bridics »is quite veil de and s ilated mixer noise and gain are in progress. * Supported by the U.S. Air Force Office of Scientific Research The observed systematic fa I I of f of Ihe UR. product «ilh under Grant No. AFOSH 85-0230. 1 increasing resistance vas aceounted for by the transition Li Xizhi, P.L. Richards, and F.L. Lloyd, "SIS Quaslparticle state theory if an effective noise teaperature. T,*". of Mixers with Bow-Tie Antennas," Int. J. Infrared and 6±1.5 K aas •sssaed. The present nsnobridges shoa aliost Millimeter Waves, in press (1988). 3 Qing Hu, C.A. Mears, P.L. Richards, and F.L. Lloyd, ideal Joscphsoa response to lilliaeter wive radiation at "Measurement of Integrated Tuning Elements for SIS Mixers with 101 CKz. The voI I-pronounced current steps have been ob a Fourier Transform Spectrometer," Int. J. Infrared and served up to 2.5 aV. The IF peak in Josephson Bitting was Millimeter Waves, In press (1988). obtained up to the bias voltage of about 4 aV. The present mnobridjes are Hell suited to use in Josephson aixers. thanks to their sell defined gap structure at —4 aV and EF-5 large resistance, and their long tera stability. MbN/MgO/HbN SIS TUNNEL JUNCTIONS FOR SUBMM HAVE MIXER APPLICATIONS*, J.A. Stern (Caltech), B.D. Hunt, H.G. XADUC, W.R. HcGrath and S.K. Khanna (Jet EF-9 Propulsion Lab/Calt*ch) — We r*port on the HARMONIC MIXING IN A SERIES ARRAY OF SHORT SUPER- fabrication and testing of all refractory HbH/MgO/NbH CONDUCTING WEAK-LINKS," T. Matsui, H. Ohta*, and H. Inornate, SIS tunnel junctions for use as high frequency •ixers. These aixers are being developed for use in Telecomumcations, Japan, *The Institute of Physical £ Chemical future NASA Missions such as the Earth Observing Research, Japan, -- Series array of quasi-planar Josephson 30 junctions (QPJJ) were developed foe studying high frequency AC frequency rangB from 184GHZ to 1Q3GK2, wrilch Is emit tad from Jose oil son effect fl nd foe niixinQ ex pet iriments. Arrays of FFO into the strlpline. different aenea number from 1 to 14 elements were made of sputtered niobium films on a quartz substrate. Harmonic mixing of microwave and far-infrared radiation with a Josephson junction has important applications both for accurate frequency EF-14 measurements and for heterodyne signal detection in the Car- COUPLING OF ELECTROMAGNETIC RADIATION BETWEEN PLANAR mcrarQQ » In hinn^ordfir narmonio mixing witn & ooint contat^t JOSEPHSON JUNCTIONS. N Cirillo and I Kodena, Umversito dl Josephson junction, however, IF noise increases due to down- conversion from noise around all unrequired harmonics, and IF V. Fofllietti and R Uoiu, IES5 CNfi, Roma. Italy - We inveeti- signal decreases in mixings between unrequired harmonics and a signal, which distribute the signal energy to frequencies out of gate the coupling of microwave and millimeter wave radiation IF band. Moreover, many harmonicB and wide-band background noises likely cause a saturation in a small single Josephson junction, which reduce the efficiency of harmonic mixer. While, 11ttiocrophy usinp 1 JLJTTI reso Jut.100 chno^iu^ ffls<5 iflbnicflteu by harmonic mixing using a serieB array, signal—to—noise ratios can &3ndwi cties havinD current detisitics up to ^OOC A/c^ . the probably be increased by several order of magnitude. In our oxide barrier was grown following the st«[>s of H recently experiment• series arrays behaved in-phase like a single junction. It is sugested from experimental results that harmonic developed implementation of the Greiner technique A Kb-SiO- generation can be selectively heightened when the harmonic order Pblnflu capacitor is employed in order to coup]e the radiation is equal to a series number of Josephson elements. A new type harmonic mixing xs discussed, and a preliminary experiment of JOO nfr^ thichne&s 01 the SiC layer- is 3bout three orders of harmonic mixing betweeen 106 GHz and 6-12 GHz. is described. n^3^ni tude Del ow the copficitsntre or the sm9jio* junction In our* experiments the rad1st1 on i s generated by a Lonp Josephson ••Supported by Science and Technology Agency, Japan. Junction (LJJ) dc-biased on singular!t:es of the current-voltage EF-10 about b jjm apart from the LJJ. By observing the Josephson MICROWAVE DETECTION WITH JOSEPHSON JUNCTIONS, H. Reiger, the current-voltage characteristic of the small area junction Technische Universitat Munchen, Institut fur Hochfrequenztechnik - The performance of a Josephson detector may be calculated from we obtain quantitative indications about the quality of the the solution of the Fokker-Planck equation of the Josephson coup]ing. element In an embedding network. Voltage sensitivity ij and noise equivalent power NEP of the detector can be obtained by EF-15 means of the Fokker-Planck method. At 1 THz a t}^ of 105V/W and NOISE DRIVEN FLUCTUATIONS IN JOSEPHSON 1 1 NEP < IO'^W/VH? should be possible under realistic assumptions. JUNCTION RF GENERATORS/ P. Hadley , M. R- Beasley , and It Is shown, that the temperature of the microwave source has a Kurt Wiesenfeld,2 1> Stanford University, 2) Georgia Institute of strong Influence on IJU and NEP. Detection experiments have been Technology - It is well known that series arrays of Josephson made with Josephson point contacts at 40 GHz. The agreement junctions can phaselock and oscillate coherently. Such mutually between measured and calculated values of IJU and NEP Is phaselocked junctions have been proposed as rf generators in the mm-wave/sub mm-wave regime. Here we investigate the noise excellent, The best values obtained were ij =4.5*10 V/W and driven fluctuations of these Josephson junction generators. The magnitude of these fluctuations is strongly dependent on how close NEP=3-10" the system is to an instability. In the case of a series array of N junctions the relevant instabilities are multiple bifurcations in EF-11 which as many as (M-l)! symmetries of the solution are broken simultaneously. We calculate the fluctuations that appear at these SUBM1LMMETER WAVE GENERATION USING instabilities and from them determine the linewidth of the JOSEPHSON JUNCTION ARRAYS,* K-L. Wan, A.K. J»in and J.E. generators. Lukens, Dept. of Physics, SUNY at Stony Brook—It hii been • Work suppported by NSF-DMR and NSF-ECS. demonstrated that Josephson junctions placed at wavelength intervals along a properly terminated transmission tine can be phase locked so as to produce in-phase addition of the rf voltages along the line. Previously studied series biased arrays delivered only about 5nW into a 20fi load at EF-16 100GHz due to incomplete phase locking caused by the scatter in ANOMALOUS R.F. I5DUCED STEPS IK RESONANT JOSEPHSON junctions parameters.' To overcome this problem of parameter scatter, TUNNEL JUNCTIONS FOR VOLTAGE STANDARD MAINTENANCE,*U. Klein and the junctions in the array have been biased at the same dc voltage using a parallel biasing scheme. Results are presented for a parallel biased J. H. Hinken, TU Braun3chveig, F.B.G, - We have theoretically array operating at 350 GHz. For this array, the power delivered into a investigated the current steps in the I-V-characteristics of a 200 load on the chip is ~ 1/AV, which is dote to the value predicted for long Josephson tunnel junction driven by microwaves at the fre- in-phase locking of all the junctions in the array. The operating quency of its geometrical resonance. For thiB purpose we use a frequency of these oscillators is tunable over greater than 5%. numerical computation algorithm based on a lossy transmission line model of the Josephson tunnel junction to calculate the d.c, current density distribution. In addition to the fundamen- •Supported in part by Air Force SDIO Contract F1962886K0039. tal microwave frequency, harmonic contents of the tunneling cur- rent are considered as veil. The calculations show a strong U.E- Sauvageau, A.K. Jain and J.E. Lukcm, Int. J. of Infrared and asymmetric behaviour of the current steps vith respect to the Millimeter Waves, 5,1281(1987). quasi particle curve. Our detailed "studies imply that the exci- tation of higher harxonic waves grves rise to these anomalous r.f. induced steps. Due to the nonuniform d.c. tunneling cur- EF-12 rent density distribution the amplitudes of these current steps MICROMAVE OSCILLATOR USIKG ARRAYS OF LONG JOSEPHSOff usually are not larger than tOj of the critical current. JTever- JUNCTIONS, S. Pagano and F. Monaco, Ittltuto di Cibernetlca del theless, they are relatively large, because in long junctions Coniijlio Nazionale delle Ricerche, G. Costibile, DlptrtiMnto the critical current amounts to several milliamperes. These re- di Fisica, University di Salerno - He report on aeisureaents sults could be considered for applications to voltage standard performed on integrated luperconducting devices based on luiped maintenance. The calculations are very helpful in designing arrays of long Josephson tunnel junctions operating in the tunnel junctions with optimised step amplitudes. fluxon oscillation refiae (i.e. biased on the Zero Field *Supported by Deutsche Forschungsgemeinsch&ft (DFC) Steps). The electromagnetic coupling *ionj Junctions causes •utual phase locking of the fluxon oscillations with * corres- ponding increase of the eiitted power and a decrease of the signal linewidth. Such a superradiant state can be controlled EF-17 by aeans of the externally applied dc bias and aagnctic field. MODULATION OP THE PENETRATION DEPTH OF Kb The effect of the generated licrouave signal hat been observed AND NbN FILMS BT QUASD?ARTICLE INJECTION,* E.K. Track, on a nail Josephson tunnel junction coupled to the array via • M. Radparvar, ud S.M. Paris, HYPRES, Inc., 175 Clearfarook aicrostrip transiission line. This suggests the feasibility of Road, Elamford, NY 10623 - A novel approach to Modulating Use such a device as a local oscillator in an integrated alcrowave inductance of a superconducting aucrostrip is described. Josephson receiver. This approach could be tbe basis for nuawrous practical applications such as phase shifters and high frequency tuning eleawnts. The physical •echanJsaMt inToWed are quasipartide injection, gap suppression, and penetration depth EF-13 Modulation. In this contaxt, we have investigated the modulation of the penetration depth of Nb and NbN filas by INDUCTIVE COUPLING OF A FLUX-FLOW TYPE JOSEPHSON quasiparticie injection. To this effect, all-Nb and aU-NbN OSCILLATOR TO A STBIPLINE, K.Yoshida. J.Qin and K.Enpuku, SQUID circuit* are designed and fabricated, that allow Department of Electronics, Kyushu University 3b, Fukuoka 812, quasiparticie injection into the inductive eleawnt. This Japan - A theoretical and experimental study of the coupling injection is achieved by: 1. optical irradiation through an opening in a Nb reflective layer which partially Masks the of the f1ux-flow type Josephson osci11ator (FFO) to an rest of tbe circuit, and 2. electronic injection through a external atrlpline has been carried out to overco«e the large tunnel junction overlayed over the sdcrostrip inductance. inpedance mismatch between FFO and the 6D{? strfpline. As a The inductance is Measured directly frost tbe dependence of nethod for an efficient coupling and an impedance matching in the gate current on the control current of tbe SQUID, i.e. Bllllmeter-and submillimeter-wave lengths, we have proposed a the interference pattern. Penetration depth BMdulation is achieved with both method*. The awgnitude of the effect scheme whers the Josephson oscillator is inductively coupled varies from 10| to over 200%. These results and their to the strlpline via a thin superconducting electrode. A dependence on temperature and on the parameters of the theoretical modeling of the coupling section and a design of control mechanisa) (light intensity, aaraunt erf current the strlpline impedance-transformer have been Hade. By an injection, etc.) are presented and discussed. experiment to confirm these theoretical results, we have •Supported by U.S. Air Force (APSC) Contract Nunber succeeded in detecting an output powBr of about 10 'w in the F19628-86-C-0117. 31 EF-18 EF-21 DESIGN OF VARIABLE PHASE VELOCITY KINETIC INDUCTANCE INDUCTANCE CALCULATION SYSTHM FOR DELAY LINES AND THEIR MEASURED CHARACTERISTICS WHEN FABRICATED Br A SIMPLE Nb BASED PROCESS, G. K. G. Mohenwarter, J. S. SUPERCONDUCTING CIRCUITS. M. Hosoya. P.. Goto, cl al.. Nirtens, J. B. Beyer, J. E. Nordman and D. P. HcGinnfs, Research Development Corporation of Japan - This paper University of Wisconsfn-Nidison - Homo grams for the design of describes a method for calculating the inductance of superconducting kinetic Inductance delay lines were obtained by complicated 3D {3 dimensional) superconducting circuits. simplify(09 the governing equations for the phase velocity range of Interest, Delay lines based on niobium and its native In this method, current distribution is obtained by solving oxide were fabricated. Processing Involves only dc magnetron (he simultaneous linear equation which satisfies both sputtering and anodic oxidation. Hence, it is considerably Maxwell's and London's equations- Inductance is less complicated than previously reported techniques. A novel method was used to determine the rf characteristics of the calculated from magnetic energy caused by ihe current. lines. Results show wave slowing to less than 1/50 of the Hxtmpolations are used to reduce the computational velocity of light in free space by microstrip 1ines with resources and to increase the accuracy of the results. associated characteristic Impedances of several ohms. Phase Based upon this method, a CAD system was developed 10 velocity changes on such lines in pnysicat proximity of both, long Josephson junctions and normal conducting lines have been design superconducting circuits. The inductance of Investigated. The observed behavior as a function of junction complicated 3D superconducting circuits, which was dc bias suggests that these changes in the case of long unable to be derived except by experiments, can be easily Josephson junctions are mostly due to variations of the calculated by this system. Coupling inductance of a DC- inductance per unit length rather than quasi-particle Injection. Substantial phase velocity variations can be SQUID is calculated using the CAD system. The result obtained by utilizing a normal conducting strip in contact with agrees well wiih ihc experiment. fne line while allowing the inmedfate vicinity of the line to float thermally. The loss and phase velocity of the Hb based lines were determined as a function of bias conditions for both EF-22 methods. DIELECTRIC CONSTANT OF EVAPORATED SIO AT FREQUENCIES BETWEEN 13 AND 103 GHZ. H.K. Olsson, Physics EF-19 Dcpt. Chalmers Univ. of Tech, S-412 96 GOtcborg, Sweden, - The dielectric SUPERCONDUCTING STEIPLINB RESONATOR PERFORMANCE, constant of an evaporated thin film of SiO has been measured ai frequencies B. R- UcAroj, J. D. Adas, and G. R. *a«cer, Weatinghouse RJtD between 13 and 103 GHz. 9 experimental points were taken in this frequency Center — Tr&nsaiafion rcionttor Bcrtsurcaents which provide loaded Q valuci directly are used in several RF range by using ft Josephson tunnel junction to detect microsirip resonances. configuration!. Dne is an open aicroatripline with capacitive The Josephson oscillations delivered power to the microstrip cavity at each coupling which does not require ohaic contacts and another is the sore eonon sandwich line both on sapphire substrates. resonant step in the I V-curve. Higher order steps occurred for higher critical Resonators at 3 GBs and 0 CHi have been evaluated using currents in accordance with theory. The calculated dielectric constant had a niobiua, lead and ceramic circuits. Differences in loaded Q which are important to oscillator performance are described, frequency independent value of 5.5. This value agrees with results using other •ore importantly open loop phase noise has been evaluated for measurement techniques. resonators at 3 CHi and is compared to acoustic bulk mode microwave resonators. The spread in self phase nois* for acoustic resonators is compared to that for atripline- resonators with frequency-Q products in excess of 10 • EF-23 CAPACITIVE DISCONTINUITIES IN JGSEPHSON T!iANSMlSSU.fii EF-20 ta". P. Carelli. Universitd di L'AquJla, V. FogliPlti anrj THERMAL STUDY OF SEMICONDUCTOR-SUPERCON- 3. Leoni, 1ESS CNfi. fiorr.a. S. Pace. University di Salerno, Italy DUCTOR HYBRIDS*, E. Raicu and T. Van Duzer, Electronics Research - The results of a study of the dynamics of magnetic flux- Laboratory, U. C. Berkeley. 94720 - Superconductive devices show consid- quanta (fluxcnsj in Josephson Transmission Lines (JTL) having erable promise for making millimeter- and submillimeter-wave receivers because of the low noise and high conversion efficiency of the SIS mixer the analysis, based on the sine-Gordon Hami Roman fornalisr., and the frequency agility of the Josephson oscillator. Gallium arsenide IF is carried out by aperturboticn arialy^Js o»" two S^TTII*-infinite amplifiers operated at low temperatures have very low noise and may be an important alternative to Josephson parametric amplifiers. We have con- or~GpQj?ation of* fluxons alone two *JT1*& n QV1np one? (?xtr*c^ity irpe ducted an experiment to evaluate the thermal problems that would result if lopen circuit boundary conditions) and the other coupled via a GaAs amplifier chip were flip mounted via solder-ball connections to an th& capacitor to the other JTL. A system 01 nonlinear oiiit?ren"~ otherwise superconducting receiver on a larger Si chip. The GaAs chip is tial equations is derived for this physical configuration and modeled by a Si chip carrying a thin-film resistor used to dissipate the int^ffrated by ffieons oi Session MG NbTi: AC Losses and Stability 9:45 a.m.-noon, Tuesday, August 23, 1988 MG-1 MG-2 MAGNETORESISTANCE OF SUPERCONDUCTING CABLES FOR LOSSBS IN SUPERCONDUCTING WIRBS WITH INHOMO- ACCELERATOR KAGNETS. U. B Simpson. K Carber and A. K. GBNBOUS AND ANISOTRGPIC MATRIX CONDUCTIVITY OVER CROSS SECTION, E.N.Akaenova and E.Yu.Klimenko, I.V. Kurchatov Institute of Atomic Energy - Methods of calculating energy losses for multifilamentary wires at room temperature (295X) and the residual resistance with anisotropic and lnhomogeneoua conductivity of a ratio tRRR). the ratio of the resistance «t room tempera- matrix over the cross section are developed, in par- ture to that at 10K. Using this RRR and che "Kohler ticular, for wires with a cluster assembly. It is Plot", which gives the electrical resistivity of copper shown that in the case of filling the wire core r 32 tensile stress applied during nagnet fabrication. MG-3 * Supported by the U.S. Department of Energy / High Energy AC LOSS OF NBIl SUP ERCONOOCT I ^C VIRES HlH Physics ur.der Interagency Agreement No. DE-AI05-85ER i c f i elds whTi alternate current of d i f MG-7 qnonc i es nf O-2nilz r-r" i nptit ,sincr» DC bi-'.p fin EFFECT OF ROOM TEMPERATURE STRESS ON THE CRITICAL FPT" rid of tb^ effect nf surf-ice >-;irri ^r.Thi n is CURRENT OF N'bTi.* S. L. Bray and J. W Ekin. National Bureau of nccordrince with thp cone ID si nn drown bv Thompson 1 Standards • Measurements have been made of Che effect on ^t-- ! . rrom thp- i r "xneri mpnt. crri c<\ out to nrnnuro critical current of tensile stress applied at room temperature the AC losses i" NhJ'Ge cuperconductor, in low r to NbTi conductors. The results of these measurements have been nmrlitude alternate Heldr. 'Uo 33 estimation process. In order to calculate the transport current MG-12 losses It Is necessary to know the current distribution Inside the conductor CUBBEHT DISTR10LTTJOH AHD AC LOSSES IN TIGHTLY TWISTED A SM]1 twist pilch - one of the characteristics of AC MULTIFILAWXTARY SUPERCONDUCTORS. A.J.H. Hoover* and LJH van superconductors - gives rise to a current distribution In which de Elundcrt, University of Tucnte. D*p*rts«nt of Applied the central part of the conductor aay becoae saturated Phyalca, Applied Superconductivity Centre, The Netherlands - Such a saturated area will contribute significantly to the Tne dcvelopaant of superconductors for AC use has led to total transport current losses conductors with f llaawnts In the subalcron range, highly In order to Investigate these phenomena a numerical BodeJ. resistive aatrlx Material and a saa.ll twist pitch to wire based on Carr's contlnuua aodel. has been -Jeveic/ped. The aodel dluwter ratio. All these chmractcrlatlcs ensure low hysteresis Is valid for twisted BUHI filamentary wires having B highly losses In the filaments and low coupling losses In the utrix resistIve sKtrlx. ]t enables to calculate the current aattrlal. I.e. low amgneUzatlon losses. distribution In a aultlf1lamentary wire subjected to a A reduction of the ajujnetliatlon losses however. My lead transverse Magnetic field and carrying a transport current, to a situation where the transport current losses are a both Us*-dependent The influence of the twist pitch and the substantial part of the total losses. Therefore the transport location and density of the filaments on the magnetization and current losses should play an essential role In the loss the transport current losses has been investigated Session LF SSC II 9:45 a.m.-noon, Tuesday, August 23, 1988 LF-1 LF-4 A UNIQUE CABLING MACHINE DESIGNED TO PRODUCE RUTHERFORD- SSC DETECTOR SOLENOID, R.W. Fast, JH. Grimion, TYPE SUPERCONDUCTING CABLE FOR THE SSC PROJECT" J. Grisel. DOUR- METAL, J M. Royec aid R. M. Scanlia, Lawrence Berkeley Laboratory - Up 10 25.000 H.J. Kreba, R.D. Kephart, E.D. Theriot, M.E. Stone, and R.H. Km of keystoned flat cable most be produced for the SSC project. Staning from a Wands, Fermi National Accelerator Laboratory-A detector utilizing specificatioa developed by Lawrence Berkeley Laboratory, a special cabling machine has a superconducting solenoid is being diacuaaed for the been deufaed by DOUR-METAL, li hat beea designed to be able to mn at a speed Superconducting Super Collider (SSC). A useful field volume of conttpoadisf lo a maximum production rale of 10 m/min, This cabling machine is the 8.2 m diameter x 16 m length at 1.5-2 T (-1 GJ) is required. key pan of the productkM liae which COMUU of a precision turkshead equipped wiih a It haa been decided that all of the particle physics calorimetry variable power drive, a caterpillar, a dimensional control bench, a data acquisition system. will be inside the bore of the solenoid and that there is no need and • take-sp imiL The main feature* of the cabling unk to be described area design with for the coil and cryoatat be "thin" in radiation lengths. An iron nearly expat path length between spool and aucaiMing point for all the wires, and the yoke will reduce the excitation required and will provide muon possibility to rua the machine with seven] over- or under-iwistii« ratios between cable and identification and a redundant momentum measurement of the wires. These requirements led DOUR METAL to the choice of an unconventional muons. We have developed a conceptual design to meet these mechanical concept for a cabting machine. requirements. The magnet will vie a copper-stabilited Nb-Ti conductor siacd for a cryoitable surface heat flux "0.25 W/cm . *Thii work was supported by the Director. Office of Energy Research, Office of High A thermosiphon from a storage vessel above the cryoatat will be Energy and Nuclear Ftiycio, High Energy Physics Division. U.S. Dept of Energy, under used to prevent bubble stagnation in the liquid helium bath. The Contract No. DE-ACO3-76SF00O98. operating current, current density, coil subdivision and dump resistor have been choaen to guarantee that the coil will be undamaged should m quench occur. The axial electromagnetic LF-2 force will be reacted by metallic support links; the stsinlesa steel coil caae will support the radial force. The 5000 metric ton* of M ALTERNATE HCTHOO FOR DESIGNING 01 POLE MAGNET ENDS.' calorimetry will be supported from the iron yoke through a H.L. Pope, H.A. Grttn, C. Peters, S. Cispt, tnd C.E. Tiylor, trussed cylindrical ahell structure separate from the cryoatat. The Livrence Berkeley Laboratory - Siull bore superconducting coil and caae, radiation shield and stainless vacuum vessel would dfpoTe Magnets, such as those for the SSC, orten have problens be fabricated and cryogenics!ly tested as 2-3 m modules. These In the ends. These problem can often be alleviated by modules would be lowered into the underground experimental hall spreading out the end windings so that conductor sees less and connected together to form two, B-m vacuum modules. deformation. This paper presents a new procedure for designing dipole nagnet ends xhich can be applied to aagnets •1th either cylindrical or conical bulged ends to hive Integrated field nultipoles which Met the constraints Imposed by the SSC latice. The Mthod described here pemits one to LF-5 couple existing awltiparameter optimization routines (I.e.. INTEGRATED THERMAL ANALYSIS OF THE PRODUCTION MINUIT «lth suitable Independent parameter constraints) tilth a DIPOLE MAGNETS FOR THE SUPERCONDUCTING SUPER COLLIDER, computer code DIPENO, which describes the multipoles, so that * G. E. Hardy and S.D. Peck, General Dynamics Space Systems Division - A one can meet any reasonable objective (I.e. minimizing thermal model of a Superconducting Super Collider dipole cryostat was Integrated sextupole and decapole). This paper will describe developed lo understand the system thermal behavior of the dipolcs. The model how the computer method was used to analyze the bulged conical incorporates in detail all the heat flow paths in the cryostat, with the capacity to ends for a one-meter long model of an SSC dipole. mode! all steady state and transient thermal boundary conditions the cryostat is subject to during normal and upset conditions. The model predicts heat leaks to 'Supported by the United States Department of Energy under the cryogens of 25.4 watts per dipole toSOK, 2.64 watts per dipole to 20K, and Contract Number DE-AC03-76SF0OO98. 0.174 watts per dipole to 4.35K during normal operation, which compare favorably to the established heat leak budgets. The 4.35K value does not include synchrotron radiation. The heal leak to the cold mass is below the LF-3 budget at a vacuum of 10"* torr, but exceeds the budget rapidly as the pressure increases. However, with 10 layers of MLI on the cold mass, the budget value SECOND GENERATION SUPERCONDUCTING is met even at 10"5 ion. The heat leak in the cryostat was shown to be sensitive SUPER COLLIDER DIPOLE MAGNET CRYOSTAT DESIGN, to the gas pressure, the inner shield temperature and the MLI thickness but not to R. C. Niemann, R. C. Bouert, J. A. Canon, N. H. Engter, J. 'he thermal shield thickness, the thermal shield weld frequency or the emissivity D. Gonciy, E. T. Larson, T. H. Nicol, T. Ohmori+, Fermi of the vacuum vessel or shield. The model shows that the synchrotron radiation National Accelerator Laboratory,* Batavia, IL - The does not raise the temperature of the winding more than 0.2 K relative to the inlet Superconducting Super Collider, a propoaed colliding; beam temperature of the helium. Cooldown from room temperature to 55K is shown particle physics research, facility, requires -10,000 superconducting to take from 1.5 noun to 3 hours with flow rates of the order of 100-200 g/xc. dericei for the control of high energy particle beams. The Warmup to room temperature from steady state operating conditions takes "7,500 collider rinj superconducting dipole magnets require approximately 17.5 hours using two 5 KW heaters. Re-cooling of the winding cryoatata that are functional, cryogeaieally efficient, man following a quench occurs after about 3.5 minutes from 70K and 9 minutes from producible and coat effective. A aecond (eneration cryostat 300K. The heat rate to the helium in the yoke cooling channels ramps to .57 design haa been developed utiliiing the experiences gained during kW/m in 45 seconds with the windings initially at 70K. This heat rate changes the construction, installation and operation of aeveral full length lo 3.6 kW/m 2 minutes after quench for an initial winding temperature of 300K. The radial magnetic pressure on the beam tube peaks at 0.75 MPa while the (16.0m) firat generation dipole magnet modela. The nature of tangential pressure peaks at .37 MPa for a 0.3 second quench decay time. the cryostat improvementa it presented. Conaidered *re the connections between the 4.5K magnet cold maaa and its aupporta, cryogenic aupporta, cold mass axial anchor, thermal insulation • Work supported by Universities Research Association under U.S. and vacuum Teiael. The details of the improvements are Department of Energy Contract Number DE-AC02-76CHO3000-0I. enumerated and the abstracted results of available component and system evaluation* axe presented. LF-6 DESIGN STUDY ON FUTURE MXt-XKRATUK MAGNETS ISI\G LARGELY KRYSTGNED CABLES, K. (shibashi. K. Kaaezawa, A. Xatase. A. Tcrajiaa*. Y. Sakakibara*. Y. Funahashi*. II. Hirabayashi", Kyushu University, and "Mational laboratory for High Energy Physics (KKK) - I'roton synchrotrons for colJiders vill have a bc.is energy of 10 20 TeV in the. near future. Such an * Operated by Universities Research Assn. Inc., under contract with the Department of Energy accelerator have a smaller bcas size than TKVATRON docs, so that its superconducting Magnets need to have a ssallcr boaa pipe. + Visiting researcher from IHI Co., Ltd. Isogoku, Yokohama 235, Japan Use of a saallcr coil diaaeter lakes the roil structure coapiex. 34 Since ii quite l.irRi' nuaitn-r ol tenets are n-suin*d for n E. Perin and D. Leroy, CERH, Geneva, Switzerland C. Spigo, Anssldo Component!., Genova, Italy, collider, staple coil strui-turo is dusimd for easy «.ifinct CERN intends to order from Industry all magnets and auxiliary components for a future Large Hadron. Collider (LHC) to be production and f iHd EG-1 EFFECTS Of INTRTHSrC STRESS ON SUBMICROMfTER Hb/AlO^/Nb Arl , JOSEPHSOK JUNCTIONS0, T. Uamura and 5. Hasuo. Fujitsu Limited - "he intrinsic stress of sputtered Nb film *as investigated from the viewport of producing submicrometer Nb/AlOj/Nb frcn the def 'ection o* N'b-deposi ted Si substrates measured by peenmg effect o' *r and Mb particles during sputtering. He made »-ra_v di ffract ion measurements, and observed a shift in Pig.5 Changes in substrate deflection the lattice constant that was proportional to the stress. In during tib patterning, •t >•;., rt : before patterning; • • * : after patterning. plied Nb/fWO,/Nb junction electrodes fib electrode uO'ng ar SiO;? as a nask. We obtained the first high- quality junction characteristics for C. 7-um-square junctions reported to date. The- critical current density was 6800 A/em?, and Development Program on "Scientific Computing system," conducted ;jnder a program set. b> t.hr- Agency of Industrial w Science and technology. m-.;;rv of Internationa' Trade and Industry. Fig.3 Lattice constant versus Kb film stress. Fig.6 Changes in lattice constant prepared. during Nb patterning. :IO.A - before patterning; Sputtprin'J. • •• * : after patterning. shows t he Ar c o n t ent in fib f i 1ms ,iersus the stress. When a-.- TH5 suggests tr-e cofnpr ession at lo wer Ar pressures is caused by e 3 shows thfc ' a tt tee constant of Nb fi tms measured b y r.-\ray dTffr I«L A, i*hich is. 0.0* A s.tr.4tler than the valu i the ASTM cards. space patterns as shown in Figure 4. Figure S compares the deflection of f«b-deposited 5i wafers before and after patterning. Squares, cireles, and triangles m the figure are fi 1ms prepared at Ar pressures of 0.67, 2.3, and 4.0 Pa, which correspo^c to cornprp^^ive, stres5~»ree. ano tens^ ie ' i 1ms. Fig.4 Line and space patterns used to examine stress relaxation. patterning. The Stress-free film deposited at 2.3 Pa exhibits no change. Changes m *,he lattice constant for both eompressive and Fjg.7 I-V characteristics of 0.7-^m- tensile films are clearly observed. the changes ore toward the square junction. stress-free Nb deposited at ?.3 Pa, dnd are remarkable when the width V: 20 jjA/div, H: 1 mV/div. of lines and spaces are small. These results suggest that the fJb filr stress >5 rela«ec at the peripheries of fine etched patterns. EG-2 So far, »e have attempted lo produce small PJb/AlOv'Nb junctions, but A nU SILF-AL1CKI»C PROCIS5 TO*. WR0LX-H4FIK TUmU. only obtained junctions with degraded charactensties. The Nb JUKCT10H rAIIICATIOH, N. C. BlMiiTc and J. E. ETCttf, DcpartMBC electrode was deposited at an Ar pressure of 1.3 Pa. On the basis of of Material! Science and K«t«llurgy, University of Caabridga UK. films, deposited at 2.2 Pa, tc the junction electrode, Vt have developed a new protesting route for Nb/Al~O,/Nb whole- figure 7 shows the I-V charcaterist i c obtained for a 0.7-ym-square wafer *ub«tr«te», which offers tangible advantagea over those junction. Tor oufcm icrome* er Nb/AlO^/'Jb junctions, the high-qual Hy previously available. Thit route allows che preparation of junction characteristics ' Vr of 30 - 3^ nV ) were achieved. planar junction* with just two lithographic atepa: btae Table *Jb filn preparafon. electrode pattern, and counterelectrod* definition pattern. The Deposition: dc mag. sputtering 3 Ar pressure. 0.67 • A.I Pa _ after definition by plasau etching, and the area of the junction DC current: 1.5 A \ I j is defined by the self-Masking counter-electrode, so that the DC wattage: 360 - 230 V \ Deposition rate: 220 • 1*0 nm'min completed junction lies at thr edge of the base electrode. This -• ° nethod largely eliminates the capacitance and potential failure problems associated with overlap between the base and counter- 5, electrodes, and the expansion stress which results xrovt anodia— at ion around an isolated met A is greatly reduced, suiting this an Fio.T Sf .us Ar i- during sputtering. extreaely attractive alternative to edge junction technology for 35 high frtquency aixer application!. Junction! and junction arrays These results clearly show that anodi;ation spectroscopy i*. useful to prepared by thia route ihov • very high quality, and the characterize the u-Nb/A10x and Al/l-Nb interfaces, and to optimize the fabrication processes for high-quality junctions. simplicity and reliability of fabricating lull (<3un) junction! ages. An investigation of Modifications to this fabrication route which Che bate and counterclectrodei will be presented. figure 1 EG-3 PROCESSING TECHNIQUES FOB REFRACTORY INTEGRATED CIRCUITS,* John X. Priybyai, R. D. Blaugher, and J. Buttyan, Testingaouse tiS Center - Processing techniques ha e been developed to increase yields and uniformity in superconductor integrated circuits fabricated with refractory materials. An Nb At *-oxide •ight lavil proem m u»d to define a ground plane, ground Nb plane insulator, Josepheon junction base and count*r electrodes, a second insulator layer, suparconductor Figure 2 k ./ interconnections, resistors, and gold contact pads. Every —-— L, layer, except the gold, was patterned by reactive ion etching. . Nb— AlOx-Al A naw ruiator structure was dare loped that included an etch stop layer. The formation of polymers, which occurs with etch gases containing carbon, was inhibited by tha addition of oxygen to the plasm*. Reactive ion etching of insulator vias was accomplished with a mw gai that gar* good selectivity for silicon dioxide over niobium. The effects of sputter gas Nb pressure on the built-in stress is films of niobium, aluminum, Al Nb molybdenum, and silicon dioxide were measured. Stress-free films were obtained by adjusting tha gas pressure. Figure 3 •Supported in part by AF Contract F19628-86-C-0158 with RAJDC. EG-4 , _ ,—4— CHARACTERIZATION OF Nb/A10x/Nb JUNCTION STRUCTURE BY AHOOlZATtON SPECTROSCOPY*, T. rmamura and S. Hasuo. Fujitsu Limited - The quality of the Nb/A10x/Nb junction depends on the sharpness of Nb/A10x and Al/Nb interfaces. By measuring dV/dt vs V during the anodi zation of the Al/Nb interface, the interface sharpness can be diagnosed to some degreeJ) Me applied anodization spectroscopy to u-Nb/AlQ^-Al/l-Nb junction structures prepared with different layer sequences and thickesses, and characterized the u-Nb/A10x and Al/l-Nb Figure 4 interfaces so as to consistently produce high-quality junctions. Here, u-Nb and 1-Nb denote the upper and lower Nb, respectively. The u-Nb/A10x-Al/1-Nb deposited on thermally oxidized Si was anodized using an SiOj as a mask. A dV/dt vs V profile was measured under a constant current of 0.4 mA/cm', From the profile, the sharpness of the interfaces could be diagnosed with a resolution of 0.5 nm. The fundamental requirements for the production of high-quality junctions were c larified. Using an Al layer thick enough to cover the Nb surface of the lower Nb. we were able to consistently obtain a Al •-oxide sharp u-Mb/A10j, interface. At the Al/l-Nb interface, the Nb sharpness strongly depends, on the surface morphology and on the surface oxide of the lower Nb. When a thin native oxide, NbOx, is formed on the lower Nb, the deposited Al interacts with Figure 5 NbOx, and a sharp interface cannot be obtained. 1 /v_ 1) H.A.Huggins and H.Gurvitch, J. Appl. Phyn.. 57, ?103 (1985) Industry. Nb Al «-oxide Nb The u-Nb/A10x-Al/l-Nb junction structure was sequentially deposited 1n Ar prftitura: 4.0 Pa a vacuum run. Here, u-Nb and 1-Nb denote the upper and lower Nb. Nb Figure 6 and Al were deposited by dc-magnetron sputtering at an Ar pressure of ^—~/V— 1.3 Pa. The A10x barrier was a native oxide formed on Al in an oxygen-argon atmosphere. The junction structure, particularly the u- Nb/A10x and Al/l-Nb interfaces, was monitored by anodization spectroscopy. Anodization was performed through a window in a thin S1O2 passivation layer in an electrolyte of ethylene glycol and ammonium pentaborate. The sample structure is shown in Figure J. Figure 2 shows a typical dV/dt vs V profile obtained by anodization spectroscopy. The upper Nb is 30 nm thick, and the Al is 7 nm thick. In the figure, sharp u-Nb/A10x and Al/l-Nb Interfaces are observed. At the lower-Nb side of the Al/7-Nb interface, dV/dt is slightly decreased. This suggests Al diffuses into lower Nb to a depth of 5 nm. The sample was patterned by R1E, and its I-V characteristics were EG-5 measured at 4.2 K. The junction quality parameter Vm exceeded 50 mV. Figure 3 shows a prof 1le measured for a sample prepared by omitting CHARACTERISTICS OF VfRTICAIXT-STACUD PLANAR TCTOfIL the oxidation step. The A10x barrier was not formed between the upper JUNCTION STMCT01IS, M. G. ilaaure. E. I. Soewkh, G. W. Horrid, Nb layer and the Al layer. In the figure, diffusion between the upper and J. E. EY«tte» Department of Material.* Science and Nb and Al layers is clearly observed. This indicates that existence of the A10x layer is Important to form a sharp u-Nb/A10x-Al interface. Metallurgy, University of Cambridge UK. - Whole-wafer multilayer 1 Figure 4 shows changes in the profile for di fferent Al thicknesses. structure* consisting of vertically stacked A 2°3 tunnel Profiles measured for five Al thicknesses from 1.4 to 7.0 nm overlap barrier! separated by thin Nb layers have been deposited under in the figure. Arrows indicate the increase in Al thickness. When the Al thickness is less than 5.6 nm, sharp interfaces are not UHV conditions, with repeat distances ranging froai 10-50n«. obtained. This suggests that Al films thinner than 5.6 nm are not Using a conventional SNBP process, these structures have been enough to cover the surface of the lower Nb layer. fabricated into vertical series arrays. Good quality results When a native oxide is formed on the lower Nb prior to the Al have been obtained fro* such arrays, and their practical deposition, diffusion of Al into the lower Nb occurrs as illustrated application in test-wave mixers is being investigated. By in Figure 5. This suggests that a clean lower Nb surface is necessary to form a sharp Al/l-Nb interface. Figure 6 shows a profile for a sample whose lower Nb is deposited at vert ical arrays, we have been able to accurately analyse the an Ar pressure of 4.0 Pa. This dull profile suggests that the Al/l-Nb interface is also affected by conditions under which the lower Nb is prepared, and maybe by the surface morphology of the lower Nb. 36 Che effects of che deposition condicions. A technique for neurology - Both digital and analog auparccnducUv* circuit* electrically connect ing to intermediate Nb layers in vertical •ay aaplcy afe-circuit* ocaprlainj lvapad llaaail inducecra and capacitor*, m digital circuit* hav* a mad far U-c natuxte array• has been developed and is being uaed to investigate che aa tranafenan to aatch tha 50-da-iapadtnca caock-aavafotB effects of independent biaiing of intermediate layers. ganeraton to the nalativaly lo*-iap*danca Joaactwcn jwrticn elactronic*. An *n**iil* of tha analog uaaa of IrC circuits can ba found in th* ljitagrator aaction* of tna auparocrductlva tla- EG-6 intagratiiig oocralator. In both application* good circuit perfonanoe xvjuin*. capacitors with a a*all parasitic anunt NIOBIUM TRILAYER PROCESS FOR SUPERCONDUCTING cenductanoa. lhim work rapcata on tna fabrication of lov-loaa CIRCUITS. J. M. Murduck. W. Dozier. R. Sandell. J. Burch, C. luapad-alaaant auparoonductiv* oapacitora. Dang, H. Chan, A. H. Silver, R. W. Simon and A. D. Smith, TRW Iha baa* alactrod* of tha capacitors consiatad of a Space and Technology Group • We have developed an improved •EUttar-daposltad M> fila, mil* a 46-nrthick dialactric layar In situ trilayer process for fabricating Josephson circuits. By no* fcraad by a partial anodizatlon of tnla IUm. capacitors controlling a multi-layer artificial barrier of oxidized aluminum1, with lea* tangants of < 0.002 (at 1 Hfe) war* *a*ily fabrloatad 2 by dapoaitin? a aoft aatal countaralactroda such a* Bs or R>-ln- current densities from 10 to 6000 A/cm are reproducibly and *u alley. Howavar, froa th* point of viaw of circuit reliabili- accurately obtained. Junction leakage is low. with Vm values ty ard thanal cycling, it is prafarable to ua. an all-Ma typically 2 40 mV. Within TRW the niobium junctions are being lininaa. Unfortwataly, tha ahunt conductanoa of tha capacitors used for parametric amplifiers, A/D converters, VCO's, IR waa found to incraaa* vran tha avaporatad B> alactroda «** detectors, and digital circuits. In addition, TRW niobium junctions raplacad by aputtarad tt>. This IM attributad to tha ma— In have successfully been used in the NBS Josephson voltage tha W> fila and daaage to tha dialactric during tha ccuntar- standard. We will describe the fabrication process, and list dactrod* deposition. Urn affacts of the Af*mi+* f measured circuit parameters. for both rf- and dc-eagnetron-apjttarad ml avaporatad Ms coxaitaralectrodas on the n*n*n1t-cr mi wan studied. The [in an paraaatars wan cptiaixad to obtain 1M. Gurvitch, M. A. Washington, and H. A. Huggins, Appl. Phys. low loaa capacitcn with dialactric strength* of > 2x10° Lett. 42, 472 (1963). voits/ca. Th* ca of all-* h< raacrators (raacnant fraquency . 10 Hlz) fabricatad using this process wars in elrsss of 250. EG-7 LCH-I06S IUCB> EUWirr CMVCTPCRS KR SUmOONOJCTIVE INTEGRATED CIRCUITS,* H. Ehushan, J. B. Green and neet»nli is eyjiJtad by SDIO/IOT and imaged by RADC, Isncoa A. C. Anderson, Lincoln Laboratory, Ta*«ii In—It* Institute of MB, Mt. Session MH High Tc Superconductors: Critical Currents I 1:30-3:15 p.m., Tuesday, August 23, 1988 were measured and compared with both conventionally pro- MH-1 cessed ceramic superconductors and with metallic- TRANSPORT CRITICAL CURRENT PROPERTIES AND UNIAXIAL precursor-derived superconductors without silver. The criti- STRESS EFFECTS IN YBCO. fli. AND Tl BASED SUPERCONDUCTOR SYSTEMS.* J. W. Ekin, S. L. Bray. T. M. Larson, and N. F. cal temperature and critical current densities at 4.2 and 77K Bergren, National Bureau of Standards • The magnetic field were also measured and compared. 1. G.J. Yurek. et. al.. J. Metals. 1988. Vol. 40. No. 1. p. 16. been measured in several high-Tc oxide superconductors systems. Jc data on YBCO. Bi-based and Tl-based systems are conpared and Interpreted In terms of limitations on Jc resulting from veak links, pinning, and transport anlsotropy. The effect of trans- MH-4 verse unlaxlai stress on Jc in these superconductor systems vill CRITICAL CURRENT DENSITIES FOR THE HIGH TEMPERATURE also be discussed and described In terms of weak-link and CERAMIC SUPERCONDUCTORS YBa,Cu3O7 AND Bi2Sr2CaCu20 * W.C. intragranular behavior. McGinnis, T.E. Jonas, E.W. Jacob*, R.D. 'Boss and J.W. Schindler, Naval Ocean Systems Center -- A pulsed transport * Supported by the Offic of Na- ch and che National technique is uaed to iwaiure the critical current densities of Bureau of Standards. ceramic superconductors. Using low duty cycle pulsed techniques on specially prepared supples with low contact resistance allows one to determine the entire super/nonul phase boundary MH-2 without the probleas associated with staple heatinf. The results of these neasuretwnts on all hifh Tc bulk ceruics FLUX PINNING IN S[NGI£ CRYSTALS OF YBa^CtijO. LN FtEIDS studied to date can be interpreted in ttrat of two different UPTO40TESLA.P.H. KPS, J. van den Berg. C.J. van der Beck, critical current densities. One, determined by the midpoint of J.A. Mydosh, Kamerfingh Onnos Laboratory, Slate University the transition, shows very little suppression with current, 2 Leiden. The Netherlands, L.W. Rowland. A.A. Menovsky. giving values of Jc > 1CT A/CM at 77K for bulk saaples. The K. Kadowaki, F. de Boer, University of Amsterdam, The other Jc, determined by the R"0 point, is United by the Netherlands -To gel insight in the intrinsic pinning properties development of a "foot" at high current densities. The of the ceramic high Tc superconductors, critical currents have development of this low resistance foot, probably due to "weak been determined from magnetization measurements on single links" in the intercrystalline regions of the mattrials, varies crystals of YB&jCiijO? in pulsed Fields up to 40 T at 1.4 and according to the sanpl« preparation. Tha correlation between 20 K. The field was applied both parallel and perpendicular to critical currents, sintering conditions, and saraple morphology the crystal! ographic c-axic. Together with static magnetization will be reported, and the implications of these results far the experiments in 5 T fields for temperatures between A and 80 K a development of high current-carrying wires will be discussed. sufficiently complete picture is obtained about the possible origin of the flux pinning. Two models will be compared, one *Work in this area is being supported at NOSC by the NOSC based on the direct summation of grain-boundary contributions, Independent Research Program, the Office of Naval Technology the other on the collective effect of point pins related to the and SDIO. many small defects in the crystal as revealed by high- resolution electron microscopy. MH-5 MH-3 SIZE EFFECTS IN THE MAGNETISATION OF HIGH Tc POWDERS, A.D. Hibbs, FJ. Eberhardt. A.M. Campbell. Depamneni of CRITICAL TEMPERATURE, CRITICAL CURRENT, AND ME- Engineering, University of Cambridge and S. Male, CERL, Leatherhead • CHANICAL PROPERTIES OF METALLIC-PRECURSOR-DERIVED Powders hive been ground and sieved to give a series of samples of various SUPERCONDUCTING MICROCOMPOSITES, G.J. Yurek. W.F. Doyle. sizes. Magnetisation measurements show that the currents in the particles are flowing on a scale of at least 30 microns. This is comparable with the grain size H.S. Hsu. L.J. Masur, C.J. Russo, American Superconductor but much larger than twinned regions. This suggests that twin boundaries do Corporation. - High temperature superconducting microcom- not act as weak links. Current densities were greater than l(rA/cm2 at 4.2K posites are produced by oxidation of melt spun YbBaCuAg al- and t factor of 10 lowerin Nitrofen. In the regimes measured it does not appear that flux creep will be a practical problem. loy ribbons'. The microcomposite ribbons have rectangular cross sections, with typical dimensions on the order of 3 mm x 40 microns. During oxidation, silver is excluded from MH-6 the superconducting oxide and forms an interconnected, in- FLUX TRAPPING AND A.C. PROPERTIES OF HIGH Tr terpenetrating metal skeleton within the superconductor. SUPERCONDUCTORS, A.M. Campbell, FJ. Eberhardt and A.D. Hibbs. Department of Engineering, University of Cambridge - Measurements have been The exact microstructure is a function of the alloy composi- made of die penetration of flux into hollow cylinders of high Tc tion and processing parameters. The presence of the noble superconductors. This allows a wide range of parameters to be determined on metal phase vastly improves the mechanical properties of the same sample. Effects due to intergrain currents can be separated from those due to intragrain currents. Flux creep causes phase shifts. These can be mainly the superconducting ceramic without adversely affecting its attributed to flux creep in the weak links. Critical current densities in the grains electrical properties. The fracture toughness and strength of are very high, and the behaviour is similar to that of conventional superconducting ribbons with different microstructures superconductors. For practical purposes the most important parameter is the field at which Jc drops to half its zero field value. 37 Session LG SMES II 1:30-3:15 p.m., Tuesday, August 23, 1988 SUES, an extensive program of testing is planned. A broad LG-1 range of characterisation and manufactoring tests are to be performed on the conductor materials, "subscale* conductor GENERAL DESIGN FACTORS AND CONSIDERATIONS FOR SMES IN models, "full scale" conductor mockups and a proof-of- UTILITY/SOI APPLICATIONS, *B. Janes Lowe and R. Henslcr EBASCO principle coil. These models will provide significant Services incorporated-D.Coers, CBI. A general overview of the feedback into the conductor design and fabrication •iniwitiug various alternative SHES conceptual design candidates, the technical risk. critical Issues relating to the proposed Engineering Test Model component development and testing, and special factors that •Supported by Defense Nuclear Agency Inhibit certain candidate sub-systew selections are described. Contract DNA OO1-8B-C-OO27. Significant fabrication and constructfbility problems that must tie addressed In the coil engineering and 1n cryogenic systems in Phase II are discussed. LG-4 DESIGN FOB A SUPERCONDUCTIVE POWER CABLE FOR SHES, X. Qlan and R. L. Kuscom, Applied Superconductivity Center, University of Wisconsin - Superconductive cables are ' Supported by Defense Nuclear Agency Contract DNA-001-88-C-OOZ7 considered for use between a 5500 MWh Superconductive Magnetic Energy Storage (SHES) and power conditioning systen. These cables work In complicated magnetic fields which vary along LG-2 the length of the cables. High current and strong magnetic COIL C0NST1UCTI0N CONSIDEJtATIONS IN SUBS-BUI, cables• An optl.olzatIon tecnnloue to mlninixze tfiese niagne11c •D. T. Backwortb ud J. X. Itpp, W«atinfhouae KJtD Canter - A forces IB described. A searching method Is used to find the Duabar of coil dasigns and strut types hare baaD eraluated. A optimum distribution of the cables which greatly reduces the •et of four Major critaria including friction generation, coil nagnetlc forces on the cables. A conceptual design for the and conductor strains, sit* compatibility and cable Is presented. The peak operating current Is 230 kA. •anufacturing/assaably costs were usad to araluate «acn Three bundles of conductor each with a 1 CEA cross—section of concapt. These concapts w«r» furthar analysed with finite copper and Nl obiuni Tltanlum In a £. to 1 ratio is planned• A •leaent structural Models to accurately pradict the coil and large room temperature copper jacket Is connected in parallel conductor strains as a function of radial displacement of the with the superconductive cable for redundant operation In the strut support mymt*m. Thermal loading is modeled in event of loss of cooling of the superconductor. Calculations combination with tba electromagnetic loading and strut system of temperature rise versus time In the worst case where there displacement. Further study of aacb concapt will be completed Is no cooling Is presented. and will include extensions of the structural analysis to the full sise SIBS coil and additional Manufacturing calculations. LG-5 •Supported by Defense Nuclear Agency Contract DKAOO1-80-C-OO27. SELF PROTECTION OF HIGH CURRENT DENSITY SUPERCONDUCTIVE MAGNETS. H. A. Hilal and Y. M. Eyssa, Applied Superconductivity Center, University of Wisconsin - LG-3 Lightweight magnets using high current density conductors are required for space borne application as well as for mobile CONDUCTOE DBSIGN AND FABRICATION CONSIDERATIONS FOR systems such as tanks and Bhlpi. The use of external duap SOS-En, -E. S. Ortoli, J. T. Dedtrtr, and D. T. Backworth, resistors In this case Is prohibited due to the resulting high Wastingbouss UD Center - A total of twenty basic and voltage across the aagnet leads and magnet self protection Is derivatirc conductor configuration concepts ware generated for evaluation. Twelve pertinent qualitative attributes for the potential of having a self protected magnet. If a normal superconductor/stabiliser aaaeably were usad as the basis for region develops, the current transfers to the beryllium culling than concept!. Tba concapt configurations ware structure. Since the beryllium Is In contact with the analysed for stability and for AC losses under SDI discharge conductor, the entire winding temperature Is caused to rise. condition!. The analysis produced parameters for the This results In transferring more current in the beryllium conductor asssablias for comparison of configurations. Since which acts like a heater to force the entire winding to go the conductor is a coaponent judged to be most critical for normal. The dump resistor protection scheme and the self the technical success of both the BTW and the "full scale1 protection scheme will be discussed and compared. Session EH SQUIDs 2:00-4:30 p.m., Tuesday, August 23, 1988 large output voltage, no lipedance latching nor a EH-1 special low noise preamplifier ia needed for the read-out achese> Standard ICs for FM signal proces- A DC-SQUID WITH UNSHUNTED SUBHICRON JUNCTIONS NEAR THE aing can be used leading to satch DO^C slse electro — HYSTERETIC LIMIT EXHIBITING AN EXTREMELY LARGE dV/df - TRANSFER nics. Such DC-SQUIDs h«ve been aado of thin Kb, NbK, FUNCTION, E. Houwman, twente University, Netherlands; R.Cantor, and Nb.Ge fills, the highest sensitivity resulting BO H. Peters, M. Muck and *H. Koch, Phys.-Techn. Bundesanstalt, FRG far,for Nlobiui devices with a white flux noise near - A dc-SQUID with an extremely large dV/d|) - transfer function 10"' tf» /VTfV at 4.2 K. (<50 mV/4 ) incorporates a novel type of unshunted junction of submicron geometry exhibiting a current-voltage-characteristic near the hysteretic limit. Thus the voltage-flux-modulation /I/ K.Mueck, H.Rogalla, end C.Helden, characteristics show as well hysteretic and non-hysteretic be- Appl.Phys.A45,665(1968). havior dependent on the bias current applied. A detailed des- cription of the Nb-Sl N -Nb-junction fabrication process and a characterization of tfte'SQUID - including noise spectra with EH-3 only a small 1/f contribution - will be presented. LOW NOISE OPERATION OF A X SQUID IN A LARGE B REGLME AND ITS APPLICATION TO THE DESIGN OF A HIGH Tc SQUID, K. •Supported by the Federal Ministry of Economics by contract Enpuku, S, Xohjiro and K. Yoshida, Dept. of Electronics, BMHi 9303. Kyushu University 36, Fukuoka 812, Japan Lo« noise operation of a large-B dc SQUID has been demonstrated in the 8=2LI /* is a modulation parameter. L is a SQUID inductance, EH-2 I is a critical current and * is the flux quantum. Energy SIMPLE DC-SQUID STSTEM BASED ON FREQUENCY resolutions of the SQUIDs, c. Rave been measured for various MODULATED RELAXATION OSCILLATOR, M. Muack, E. Sodtke, B values up to 8=12. It is shown experimentally that the and C. Htldea, Iastitut futr Angev. Phyiik der energy resolutions of the large-B SQUIDs are as small as those Justus-Li•big-Univ. Giesaea, D63OO Gisssen, F.R.G. - of conventional SQUIDs with 6=1 if the present resistively- Mierobridgea with hyateretic I-V-eharaeteristie can shunted-inductance scheme is adopted. For example, the energy be operated ss relaxation oscillator* when connected to an R-L shunt /1/. A DC-SQDID configuration reaulta case 2=12(L=34OpH and I-37uA). where h is the Planck constant. if two such oscillators are incorporated in a super- irtese experimental results ficree Guantitatively witli theo— conducting ring. Operating such a SQDID with a suit- retical ones. Therefore, the present scheme enables the use able bias current leads to an output signal of the of the SQUID in a large B regime, while the coavention.il order of 10 aV whose frequency depends on the magne- design significantly degrades the performance of the large-B tic flux in the 3Q0ID-ring sodulo <£ . Due to this SQUID. 38 It is also pointed out that the present scheme The present system has performances enough to be used useful in developing the SQUID with high T superroiiducto: lor studying the biomagnetic field such as magneto-cardiogram and avoid noise effects. Baset ults, perform- magneto-encephalogram ances of the high T SQUID , 1. M.Nakanishi, M.Koyanagi et at; Jpn.J.Appl.Phys. 26 (1987) 1050 EH-4 2. M.Nakanishi. M.Koyanagi et at; Proceedings of the Biomagnetism CURRENT AMPLIFIER AND FLUX-CONSERVING AMPUFIEH DESIGNS '87 rn Tokyo USIHG AN EXPONENTIAL SQUID WITH A JOSEPHSON JUNCTIONS (JJ) SYNTHETIC INDUCTOR, H. Cershenson, Naval Coastal Systems Center - 3. M.Nakanishi, M.Koyanagi et al; Extend abstract of ISEC '87 in Tokyo A current ampiifier design based on the principle of flunon propagation in a nultijunction exponential SQUID has been investigated. In this design, the critical current of the Junctions is increased exponentially. The SQUID inductance is a JOSEPHSON JUNCTIONS (JJ) equivalent inductance. Current gain can be achieved by generating Tluxons at the low end and dissipating thea at the tiigh end where the load is located. Such an amplifier has the advantage of being compact and insensitive to external fields. The circuit is self-compensating to process variations of the JJ's critical current. Device performance is evaluated by computer simulation. Two parallel exponential SQUIDs with solitons being generated at the low end side by current injection can be used to duplicate flux fro* a high inductance coil to a low inductance oi-tput. Flux wiil be conserved because the phase difference between the solitons generated and propagated fro* the input through the two SQUIDs will match the phase of the external magnetic field at the input inductor. The sane phase will be duplicated at the output inductor. EH-5 corner cut from cube Fig.i (b) THE DC IMPEDANCE OF AN RF BIASED RESISTIVE SQUID, H. Seppa. Finnish Technical Research Center; R.J. Soulen. U.S. Naval Research Laboratory; W.E. Fogle and J.H. Colwell, National Bureau of Side view Standards - We have developed a model for the influence of the radio frequency signal (amplitude and frequency), the tank circuit (coupling and Q). and noise on the impedance of an rf biased R-SQUID. We have measured the impedance as a function of these parameters with an inprecision of 5 ppm and an inaccuracy of 20 ppm. We have also studied ihese effects as a function of temperature from 0.0IK to IK. The results compare very well wiih the predictions of the model. EH-6 DC-SQUID MAGNETOMETER SYSTEM FOR DETECTING VECTOR VALUE OF MAGNETIC FIELD. M Nakamshi, N. Kasai, M. Koyanagi. and. H Kado. Electrotechmcal Laboratory • We have developed a DC-SQUID magnetometer system for detecting 3 components of magnetic field (vector) simultaneously. The system is composed of 3 integrated DC-SQUID magnetometers located perpendicular to each other and each magnetometer detects magnetic 10 50 WO 500 WOO 5000 Hz field normal to its substrate. Configuration of the system is designed lo be suited for investigating effects of mutual interference between magnetometers. It is proved that mutual interference does not damage important performances of ihe system such as a noise property and a transformation factor of magnetic field strength to voltage. White noise level of each magnetometer is about 11 IT'N'HZ Transformation factor \ of each magnetometer is calibrated to be 6 16 X 10'" T/V. The present system has enough performances to be used for studying the biomagnetic field such as magneto-cardiogram and magneto- encephalogram. We have developed a DC-SQUID magnetometer system for detecting 3 orthogonal components of magnetic field simultaneously. We call the system as a 3-dimensional system. The system makes measuring duration short in measurements of the biomagnelic field. Fig.i Schematic figure of the 3-dimensJonai system. The 3-dimensional system is composed of 3 integrated DC- Fig.Z Noise spectrum density ol one magnetometer of trie 3- SQUID magnetometers that are developed as components of a multi- dimensional system measured in a ETL magnetically shielded room. ?1 While noise lave' is 11 fT/vHr 31 the freauency range between 40 Hi channel system as reported before''• . Three magnetometers are to several kHz. Increase of noise below 40 Hi is attnbuiable to attached on 3 surfaces of a reshaped cube perpendicular to each magnetic field remaining in the magnelicaily shielded roomfli Peaks other as shown in Fig. 1 (a). This reshaped cube is supported by a in the noise property at SO Hi and its harmonics are attnouiaoie to the power fine. Other oeahs are attributable to the vibration ol the Dewar stainless steel pipe as shown in Fig.1 (b) Three integrated DC-SQUID magnetometer are located at rotattonally symmetric positions around the pipe This rotationally symmetric configuration makes il possible to Fig.3 Dependence of output voltage of Ihe magnetometer on strength of applied magnetic 'laid is measured m order :o calibrate the distinguish the effect of the external magnetic field and that of mutual transformation 'actor of magnetic field strength ;o voltage of each interference among magnetometers on their performances. magneto meter of the 3-dimensional system. Magnetic field is >n0ucea by a test coit located under the Oewar. Distanca between trie coil and trie 3-dtmensional system can be aOiusteo. Line shows a calculated It is made clear that the mutual interference does not dependence ot magnetic field strength en distance. Circles snow measured dependence ol output voltage of the magnetometer damage important performances of each magnetometer of the system Vertical axis of output voltage is adjusted in order to fit circles to the such as noise property and transformation factor of magnetic field line. Factor ol 6 16 X iO-" TV (or adjustment corresponds To the strength to voltage Figure 2 shows the noise spectrum density of one transformation factor of trio of the magnetometers when they operating simultaneously Peaks are attributable to the external magnetic field and not to the mutual EH-7 interference White ncse ievef of 11 HV'JHZ IS the same as that of the magnetometer when it solely operates. The transformation factor of AN INTEGRATED DC-SQUID GRADIOMETER FOR one of the magnetometers is calibrated to be 6 16 X 10-11 T/V by test BIOMAGNETIC APPLICATION. M. Koyanagi. N. Kasai. K. ChinoneV M. coil Result of the calibration is shown in Fig.3. The transformation Nakamshi. S KosaKa. M. Higuchi". and, H. Kado. Eleclrolechnical factor is also the same as that of single magnetometer system. Laboratory, 'Seiko Insir. Inc . "Tsukuba University - We have fabricated 39 an first order off-diagonal derivative g radio meter integrated with a planar EH-8 DC-SQUID and pickup coil on a single silicon wafer as an element ol the EXPERIMENTAL LOCALISATION ABILITY OF PLA- 10 channel SQUID system. The planar type DC-SQUID consists of two NAR GRADIOMETER SYSTEMS FOR NEUROMAGNETIC MEA- superconducting loops connected in parallel, two spiral 15-turn input coil SUREMENTS, A.C. Bruno', V. Pizzella, G. Torrioli and G.L. Romani", Istituto di Elettronica dello Stato Solido, CNR, Roma, Italia - The en- connected in series on each superconducting loop, and a one turn couraging results achieved in biomagnetic localisation have given an ex- modulation and feedback coil. Two pickup coils of 6 X 6 mm? are traordinary impulse to the development of multi-channel SQUID systems, connected in series with input coils. The base line of the present although at present constrained to a small number of adjacent channels. The development of a large multichannel system requires the use of in- gradiomeier coil is 8 mm. The preliminary operation shows balance tegrating techniques, thus, suggesting the use of planar gradiometer con- better than 1000 ppm and the field gradient resolution of 4.6 pT/nWHz. figurations, instead of the usual axial ones. The objective of this work is to experimentally verify the localization ability of planar gradiometers, The further improvement of the field gradient resolution is expected by studing the spatial density of a planar array. The experimental setup adjusting SQUID parameters such as critical current and shunt resistors, consisted of a current dipote model (a pace-maker electrode} imersed in and SQUID electronics. The gradin-neter was operated in ambient a spherical conducting medium and detected by a planar gradiometer coupled to a rf-SQUID. The planar gradiometer was made of wire with a magnetic field. The magneto-cardiogram was successfully obtained. linear and quadratic geometry. The array simulation was made by placing the single sensor in the corresponding array positions. The localisation accuracy of the experiment was tested by using a four-channel system Our target is to develop the multi-channel DC-SQUID system with vertical gradiometers and a conventional localisation program. The composed of magnetometers or gradiometers integrated with DC-SQUID performance of the system will be tested also on human subjects. and pickup coil on a single chip for the biomagnetic application. We 'Permanent address: Department© de Fistca, PUC/RJ, R\o de Janeiro, reported biomagnetic field measurements by using the SQUID system Brasil. composed of integrated DC-SQUID magnetometers in the magnetically "and btituto di Fisica Medica, Universiti nG. D'Annuiuio", Chieti, shielded room1-2). The magnetometer could not be operated in the flux Italia. locked loop without the magnetic shielding. In this conference, we will report the first order off-diagonal derivative g radio meter operating in the laboratory ambient field without any magnetic field shieldings. This EH-9 RESPONCES OF THE HUMAN AUDITORY CX)RTEX TO PURE TONES g radio meter is developed as an element of the 10 channel DC-SQUID AND SPEECH SOUNDS UNDER ATTENTION: NEUROMAGNETIC MEASUREMENTS system with will be used in the hospital ambient field. WITH A SQUID, S. Kuriki, M. Hurase, and F. Takeuchi, Research Institute of Applied ElectriciLy, Hokkaido University - Measurements of neuromagnetlc fields using a SQUID allow local Figure 1(A ) shows the basic configuration of the gradiometer. detection of neural activities in the cortex of human brain. The pickup loops of 6 X 6 mm2 are separated by 2 mm. The bias current i Tie present- work is to study *nc magnetic responses to is fed through the resistor in order to obtain symmetrical current feed. different auditory stimuli of pure tones and short speech sounds under attention. A 1 kHz tone burst and a consonant- Figure 1(B) shows the photograph of the planar type DC-SQUID with vowel syllable /ka/, both of which had 200ms duration, were Nb/AI oxide/Nb tunnel junction of 3.5 X 3.5 urn2. The device was applied to the subject's ears binaurally in random sequences at fabricated by using the fabrication process developed for digital different intervals of 1.5-3.0 s. The subject was instructed to attend either tone or syllable, or to ignore the stimuli. superconducting circuit. Responses occurring in right and left hemispheres were measured separately with a second derivative gradiometer coupled to an rf SQUID. Both the 1 kHz tone and syllable /ka/ elicited clear We made preliminary measurement of the balance for responses having two main peaks of opposite polarities (Nlm and perpendicular lietds of one of gradiometers in a uniform Held. The P2m) at about 100 and 180 ms after the stimulus onset. Relative balance is better than 1000 ppm limited by the error of measurement. amplitude of the Nlm peak to the P2m peak was larger in the response to 1 kHz than in the response to /ka/. It appeared The field gradient resolution was determined by measuring the noise that attention affected the amplitude of the peaks in different spectrum density and the sensitivity measurement from the known field ways depending on the stimulus attended. The relative amplitude gradient in the magnetically shielded room. The obtained field gradient of Nlm to P2m was increased by the attention to the tone in the response to 1 kHz. but the increase was not clear by the resolution is 4.6 pT/nWHz. The resolution will be improved by enlarging attention to the syllable in the response to /ka/. the voltage modulation depth using the proper shunt resistor of each junction. About one order improvement of the resolution will be expected. The gradiometer was operated without unlocking even in the EH-10 ambient field. The magneto-cardiogram was successfully obtained. THERMALLY INDUCED FLUX NOTION OP MAGNETIC FIELD TRAPPED We thank H.Nakagawa, M.Aoyagi, I.Kurosawa. F.Shinoki and IN THIN FILMS, H.J. Goldstein, Naval Coastal Systems Center - A model is presented to investigate the thermally induced flux T.Endo for useful suggestions and discussions, and S.Takada, motion occurring for thin films cooled in weak perpendicuJar fields. The pinning data taken is in the underexplored region or Isolated flux lines. The data involves the change of Magnetization at the film's center, far away from edge effects, as a function of fit* thickness, temperature change, temperature Fig.1 Basic configuration of the first order derivative gradiometer (A), and gradient, and cooling field. For the save average temperature photograph of the planar DC-SQUID (B). change at the film's center, the gradient method of heating showed an earlier onset of flux motion and a larger amount of flux motion when compared to the uniform heating method. As the cooling field is increased, the onset of flux motion occurs at a lower temperature change and the total amount of flux motion dramatically increases. For thicker films, the onset of flux 2 mm motion occurs at higher temperatures and the amount of flux motion is substantially decreased. All the bulk samples tested showed zero flux motion even at higher cooling fields and larger temperature changes. The model incorporates the following features: magnetic pressure effects due to a magnetic gradient occurring outside the sample, the thermal driving force of a temperature gradient, changes In the penetration depth \ (T) of (A) the fluxoid and general Hcissner instabilities occurring because B is less than HCI. The applications and implications of these pinning results for thin film superconducting devices are briefly addressed. EH-11 DC SQUID THE FLUX MOTION OF SMALL MAGNETIC FIELDS TRAPPED IN SUPERC0NDUCT0H5, T.R. Clem, Naval Coastal Systems Center - A model Is presented bo investigate the oscillation of surface flux-line elements excited by sub-critical surface supercurrents In bulk superconductors. In this model, viscous and pinning forces countering the Lorentz force of the current are considered following traditional approaches for high current densities. However, the phenomena is explored here in a regime of current densities and field intensities much smaller than critical values and for frequencies lower than the microwave range. Basic assumptions and ranges of validity are discussed. The magnitude of the flux-line displacements as a function of the Lorentz, pinning and viscous forces is estimated. The model is applied to describe flux motion In multiply-connected geometries such as rings, tubes and toroids for the case in which the transport current is driven by magnetic field changes. Unlike the case in (B) which the flux motion is Induced by a constant current source, the current density is now a function of the magnitude of the trapped field. Expressions for the counter EHFs, the modified current densities and the power dissipations are derived and estimates are calculated. The implication of these results to superconducting electronics is discussed. 40 theoretical analysis and our experimental data impli- s EH-12 es that in the whi te noi se regioi; Ev * 1 iffli ted by the rionvanishing plasnu oscillations arising froo re- THERMAL ACTIVATION AND MACROSCOPIC QUANTUM TUNNELING IN laxation switching from the resistive to the- super- A DC SQUID. F. Sharifi, J. L. Gavilano, and 0. J. Van conducting state of the interferometer. In order to Harlingen, University of Illinois at Urbana-Champaign.-- We improve Ev. a balanced relaxation-oscillation-driven have measured the transition rate from metastable wells in dc SQUID haa been suggested and tested. An analysis the two-dimensional potential of a dc SQUID as a function of shows that much higher values of the H (up to 0.1 V/ applied flux and temperature. We observe a crossover from <$0) and better energy sen si ti vi ty can be obtained in thermally-activated escape to macroscopic quantum tunneling this way. at a flux-dependent temperature. We compare our results with computer calculations of the thermal activation rates and WKB-tunneling rates in the two-dimensional system. We find that the observed thermal rates are significantly suppressed, suggesting that the potential barrier for activation is effectively enhanced by the interaction of the macroscopic degrees of freedom in the device. He are also studying the EH-14 effects of dissipation on the HQT rate. DC-SQUID PREAMPLIFIER FOB DC-SQUID MAGNETOMETER. Yu.E.Zhuravlev, V.P.Koshelets, A.N.Matlashov, I.L.Serpuchenko, •Supported by NSF-DMR87-22080 and NSF(MRL)-DMR86-1286Q. L.V.Filippenko, Institute of Radio Engineering and Electronics USSR Academy of Science - dc-SQUID magnetometer with dc-SQUlD preamplifier had been designed and experimentally tested.The to- tal magnetometer noise had been reduced to the intrinsic noise EH-13 level of the input dc-SQUID and magnetometer cryogenic contain- ment had been minimized by using the dc-SQUID preamplifier.We INTEGRATED-RELAXATION'-OSCILLATION-DRIVEN DC 3 SQUIDS, S. A. fludoshnikov, i'u. V. Maslennikov, V. K. used two identical thin-film dc-SQUIDs with 15 ma area reslsti- Semer.ov, 0. V. Sriigir^v, and A. V. Vasiliev, Depart- vely shunted Nb-A10x-Nb junctions. Two types of dc-SQUIDs inter- ment of ?hy si os, Moscow Sr.ate Uni versi ty - We have connections were investigated: through resistor and separating fabricated and investigated sinple and reliable r»la- capasitor, both were connected in series with coupling coil of xation-oscillation-driven dc SQUlDs with flux-to-vol- the dc-SQUID amplifier. The value of the resistor was chosen ne- tage transfer factor H = 3W3*e up to 1 mV/4n ^nd ar that of the dynamic resistance of the input dc-SQUID. The lY internal energy sensitivity Ev = U-* 1)*10- J/Hz first type of preamplifier circuit had flux anplification near at frequencies above x 10 Hz. Supplied with the 50uni- 20 dB in the wide frequency band. The designed dc-SQUID magneto- wire 20-turn input cail an*i b en* pick-up loop the meter with dc-SQUID preamplifier had a coupled energy sensitivi- SQL'ISs providpd Harriet i<-* field sensitivity close to ty s 5-1CT" J/Hz in the band from 10 Hz to 30 kHz and 100 dB ^_i^->» T/U_*/* Comparison of the results of a (6 ; 3)* T/Hz dynamic range. Session Ml High Tc Superconductors: Bulk Properties I 2:00-4:30 p.m., Tuesday, August 23, 1988 different compositions were prepared, including TLB.iCu.,0 , MM "IBaCaCuO , TIBaCaCu O , Tl»aCaCu,0 , TlHa.Ca-Cu"0y, TIBa CaCu*O Tl Ba C^uy0 , and Tl BaJcS Cu 0 r^p^ettv?- H:CH-TC SUPERCONDUCTING CLASS-CERAMICS BASED ON THE ly. t)ne of' the supercondifc t inn phases displayed *n onset Bl-Ca-Sr-Cu-0 SYSTEM, T.Kooatsu, R.Sato, K.Imai, K.Matusita, temprr.iture !22K ^nd a midpoint 119K which was stable a and T.Yamashita, Nagaoka University of Technology High-Tc reproducible. Resistance in thi> sinfje phase TlBaC 41 treatnunt. X-ray mieri.-dif!Y(ict(-Efctry MI-6 fletprrairif} tht1 crosc-cpctionui conf i •. f THE NHNUF4CTURISG PROCESS *ND PROPERTIES Of '.• OXYGEN KINETICS AND SUPERCONDUCTIVITY IN THE HIGH Tc sintering YBajCu-jOjj, the rates of both densi fi cat ion and grain growth are highly dependent on the OXIDE YBa2Cu30R *, O, F. dc Lima, R. F. J.irdira, S. Cams,, and composition and quantity of liquid phase which are I. Torriani, Institute de Fisica - UNI CAMP, 13081 Catnpinas, SP, present at the sintering temperature. The weight percentage of low mwlting phase required to effect Brazil - Several small bars were cut from a parent sample of the sintering properties is far less than that which YBa.Cu.O., prepared by Che solid diffusion method. Following, is observeable by x-ray diffraction and is thus difficult to quantify. In this study WR have used these bars were used for oxygen extraction under v. uura, in careful DTA measurements to determine not only the temperatures between 300 9C and 550 9C. X-ray analysis shows a amount of liquid phase present but also to estimate the composition of that phase as a function of gradual transformation from the very pure superconducting phase calcining temperature. (*«7.0) to the very puie semiconducting phase tx-6.3). Tc. *Supported By Basic Energy Sciences Division of Department of Energy. plateau around 70 K for 6.6* x£ 6.8, though a very sharp transition (A T - 1 K) was observed for the parent sample at MM 2 SYNTI JL I- i'l desorption are under way for the samples of Y.Ba-Cu 0 , as well as for samples of Y.BaCuO. and BaCuO- . Results and discusskn stii Kl-'-t r .• Corf... - A;; * Work partially supported by FAPESP-SP and CNPq, Brazil. MI-8 W* n*v.* L-.-.-T, ti/it.« ih'ih COMPACTED 1-2-3 CERAMIC POWDERS TREATED AS Hi/',, SrCO3, CJCOJ omi CuO p. u.J.-j s, ly Xhi- LI|-1 I m i /,i t i SUPERCONDUCTING COMPOSITES*, E. tf. CoLlings, A. J. Marltvorth, and K. R. Marken, Jr., BATTELLE COLUMBUS DIVISION, Columbus. ,1'Jtlltior. of somi- c ] emt-til. h. TUf 1. "twr^U-iisii •. r • Oh 43201 - Strong similarities h*ve been observed between the rcagnecization field- and temperature dependences of fine- ii- th« syiit hi'Ris uf d 'iinql- fifufii- «itll tinjh T,. .'v. i \ the case of Cu/SbTi, and between "subRralns" in the case of :.-mfj.-r,jt ur- <- t- ?•' "Ci. Tt»»- >.f, nn.-i KPMA .ir,,i!/s.-H ni>J :M- 1-2-3, causes the respective assemblies to exclude flux in the manner of a solid block of superconductor. Then at soir.e- v (ot tin- su|J*-rcor;(iucl ivity n.tl !.!»• hi [*".r [II-LS-, » ii'f. what higher applied field strengths (but scill below Hr\) the filaments and "subgrains" behave, respectively, like super- conduc£Ln£^ a^^re^aces. In this re^ioe, temperature—dependent •lilt1,, The cfl.T.-tii of t tn- nJLJ.tir.n o! som. *-;.-mt-r,T BSCCO h,»v: b-.-i: studn-ti if. -cjf-r T u ir.vc-nlin.itf.' 'lie vary strongly with temperature especiallv for t > 0.7. The (-.•OS i hi 1 ) t.y that siidi »l**mi-ni «'..ii>iljii'5 hiuli Tr. phtis relative dM/dH temperature dependence Is calculated for ion at MgO or ZrO- !o •!••- BjSrC C^Bteriiil whicn would otnerwise be expected to exhibit a sharp SYNTHESIS OF A HIGH ?r S.IPt.HC MilHJCT I Nr, HUASE magnetic transition at Tc. IN Hi-Sr-Cd-Ckj-f' SVSTEM * Research sponsored by BATTELLE and the U.S. Department of Energy, Division of High Energy Phvsice under Contract No. DE-AC-2-B6ER40296, st:i hi.-;1! r i-: MI-9 DENSIFICATION AND GRAIN GROWTH IN GdBa2Cu30x , R. W. McCallum, M. A. Noack, J. D. Verhoeven, K. No, Ames Laboratory, Iowa State University, T. Hatsuraoto, National Research However, it tiiis ri-.l b*-fr. r'-f-.r'.-d 'tut d si'Kjl.- j.hnr..- ^t Institute for Metals, Tokyo, Japan - While extensive ,'wgh Tf, w,is suo.--M.duUy h-,-r-, -JT-S I zi-d. We tinv n^.-r. T,: studies have been made on the microstructure of B SrCO YBa2Cu^O» as a function of processing parameters, of i2°i' i- C.iCO, ,ir«i CuO fxj.fie-rs, by t.n- -JJ-L , r-, /.j- very little work in this area has been done on the remaining 123 compounds. Experiments on GdBa2Cu30x have shown that, in comparison with an identically calcined YBa2Cu3ox material, densification and grain growth take place at much higher temperatures. These experiments will be discussed in detail. rii=r. '_)•:.• .-••jir.ixiBil ;or:. jr '.' • h i :t Z\-II- *.- iviv- r r Supported By Basic Energy Sciences Division of the i: • hi-- syf' (I"SJ :? of .i s:r, 42 A:877C-25hr C: BiSrCaCu2Oy(11l2) B:650C-5hr D.(1112).1wf/.MgO E:(1112).lwf/.ZrO2 > In UcrJ 60 80 100 120 WO TEMPERATURE(K) /.o 60 80 100 120 UO TEMPERATURE (K) for UiSrCaCu-,O snitt red ,it B7'°C [n arid 8r.0°C for Mir for BiSrCaCu-,O added lwt%MyO and ZrO2 sintered at BT5°C for 25hr will describe experimental findings, specifically, the micro- MI-13 structure before and after glazing and the transport current den- DEVELOPMENT OF TAPE AND WIHE PROCESSES FOR HIGH-Tc SUPER- sity before and after glazing. The second part of this paper will CONDUCTORS," L.R. Hotowidlo, J.O. Beardon, B.C. Giessen, B. Avit- report on a systematic investigation of the densification and zur. H.C. Kanithi, R. Haldar, G.M. Ozeryansky, S. Rangaswany, and critical current of Bi-AI-Ca-Sr-Cu-O wire processed by powder tech- 6.A. Zeitlin - y-Ba-Cu-Oxide Superconducting tapes are initially nology. Some key processing parameters for efficient densification prepared by plasma spraying onto an inconel substrate. Coating are (1) the wall thickness of the sheath, (2) the reduction taken thicknesses are in the 250-500 urn range. A very thin and narrow per pass, and (3) the angle of the die. The effects of these para- region at the surface of the plasma sprayed tape is subsequently meters on densification and critical current density will be reported. melted by an electron beam and followed by a final oxygen anneal. The electron beam "glazing" develops certain interesting micro- •Supported by Department of Defense structural features such as neit-textured grains. This article Contract XD33615-BB-C-2806 Session LH Magnets for Physics 2:00-4:30 p.m., Tuesday, August 23, 1988 LH-1 operation will b* presented. TOWARDS A I M LOrJG, HIGH FIELD Nb3Sn OIPOLE MODEL MAGNET OF THE • Operated by Universities Research Association, Inc., under tLIN-CERK COLLABORATION FOR THE LHC-PROJECT - DEVELOPMENT AND TECHNOLOGICAL ASPECTS,by Dr.S.Wenger ar\Q Or.F.ZerO&in, ELIN A.G contract with th« U.S. Department of Energy. and Dr.A.Asner, CERN "or possible future LHC superconducting magnets in the 3-10 T range two main technologies are envisaged- a) Use of NbTi cables, cooled with superfluid helium LH-4 and o) Use of high field and high current density Nb3Sn cable STUDIES OF TIME DEPENDANCE OF FiaDS IN TEVATRON according the "wind and react"-method, cooled with 1iquid SUPERCONDUCTING OIPOLE MAGNETS, R. W. Hanft, B. C. Brown, rie 1 ium at 4'2 K. The present paper reports on the progress D. A. H«rrup, M. J. Law", A. D. Mclnturff, M. J. Syphars, achieved in the development of a 1m long, 5 cm aperture Fermi National Accelerator Lab* - Using tha Farm!lab MTF nio3jn Qipole rrj3Q.net to 3e ffi&ut? according to tne wi no a no production measurement system, studies of the time dependanc* react" method. Electromagnetic and double compression of the fields in 6m superconducting Tevitron dipolas have bean mechanical structure computations will be treated, the latter studied in tin* ranges from 100 to 10s seconds. Using a high bemg backed by measurements on a full cross-section mechanical spaad magnetometer in a vertical Dinar system, studies of the mode' anil fully confirming computations. Results of short time dependance of fields in short, iron-free Tejvatron Dipolas sample measurements on nowel Nb3Sn cables up to fieldes of 10 T have been made in time ranges from 1 second to 10^ seconds. r ana overall current densities beyond 300 A/mm wi 11 be Relations among harmonic field components and dependance on reported, the main technological developments discussed and the excitation parameters such as ramp rates, temperature, excitation levels >nd ramp history are used to understand the mechanisms for magnetic field variation. Availability of many Tevatron magnets has allowed this study to find some magnets where this effect is observed in "symmetry unallowed" as wall LH-2 as "symmetry allowed" harmonic components. OPTIMIZATION OF fflJLTIVIRECOI L ENDS HAVING 45 DECREE BENDS.* C. H. Morgan. Brookhavt-n National Laboratory - The Multivire process is a proprietary method of applying chin *Operated by Universities Research Association, Inc., under wires to a flat substrate An application is superconducting magnet windings for an assembly of four different rnultipole contract with the U.S. Department of Energy. coils called the "Corrector" to be used in the proposed Helativistic Heavy Ion Collider1 (RMC) at BKL. The current Mult iwi re process does not permIc & change in direct ion of the LH-5 wire other than 4_ degree. An analytic expression is given for EXPERIENCE DURING SERIES PRODUCTION OF THE the harmonics of coil ends in which the 'i5 degree bends lie on SUPERCONDUCTING HERA DIPOLE MAGNETS, C.-H. DuStmann, straight lines. Used in a computer program, this expression H. Fors ter. D. Bonmann, Brown, Boveri Company FRG - facilitates positioning the lines r,f bends In order to minimize A production flow chart for the series production unwanted harmonics. of the superconducting HERA dipoles at a rate of one magnet per day is presented. Some of the major problems which occured during the series production of the HERA magnets and their solution will be Energy. discussed. LH-3 LH-6 TIME VARIATIONS OF FIELDS IN SUPERCONDUCTING MAGNETS MANUFACTURE AND TESTING OF -9 6 5 km SUPERCON- AND THEIR EFFECTS ON ACCELERATORS, D. A. Herrup, DUCTING CABLE FOR THE HERA DIPOLE MAGNETS, R.K.Maix, M. J. Syphors, D. A. Edwards, R. P. Johnson, A. V. Tollesfcrup, D.G.Salath6, Asea Brown Boveri Ltd, Zurich, Switzer- R. W. Hanft, B. C. Brown, M. J. Lamm, M. Kuchnir, land; S.L. Wipf, DESY, Hamburg, FRG and M. Garber, A. D. Mclnturff, Fermi National Accelerator Lab* - The time Brookhaven NL, Upton, USA - The specification of DESY dependence of magnetic fields in the superconducting magnets for the superconducting cable of the HERA magnets set of the Fermi lab Tevabron has been published. A field variation chal lenging requirements. During contract negotiation of order 1 Gauss at the aperture radius is observed. Studios the crxrj.t^i>c3l curr&nt to bt gijdranceed W3s increased on both full sized Tevabron dipoles and prototype magnets have from 7265 A to 8000 A at 5.5 T and 4.6 K. The cable, been used to elucidate these effects. Explanations based on built up of 24 strands (0.84 mm0) has a wedge shaped eddy currents in the coil matrix or on flux creep in the cross section of 1.67/1.2B x 10.0 mm,to be maintained superconducting filaments are explored with these tests. m a tight tolerance band. Demanding was the goal to Measurement results and techniques for controlling the effect keep the cables critical current within the limits of based on new laboratory tests and the latest accelerator _^ 2% . - In order to ach leve optimum invariability in 43 critical current of the individual strands the NbTi- confined electrons on some magnetic surface, and the electrons are base material was ordered within a smaller tolerance slocastlcally heated to multi-keV energies. There Is some band than usual (47.5 +. 1 wt%) and the manufacturing evidence that the ionization rate scales with the plasma density, prescriptions for extrusion, drawing and annealing and that the plasma density cut off limit should Increase as the were fixed with narrow tolerances for the whole pro- microwave frequency is increased, necessitating magnetlc fi ej d duction. The results of measurements on all strands strengths commensurate only with superconducting elements. In showed that the critical current varied within +. 5* order* to stuoy those pr*oce336Si a superconducting rolnlmuci B around a mean value of 450 A at 5.5 T and 4.2 KT Thus structure Tor a variable frequency ECR source, the SC-ECR project strands could easily be distributed to cabling plans at MSU/NSCL, is unoer construction. The electromagnetic design with a tolerance band of ± 2% around 10800 A at 5.5 T and cryogenic engineering or the magnet for the SC-ECf) will De and 4.2 K. - Additional variation was introduced due presented. to different deformation during cabling. By adjusting the cabling machine for each production accurately •Supported in part by HSF grants PH?37-008i6 and Michigan State the deviation of the cables critical currents was University. decreased from 8600 A + 5% to 8800 A + 3ft. The means being well above the specified 8000 A. -Statistics of the HERA cable production will be presented including investigations on degradation and cabling quality. LH-11 A 17 T NbTi-Nb3Sn SUPERCONDUCTING MAGNET WITH LOK-PURITV HOLMIUH CORK , L.Z.Lin, K.W.Li, G.Y.Lin, S.Han, X.S.Li, L.G.Yan, Institute of LH-7 Electrical Engineerin*, Academia Sinica, Beijing, FIRST INDUSTRY MADE SUPERCONDUCTING China - High Magnetic field faciIities for research Measurement in sciences and materiaJs have been QUADRUPOLES FOR HERA.* R. Auzolle. J. Perot. J.M. Rifflei. required for years in China. At present efforts are CEN Saclay, A. Fokkcn, O. Peters, S. Wolff, DESY Hamburg,- being concentrated on the development of coiIs for After four prototypes have been made and tested, several high nagnetic field. In cooperation with the 'contracts have been placed in industry to fabricate the 246 institutions which could produoe the quadrupoles needed for (he HERA machine at DESY multi filamentary Nb3Sn eondurtors with qui te good performance, a 14 T NbTi~Nb3Sn superconducting (Hamburg). Three European firms were selected and are magnet system ui th 31 mm bore has been construeted now working on magnet and cryostat fabrication. The and tested at the Institute of ElectricaJ contracts include a "present" of a few collared coils and Enginesring, Academia Sinica. The n&gnet aystem cryostats in order both to allow the firms to learn the work and to DESY to test the capability of the firms before going Nb3Sn coiIs. Two different cross section Nb3Sn to mass production. Mass production of collared coils has wires usi n« the bronze method made by Baoji Institu- te of Non-Ferrous Metal were chosen for the outer already started and mass production of cryostats should Nb3Sn coil with 80 mm bore and a 44 Kate. R.A KvtMnn, C.H.E. Zeyen*. B. ten Haken. L.J.H. van practical magnets the BQCOS {KZ/U field Is approximated de Klundert, University of Twente, Applied Superconductivity with 30 superimposed concentric solenoids with a diameter of Centre, En&chede. the Netherlands and t-O Instltul Laue about B cm. The magnet length Is about 1.5 a. The basic Langevtn, Grenoble, France. — Neutron Laraor precession relative line integral homogeneity of 10' Is further spectroicopy use the particle splits as an energy Indicator. Improved to 10 by two In-beam correction colls. This The technique Is based on the condition that neutrons having advanced homogeneity level means that after 10* precessions the sue energy, have the sue number of precessions while the precession angle Is still well defined without using travelling through a certain precession field. The energy tedious correction procedures. This Improvement opens new loss due to the Interaction of neutrons and sample Is applications of neutron spectroscopy. In this paper we will related to the difference In the number of Laraor discuss design and constructional aspects of the precessions as determined by both precession Magnets, one spectrometer magnet system. before and the other after the sample. As a consequence the technique require that for all neutrons In a diverging beu [1] C.H.E. Zeyen. P-C. Hem, R.A. Hartmann, L.J.H. van de the path Integral of the modulus of the Magnetic field must Klundert, "Optimal Neutron Larmor Precession Magnets", be constant. The principle solution of the shape of optimal Proc. MT-10 Boston 19B7. IEEE MAG-? (1988), paper DA4. •^recession magnets was described elsewhere [1]. In the Session MJ Nb3Sn Processing and Properties 3:30-5:30 p.m., Tuesday, August 23, 1988 of significant design parameters. Required heat treatment MJ-1 conditions will be addressed. Critical current performance and the A.C. loss characteristics will be presented and compared with COMPOSITE CORE Nb3Sn WIRES WITH ENHANCED STRAIN other Internal-tin processed conductors. TOLERANCE. R. Flukiger, U. Specking, S. Gauss*, Kernforschungszentruii Karlsruhe, Instttut fur Techniscne Physfk, D-75OO Karlsruhe, FRG(* present address Hoechst AG, D-6000 Frankfurt, FRG) - Powdermetallurg1call,y processed composite core MJ-4 Nb*Sn wires, a new type of wires with filaments containing DUCTILITY ENHANCEMENT IN UNREACTED INTERNAL- Sn Nb3Sn THROUGH LOW-TEMPERATURE ANNEALS, »M. J. controlled normal conducting Inclusions (Ta and NbTI) have recently been developed on our laboratories (1). These wires Strum, L. T. Summers, and J. R. Miller, Lawrence Livermore show an enhancement of Jc in the low field range (B < 12T) with National Laboratory - A lack of ductility in unreacted wires at room respect to binary Nb^Sn Mire. At 10T, highest values of temperature could lead to damage during certain required processing steps such as twisting, cabling, and coil winding. Measurements of 4.5 x 105 A/cm2 were reached in the A15 layer. I.e. > 50X higher the tensile ductility of internal-Sn, Nb3Sn in the as-received, than for the binary wire. A further Important property of these unreacted condition revealed relatively low elongations to failure (1 wires Is the considerably enhanced precompression. Measurement to 1.5%). Therefore the effectiveness of low-temperature anneals at on 12 different composite core wires yielded « values between 200 C to enhance the ductility of as-received, unreacted wires was 0.5 and 0.61. This enhancement Is essentially due to the low investigated. The RT elongation to failure is significantly improved thermal contraction of the Ta Inclusions with respect to Nb^Sn. by moderate anneals, increasing to 10% after 23 hrs. at 200 C. This Ta contracts much less than Nb^Sn on cooling resulting 1n an effect is attributed to the dramatic reductions in RT yield strengths in the annealed wires. Fracture surfaces reveal increased adhesion additional internal compression. The combination of higher between the Sn cores and the surrounding Cu in the annealed mechanical reserve and higher Jc at 10-12T may be advantageous condition as well as an increase in ductile void coalescence as the for fusion magnets, as will be discussed. failure mechanism within the Cu. Preliminary results on the influence of these anneals on the thermal reaction response in (1) S. Gauss, w. Specking, F. Weiss, E. Seibt, J. Xu and R. Flukiger, Adv. Cryo. Eng,, Vol. 34 (1988) 843. prestrained wires will also be discussed. lvU-2 •Work performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under INFLUENCE OF CYCLIC PUMPED DIFFUSION ON THE contract number W-7405-ENG-48. MORPHOLOGY AND MICROSTRUCTUREOFAI5 LAYERS IN BRONZE PROCESSED MULTIFTLAMENTARY WIRE, B.A. Glowacfci and J.E. Evens, Department of Materials Science and Metallurgy. University of Cambridge, U.K. We report the development of cyclic heat treatment schedules MJ-5 to regulate tin supply and A15 compound growth in a bronze processed NbjSn METALLOGRAPHY AND SUPERCONDUCTIVITY IN THE BRONZE- multi filamentary composite. In the range 500°C to 800°C the ratio of the PROCESSED Nb-Sn ADDED CERIUM AND CERIUM-TITANIUM, diffusion coefficients for tin diffusion in bronze and Nb,Sn changes strongly Liu Chunfang, Zhou Man, YanR Zhaoling, Baoji Institute with temperature. At high temperatures A15 compound growth is sufficiently for Non-ferrous Metal Research, P.O. Box 71, Baoji, Shaanxl rapid to deplete the neighbouring bronze matrix of tin, while at low temperatures di- compound growth is very slow but tin diffusion in the bronze remains ;ampl< significant. We have used a new reaction method of cyclic pumped diffusion (CPD) to achieve near uniform A15 reaction layers on filaments throughout the .th at 70CTC cross-section of a multifilamentary composite. A detailed investigation of the spatial variation of the lattice parameter during reaction in filaments and in the [multaneously added with Ti and Co were less than Ti addi- bronze matrix has enabled us to optimise the time and temperature for successive ion samples, but larger Chan others. It was detected that reaction cyles. A 61 x 61 filament Nb - 7.5% wt Ta - bronze composite reacted here was Cc? element in thu Nb-Sn layer for the Co addition using CPD in the range 60O-80O°C shows a compound thickness variation amples. The average relative content of Sn in thp Nb-Sn between the inner and outer filaments of-8%, while the same composite given a a ye i~ s for the Cc audition samples was nl thcr than t na t conventional isothermal heat treatment at 700°C shows a corresponding layer thickness variation of -40%, The consequences of the CPD reaction method for all araount of Cc addition and pure Nb-Sn was not obvious. the design of composites containing tin reservoirs will be discussed. creasing Ce content, Jc decreases slightly in low-fie Id. can be expected that 45 Session MK High Tc Superconductors: Thin Films I 3:30-5:30 p.m., Tuesday, August 23, 1988 nonconlacting metliod first used by Schamhorst' 10 evaluate Jc in films li MK-1 has the potential of being used as a routine diagnostic loo), permitting MICROCHARACTERIZATION. ELECTRICAL TRANSPORT. AND Further experiments to he performed on an unperturbed sample A small SURFACE STUDIES OF HIGH TEMPERATURE SUPER- pancake coil pressed against the film surface induces shielding currents in CONDUCTING FILMS MADE ON MgO AND ZrO2 . • D. K. Lathrop. the film when Die coil is driven willi an audio frequency current When (lie S. E. Russck, R. A. Buhrman , Cornell University — We have grown high induced current density exceeds the critical value a nunlinearity in the (espouse of the driving call appears. We find thai current densities as l»w quality YBa2Cu3O7 films Dn MgO and Yttria stabilized Z1O2 (YSZ) wilh a 2 High Pressure Reactive Evaporation technique. The HPRE process allows us as MmOA/cm in a MHK)A film can be resolved hy this method. to grow in situ superconducting films at temperatures as low as 575 C. The Subsequent measurements of Jc by the direct method yield values in best films have been grown at 625 - 650 C. The resultant films on (100) reasonable agreement with the 1 ion-com act ing method. Calculations of MgO are highly oriented with the c axis perpendicular. TEM studies have the proportionality between coil current and ihe current induced in ihe superconductor will be presented along with our optimum experimental shown that the Him substrate interface is very clean and that the realization of the technique. superconducting film registers extremely well with the underlying MgO lattice. The films on (100) YSZ are highly oriented with varying amounts of c 1 and a axis perpendicular regions depending on deposition conditions. TEM Peter Scliamhorst, Phys. Rev B. I, 4275 (1970) results have shown intcrfacial layers between the YSZ and superconductor. We have fabricated microconstrictions, weak link structures, and transmission lines on superconducting films on YSZ, MgO, and MgO on Si substrates. MK-5 6 2 Critical current densities are greater than 10 A/cm on both YSZ and MgO DISSIPATION IN HIGH Tc THIN FILMS. at 4.2K. Our standard RTO processing yields contacts with resistances P England, T. Venkatesan. T.L. Cheeks, H.G. Craighead, C.T below JO"8 fl cm2. Films on MgO show excellcni uniformity in resistivity Rogers, S.W. Chan. Bellcore; X.D. Wu and A Inam, Rutgers University. -- Present methods of fabricating YlBa1Cu-iO1~h thin and critical currents across the substrate and on all features down to 2 micron films by pulsed laser deposition result in films that are line widths. We will report on electrical measurements on these devices. We multicrystalline with grain sizes of typically lfim, or are quasi- also will report on surface studies of these films and the effects of rapid monocrystalline. with no discernable grain boundaries, according thermal oxidation used during our processing. The results of microwave loss to whether the deposition is carried out at high or low measurements and IR reflectance measurements on our high Tc films will be temperatures respectively. We have studied the electrical characteristics of both these types of material. We find that the 1- presented. V characteristics of the granular material follow the rule r Va(/-/C)'' ' over at least six orders of magnitude in voltage, at all temperatures and magnetic fields. In addition, x(T) changes •This research has been supported by ONR and NSF. sharply from x=l to X"2 at the temperature at which lc becomes finite. This behaviour can be explained quantitatively within existing theories of composite superconductors; in particular, it MK-2 represents a phase ordering transition in which the coupling energy SUPERCONDUCTING PROPERTIES OF MAGNETRON between nearby grains forces the system into a state where the phase on all the grains in the system is the same. The non- SPUTTERED HIGH Tc FILMS CONTAINING OXIDE COMPOUNDS OF granular material has a much sharper resistive transition (~ IK) YTTRIUM, BISMUTH, OR THALLIUM,* R.T. Kampwirtb, J.H. Kang, and and larger critical current (>]0 Acm~2 at 77K }, and its electrical K.E. Gray, Argonne National Laboratory - We have used multiple source characteristics are more consistent with flux flow in conventional magnetron sputtering to prepare films of Y-Ba-Cu-O, Bi-Ca-Sr-Cu-O, and Tl- superconductors. Ca-Ba-Cu-O, on (100) MgO. ZrO2-9%Y2O3 and (100) SrTiO) substrates. Y- We anticipate that both types of material will be of technological Ba-Cu-O films grow best on SrTiOs with mostly an a-axis orientation. significance. We hive shown that the granular material shows Stoichiometry, particularity the Ba/Cu ratio must be within 2% of the correct promise as a weak link element and as a photodetector: and the value to obtain narrow AT transitions. Conversely the 80K phase of Bi-Ca-Sr- non-granular phase will find applications where the high critical t current density is essential. The significance of our findings Cu-0 films grows best on MgO substrates and has a predominant c-axis regarding the dissipation mechanism for these applications will be orientation. The requirements on composition are less stringent, however the discussed. annealing temperature must be held within a narrow range around 865°C to obtain the best films. Preliminary measurements show a high anisotropy in the critical field slope (-15), as might be expected from highly oriented materials. MK-6 Tl-Ca-Ba-Cu-O films have been grown on MgO and ZrOj substrates with Tc EFFECTS OF IRRADIATION INDUCED LATTICE onsets above 120K. We will compare the optimum preparation conditions and DISORDER IN SUPERCONDUCTING YBa^Cu3O7 FILMS * superconducting properties, including Tc, ATC, JC(H), dHc2/dT (parallel and perpendicular to film surface), of all three compounds. P. SCIIMITT, II. ADRIAN. W. GERIIAUSKK, AND K. STUMPF; Phys. Insiitut. Friedrich Alexander- l'nivcrsititl, Erwin-Rommel-Str. I, D-8&20 Krlangen. KRG. We report the preparation of thin films of the high-Tc>supercoiidur tor VWfljO^O- •Supported by the U.S. Department of Energy, Basic Energy Sciences-Materials by dc-magnetron sputtering onto room-temperature substrates and the effects Sciences, under contract #W-3l-109-ENG-38. of structural disorder iudroduccd by irradiation wilh 25MeV 1(iOions on MI- pel-conductivity and electrical resistivity, lly a suitable heat treatment films with T/s around 90K and transition widths of .IK could he reproducing pre- MK-3 pared on SrTiOa substrates. The metal sloicliiometry which was investigated by OBSERVATION OF STRESS RELAXATION W Kutheribrd-barksrattnring-analysis proved lo be of utmost importance for the su- perconducting properties of the films. In case of AI3O3 substrates secondary neu- Ba2YCu306+4 FILMS, A. Davidson, N.F. Pedersen. A. Palevsk:, and M. Scheuermann, IBM Research Division. Yorlctown - We have ob- tral mass spertroscopy revealed significant diffusion of AI into Ihe films leading to served a mechanism of stress relaxation in thin polycrystalline films reduced Tr's, broad transitions and resistance ratiofi Hit = pliOOK)/p(lO(ih') of less than I, whereas for SrTiO substrates Rfi > 1 is observed The up deposited on yttria stabilized zirconia (YSZ)- This observation is im- 3 per critical field B j(T) of high-T(-films measured up to G Tesla is linear with portant because YSZ seems to be otherwise a very good substrate, f dBcljdT = -2U/T. Irradiation wilh 25 MPV oxygen ions, which produce lai having a minimum of chemical interaction with the films. Our films lice defects by the displacement of atoms due to the transfer of kinetir energy were deposited by DC sputtering from metallic targets, with ex situ via Coulomb-interaction, leads to sensitive linear reduction of T, and a linear heat treatment afterward, to yield zero resistance at 85 K, and transi- increase of p[ 100 K) wilh flucnce. The sensitivity of Tr to irradiation depends on tion widths of a few K. The relaxation is observed at high temperature, the quality of the film and varies between £/c = -307/ and -t)O/V for an esti- near the orthurhombic-tetragonal transition, in the form of large elec- mated concentration of displaced atoms ofl %. For high-Tf-films HfJ(T) remains trical noise signals with singular low frequency events. The voltage linear with a nearly constant slope for defect induced 7'<-depressions of ].'• K. A spikes are seen both with and without current through the sample. SEM comparison with conventional superconductors .shows that on a normalized seal** micrographs show that these films developed pot-hole like voids a few the defect sensitivity of T, of V/fcijCujOr is situated between the Chevp-l phavo microns in diameter. Films kept longer at the structural transition and the A15 compounds. Possible mechanisms for the defect-induced degrada temperature developed more voids. We suggest that each voltage spike tion of superconductivity will be discussed. observed at high temperature is caused by the sudden eruption of one pot-hole. Films deposited on MgO substrates showed significantly * Work supported by the Buudesminister fur KorschutiR und TecluioloRie. fewer pot-hole events. This work underscores the need to minimize the temperature and duration of heat treatments in device processing, par- MK-7 ticularly on YSZ substrates. MK-4 INDUCTIVE MEASUREMENTS OP CRITICAL CURRENT -m,iuitiutturdi (.iidrauicmutb ui 1 rja2*-u3'-'7 DENSITY IN SUPERCONDUCTING THIN FILMS. J.H. Claassen. Naval importanmportant influence on their physical propertiespropert . Four-axis x-ray diffraction methods have been used to characterize textured and non-textured phases in Research Laboratory - Critical current density lJC) is one of the most hd h b d hri important parameters for characterizing a ceramic superconducting film. A several YBa2Cu3O7.fi thin films deposited on single crystal SrTiOj. Doth "a" direct measurement of J involves patterning of the film, preparation of and "c" axis textured films have been analyzed by tilting ihe specimen and c observing the distribution of YBa2Cu3O7-5 {102} plane x-ray intensities over low-resistance conlacts. etc. These procedures can degrade the 05% of the Ewald hemisphere. Several films were found to contain non- properties of high Tc films. Complications due 10 edge effecls make such cpitaxially onented phases including YBa2Cu3O?-6, YjBaCuOs and BaCuO;. measurements difficult to interpret. We discuss refinements of a The existence of stacking faults, such as those caused by the presence of extra 46 Cu-O planes in YBa2Cu3O7.fi, can sometimes manifest itself as a broadening can LM- si rang ly 1 nt ] Liencod Ijy io'iai van a*, KJUG iri • i:*> a izt' and and shifting of diffraction peaks. Consistent with the x-ray dau, the stacking diBtritiut lui! of graiTUi. qra in boandar inn . arn t rusupy , coirpoai - faults are readily seen in HREM images. t ion till-, ft troasuMiiy tochtuquf capable ot probity ttiw super* conducting proper!. ie:; in import ant for rht- baeic undfret finding • This work was supported by the NSF-MRL Program through the Center for of the high-Tr raait-ridls and tlii»ir d«?vu:o and mjcrooi-lpc* ronici: Materials Research at Stanford University. provide important irformation on ihe local supcrconducting pro parties of h AQh-Tf^ f 1 lnH . TnO pj-inciplt? u' ttiju R;(?T n^^'! I :n. i?u * MK-8 iinf^Q1 including tnc* spa* lal r*i»itJlMiion Illicit. O^r I'X^i** irT't '.t. h INVESTIGATION Jt HIGN-TC-FILKS BY LOW TEMPERATURE SCAN- results obtained with YBaCuO f 1 lms demonstrate 'fid' • • • 1" ..1. NING ELECTRON MICROSCOPY, R. Gros-,, J. Bosch, and R. P. Huebe- of this roe*.hod. frobabiy this new t<^chri^ii>- 1 • 'rrdod lor t he spat la i I y reyol ved obscrvationof fl.>: 1 1 i'ui flux floi 47 Session P-3 Plenary III Materials 8:15-9:30 a.m., Wednesday, August 24, 1988 an expanding Market was accompanied by very significant P-3 Improvements of the Materials engineered for specific purposes. Niobium-based conductors and films became dominant in both THE STATUS, RECENT PROGRESS, AM) PROMISE OF "large- and small-scale" applications. Today, the dramatic SUPERCONOOCTING MATERIALS FOR PRACTICAL APPLICATIONS, J. H. increase In transition temperature of the oxide materials holds RoweH, Bellcore - It Is now 25 years or so since the first promise for a much greater commercial use of superconductivity. serious attests were Nde to use superconducting materials for However, comparison of the present properties of these materials various applications. Initially, the Interest was (n research with those based on nlobiu* alloys and compounds emphasizes the Instrumentation, In the fora of both large Magnets and devices very significant research, development and engineering efforts for the Measurement of very snail Magnetic fields. With time, that will have to be made to achieve this goal. Session El SQUID Applications 9:45 a.m.-noon, Wednesday, August 24, 1988 t mifitjm.T Mir iM.hii.-s 1h»- •rriit fl'i1- . -.ii| led .UJ-' '< < ti.mt;.-. j n EM ori.-nt; 1-i • • f.-iiti.i .f !••. vhil-t N.IM'V .n,|..,t ,1-1. maghi-t i. 48 EI-6 excess of 13.000. Magnetic field maps indicated that the source of DESIGN, FABRICATION. AND Pf-RrORMANCF OF IN- the magnetic fields could be localized to much better than 1 mm. TEGRATED MINIATl'RE SQUID SUSCf-PTOMFTERS MB X-rays showed the presence of circuit elements in the region of Kctchcn, D.I) Auschalum, W.I (jall-ipticr, AW Klcinsasscr, R 1 the magnetic field maxima. Interpretation of the field sources as SaruKtmm, J.R. Rn/cn, B. Bumble IBM T i W.iKon Research Center. 2 Ynrktown Heights, NY' - Inicpralcil, miniature, thin-film dc SQUID magnetic dipoles yield mz values ranging from 10-* Am to 10-* susccpiomctcr*, first ifcmnnsiralcil in I**S*1]. have niuv been applied in Am-. The implication of this work is that SQUID magnetometers the investigation of ,1 number <•!" irncrcsting physical systems1. The lev- offer the potential use in non-contact detection of timing circuits erage of such Misccplnmclcrs derive* from their ability to measure with and microprocessors. extreme sensitivity the magnetic properties of micrometer size samples at low temperatures. 1 he range of application1, for these devices can he considerably broadened through improved magnetic, optical, and ther- EI-8 mal isolation between the pickup loops and the active SOU ID elements. SPATIAL DECONVOLUTION ALGORITHM FOR SUPER- CONDUCTING PLANAR GRADIOMETER ARRAYS, A.C. Bruno and In this paper we shall discuss techniques for integrating such features P. Costa Ribeiro, Departamento de Fisica, PUC/RJ, into single chip structures, as well as modular designs where SQUID Rio de Janeiro, Brasil - In order to perform biomag- and pickup loops arc on physically separate substrates and connected netic measurements in unshielded environments, SQUID by low inductance wire bonds. Extension of ilm latter technique makes gradiometers have been used to discriminate the weak bioraagnetic source from the environmental noise. possible the incorporation of commercial SOU IIX as well as high Tc Generally, the measurements are taken by displacing superconductors. Experimental results on some of these systems which the sensor over a great number of positions around we have built and operated will be presented the source, which is time consuming and allows chan- ges on the subject conditions from one measurement to another. A great improvement in SQUID and gra- diometer construction has been obtained with thin I. M B Ketchcn, I Knplcy. and H. Ning. Appl. Phys. Lett. 44, 1008 film deposition techniques, allowing fabrication of arrays with a large number of detecting sensors. However, this technique leads to gradiometer planar designs with the drawback of a complex output, ma- ?. See, feu example, D.D Awschalnm. I. War nock, and S vnn Motnar. king the signal interpretation difficult. It is Phys. Rev Lett. 5H. 812 (I9K7) presented an algorithm that recovers the original field from the output measurements. It is based in modeling the planar element of the array as a nonre- cursive spatial filter, permiting the evaluation of EI-7 its spatial transfer function. Having the output measurements and transfer function, the input signal SQUID DETECTION OF ELECTRONIC TIMING can be reconstructed. The algorithm is independent CIRCUITS, R. L. Fagaly, Biomagnelic Technologies, Inc., P. O. of any kind of field source. However, it is strongly dependent on the array configuration. As an example, Box 210079, San Diego. CA 92121 - We report on the use of a the recovery of a dipolar field is done from simu- SQUID magnetometer to detect audiofrequency timing signals lated measurements with arrays of 50 and 100 linear gradiometers. The original field intensities can be from electronic and electromechanical clock circuits. The quality recovered with errors less than 1%, if the array factor (Q) of the electromechanical clock was found to be in density is adjusted according to the source depth. Session ML High Tc Superconductors: Oxygen Ordering 9:45 a.m.-noon, Wednesday, August 24, 1988 preparation of oxide materials with favorable superconducting ML-1 properties. The oxygen partial pressure is measured for different stoichiometries and temperatures in the range between OXIDATION KINETICS IN OXYGEN DEFICIENT 500 and BOO'C. In addition, the kinetics of oxygen loading and degasing are investigated. YBa2Cu3O7 s STUDIED BY NEUTRON POWDER DIFFRACTION. J. Als-Nielsen, N.H. Andersen. C. Broholm. K.N. Clausen. B. Ubech, The results are applied to the in-situ preparation of high- and M. Nielsen, Physics Department, Ris# National Laboratory. Tc oxide superconductors by vapor condensation techniques. Denmark - A high-resolution, multi-detector neutron powder difFractometer has been used Tor on-line studies of the oxidation •Supported by the BMFT, FRG kinetics in ceramic powders of oxygen deficient YB^CU^OT %• The measurements show that oxygen deficient YBa2Cu3O7.K with x •» 1 may be prepared from tetragonal phase material by evacuation. ML-4 Subsequent cooling under vacuum to room temperature maintain the tetragonal phase and the oxygen deficiency. At room temperature the sample is stable in air. Heat treatments in pure oxygen at 165°C for 50 hours are sufficient to transform iippriixiiiKUfly 75% of the sample to orthorhombic YBa^CusO? material. A semi-dynamical step-wise increase of temperature by 25°C every two hours from room temperature to 300"C resulted in a complete transformation. Crystallographic studies of the orthorhombic - tetragonal phase transition in 100% oxygen and in vacuum are performed. Studies of . _ . . _. . .-yist* vity, and magnetic supectlblllty the reaction kinetics in preparation of YBa2CusO7 from powder HB.i Cu 'J corpoun'Js < H= Y .Ud ) were Investigated for oxy- mixtures of Y2O3, BaCO3, and CuO are also presented. tf'.-ri ; >ri?T.t b <. x < 7. Oxygen atoms and vacarisles disordering in Uas'ii plane (Between 01 rind Ob sites) appears to occur mainly ;iL iuw tempi.*fdture range ! up to '.OO-'jOO C) wltnout null .,TiMr ^xyfifjn losses. Di.sordisrJns does not affect T and ML-2 <1H /dl values. There HT? significant oxygen lasses and THEORY OF THE KINETICS OF OXYGEN DIFFUSION, ORDERING, •.rystfii structure changes above t-OO°C. It was obser/ecJ thf AND ANEUSTIC RELAXATION IS rB«2c"3°7±x»+ D* °* Welch,* H. A. Bikker,** J. P. A. Weaterveld,** and D. M. R. C-axir. Inl^i-atomlc dlstanc-^i fia-Y|Cd> and C^-Cul become shor- Lo Caaclo,*• *Brookhaven National Labors tory and ••The Onlver- ter while 5a-fia and 0^-Cu? become longer. These structure sx ty o* AIAStcrdafli ~ Tne superconducting properties of 1^2^3 structure oxides depend critically on the oxygen content and decree or order, and orope r processing tntj t nod 3 Are ^overned oy Ktfnrcetry lattice fatjout BSOU in air). methods have been used to study oxygen kinetics by various research groups, among then tracer diffusion, oxygen uptake ML-5 and release kinetics* and anel&stic relaxjitlon. In this paper ue present a theoretical analysis of these processes and dis- OXYCEH STOICHIOMETRY ORDERING AND SUPERCONDUCTIVITY IN cuss the reasons for the observed differences In activation Y.SajCujO,.*, Y.Hariharan,V.S.Sastry,M.P. Janawadkar,J.Jaruki, energies. 0 M Sreedharan, R.Pankajavalli, and T.S.Radhakrishxun, Indira Gandhi Centre for Atoalc Research, Kalpaitku, India-Oxygen deficient Y, B*a_ Cuj 0>-x (YflCO) saapleB were prepared by U.S. Department of Energy under Contract Mo. DE-AC02- quenching the« Into LN^afcer heat treatment la the temperature 76CH00016 and by the Dutch Foundation for Fundamental range 950-200°C in air and flowing oxygen and by low Research on Hatter (FOH). temperature annealing (300-550°C) In either argon atmoiphere or vacuum, Theie treatments yield samples with varying oxygen concentrations and with different degrees of order. The oxygen stoichiometrles evaluated using techniques like weight change, ML-3 lodometry and IGA are compared. It is found that the DET£RM"1ATION OF OXYGEN PARTIAL PRESSURE FOR HIGH-Tc stoichlometry is the same whether the quenching Is done after OXIDE SUPERCONDUCTORS,* R. Bormann, Institut fur Meiallphysik, annealing In air or flowing oxygen. Identical starting samples given identical heat treatments have higher resistivity values and broader superconducting transitions (measured by a.c susceptibility technique] when annealing for a specified time ermodynamji 1B done In air environment. The value of x at which the 60 K 49 plateau In 1^ occurs depends on Che partial pressure of oxygen Jt(t,n) • OC(Q,OJ • enp(-t/t0) • exp(-x/x0) with t0 ~O.ll and la which annealing la done. However a unique correlation x0 = 0.033. This approximate universal behavior suggests that independent of thia oxygen partial pressure emerges between the neither the orthorhombic distortion nor twinning are essential realstlvlty and Tc as a result- of these measurements. Detailed limiting factors in the intrinsic critical current behavior In analyaia of X-Ray powder diffraction lines reveal systematic the Y-123 class of superconductors. These and other results variation* of Intensity and haIfwidth of certain lines as a on the magnetic properties wi11 be discussed. lunctloo of oxyften scolcnlovetry• FITOH these results It X-S inferred that the superconductivity in YBCO depends not only on •Operated by Martin Marietta Energy Systems, Inc. under con- oxygen stolchloaetry but also on the nature of its ordering in tract OE-AC05-840R21400 for the U.S. Department of Eneryy. the basal plane of the unit cell of this compound- ML-7 ML-6 .,1 Mia ICu I.) O. SUPERCONDUCTIVITY, CRITICAL CURRENT DENSITY, AND MAG' B U!h HETIC PROPERTIES OF Fe-SUBSTITUTED Y^tCu i.xFeK) Pz MATE- K Hfinrma] RIALS, S. T. Sekula, J. Brynestad, D. K. Christen, J. R. Thompson, and Y. Kim, Solid State Division, Oak Ridge National tli*"tinv*- "liinuiianstr -1. D ~ 3 I Go Laboratory,* Oak Ridge, TN -- He have Investigated a series of Fe-subst1tuted superconducting YiBa2(Cui_xFex)302 polycrystal- Hne materials for 0 < * < 0.10 in order to ascertain the ni,-:h»l Thi- critical current rf.- Jr uni' dciormia-i l>> 4 ;.rob«; Influence of the degree of orthorhombicity on the transition te*per«ture Tc and the critical current density Jc. The densities of the sintered samples were > 90% of the theoreti- cal value, kith Increasing Fe content x, the orthorhonbtc distortion decreased, resulting In essentially tetragonal 'materials for x > 0,03 as revealed by X-ray diffraction. Hetallographic studies showed that the twinning structure diminished concurrently. Tc decreased smoothly as a function of x with the Keissner flux expulsion In an applied field of 10 Oe retaining nearly constant at 40-^*5*. Similar results were obtained for separately prepared batches of Fe-doped Y-123 powder. Measurements of the magnetization were carried out In the temperature Interval from 4.2 K to Tc for each sample in Mgnetic fields up to 78 kOe. J , as determined c • of t«inniii(; in rhi- r from the hysteresis In the magnetization process, varied expo- nentially with reduced temperature t-(T/Tc) and x. He find Session LI Stability II 9:45 a.m.-noon, Wednesday, August 24, 1988 acbiived. The MPZ concept is shown to be a powerful tool and LI-1 it has had a Mjor iapact on the design parameters and SOME ASPECTS OF MODERN THEORY OF APPLIED SUPERCON- operating sodas of these coils. DUCTIVITY, * iVN.Martovctsky, Kurchatov Institute: of Atomic Energy, Moscow, USSR - Insight into applied superconductivity based on Bean model of critical state concerning processes which take place in the SC wires makes it possible to develop scries of important recommendations for sitperconduclon. LI-4 advance. In »pitc of the progress there are many principal facts from experi- qUENCH ANALYSIS OF FORCED-FLOW-COOLED CABLE-IN-COHDUIT ments and practice which can not be explained in framework, of this understan- SUPERCONDUCTORS,* J. A. Kerns, R. L. Kong, and J. R. Miller, ding especially for nonstabilizcd conductors with high currents. This contra- Lawrence Ltvermore National Laboratory — Protection of dictions originate from the fact lhai a transition characteristic of the supercon- superconducting magnets made with forced-flow cable-1n-condu1t ductor is smoothed in a region of electrical fields where modern superconduc- conductors (CICC) depends on the maximum hot-spot conductor tors work. This situation required lo revise many aspects of theory and prac- temperature and the maximum Internal helium pressure that can tice of applied superconductivity: I) methods of measuring and describing of be tolerated during a quench. We have developed a computer characteristics of superconductors; 2) electrodynamics of superconductors • code that simulates the growth of a non-recoverable zone and penetration of magnetic flux, dissiputivc characteristics; 3) theory of stability, predicts conductor temperature and the state of helium results of which especially strongly differs from classical ones; 4) representa- throughout the CICC during quench and dump. The calculation tion! of relations between structure and inhomo^eiiiiy of superconductors and uses variable conductor, helium, and conduit material shape of transition characteristics. A review of main results which have been properties. The analysis has been checked against existing obtained in these fields is presented. A possibility of stable performance of SC experimental data and other numerical calculations. This composite* with high currents and poor cooling at varions types of disturban- numerical model has been used to study normal zone growth and ces is shown. quench scenarios 1n a version of the International Thermonuclear Experimental Reactor (ITER) toroidal filed 50 s&iisfy two sets of criteria. During normal operation, sufficient stabiliser the stored energy, temperature rise, and coil geometry which are useful in must be provided to either make the coil unconditionally stable or to give •coping the required amount of stabilizer. Com pan son with some recently a certain desired stability margin. Once a dump occurs, the nmuunt of proponed fusion magnet tystem designs indicates that excessive dump stabilizer must be large enough to carry the current without generating voltages will result in some cases. High-temperature superconductors excessive dump voltages or allowing the winding to exceed a certain may require more stabilizer than the conventional alloys. Calculations maximum temperature. The second criterion often dominates for very with simple model coil systems indicate how tradeoffs between various large coil systems, but is frequently ignored in initial design studies. coil parameters nffccl the dump voltage and overall coil costs. This paper gives some simple relations between the dump voltage and Session EJ 3 Terminal Devices/IC Processing II 9:45 a.m.-noon, Wednesday, August 24, 1988 EJ-1 function of barrier deposition conditions. SUBMICRON NbN JOSEPHSON TUNNEL JUNCTIONS FOR DIGITAL APPLICATIONS, M. Aoyagi. A. Shoji, S. Kosaka, H. EJ-5 Nakagawa, and S. Takada, Electrotechnical Laboratory -- NbN EDGE JUNCTION FABRICATION: ciXiE PROFILE Submicron NbN/MgO/NbN Josephson tunnel junctions were CONTROL BY REACTIVE ION ETCHING* X.F. Meng. R.S. Amos. A.W. Lichtenbercer. RJ. Miniuch, and MJ. Feldnun. Deputmeni of Electrical fabricated using a new process, in which the cross-line- Engineering. University of Virginia -- [n order to fabricate NbN edge patterning (CLIP) method and the electron-beam (EB) junctions with low parasitic capacitance, an insulator with low dielectric lithography technique were introduced. The junctions had constant, such as S1O2, must isolate the base and counter-electrode except on the edge. We use reactive ion etching to cut an edge in SiOj/NbN bilayer low subgap leakage current (Vm-20mV at 2mV) and low lc- films. For this process it is necessary that S1O2 be etched more rapidly than spread (0-9.6% for 0.75|im-square NbN/MgO/NbN junctions). NbN to form a suitably sloped edge profile. We have investigated the A 4JL-0R gate which contains 0.Slim-square NbN/MgO/NbN influence of etching gas composition and other parameters on etching rales and edge profiles, using: 1)CF4. 2) CF|.l raV]^ ELECTRICAL CHARACTERISTICS OF NbCN/PbBi EDGE JUNCTIONS.* small subgap Leakage current (V r 50 mV) for J y 10 A.cm A.W. Lictitenbercer. MJ. Feldmtn, ind RJ. Mattiuch, Department of at 4.2 K. MgO barriers which sRow nearly symefrical shapes Electrical Engineering, University of Virginia -- We hive attempted to and sustain relatively high electric&1 fields before breaking fabricate NbN edge junctions using i technique which is commonly employed car. be obtained either with large effective barrier heights to make Nb edge junctions. A modified commercial ion gun was used to cut iiv2.B eVI close- to theory or with much higher transparences in edge in SiO^bCN films partially covered with photoresist An insulating depending on the preparation conditions and oxygen content in MgO . It is deduced that resonant tunneling states which are barrier was then formed on the exposed edge by reactive ion beam oxidation, observed in non stoechioraetnc MgO can be suppressed in a and a counterelectrode of PbBi was deposited. The electrical quality of the controlable way by junction postannealing around 270"C, by resulting junctions was found 10 be strongly influenced by the ion beam MgO in situ oxidation before counterelectrode deposition or acceleration voltages used lo cut the edge and to oxidize it. For low ion beam by MgO deposition in a reactive gas mixture. Possible voltages, the junction quality parameter was as good as Vm*55 mV appLications of such MgO barriers with high T oxide super- (measured at 3 mV), but higher ion beam voltages yielded strikingly poorer conductors will be also presented. quality junctions. In light of the small coherence length of NbN (% < 4 nm}, the dependence of the electrical characteristics on ion beam voltage is presumably due to mechanical damage of the NbCN surface. In contrast, for EJ-3 similar ion beam voltages, no such dependence was found for Nb (^ > 10 nm) PROPERTIES OF STACKED NBN-TUNNELJUNCTIONS. H.-J. Hed- edge junctions. babny* and h*. Rogalla, Univeraiteit Twente, *Universltat Gie&en - We prepared aultiple layers of HbN with MgO-barriers •Supported in part by grants AFOSR #36-0056 and NASA #NAS5-26466. in between by two different Kthods. In the first one the whole stack was prepared in-sltu and structured afterwards by EJ-7 lift-off technique and reactive and argon Ion etching. We FABRICATION OF Nb/Al-AljOj/Nb JUNCTIONS WITH investigated the IV-characteristic* of a stack consisting of EXTREMELY LOW LEAKAGE CURRENTS,* A.W. Uchienberger. two NbK-tunneljunctions. Susgap voltages of 8.5 «V were C.P. McClay, RJ. Mittauch. and MJ. Feldman, Department of Electrical observed. Because it is difficult to establish an electrical Engineering, University of Virginia; S.-K. Pan and A.R. Kctr. NRAOt » A connection to the Middle electrode a second aethod was five level mask set is used to fabricate Josephson tunnel junctions from applied. Each KbN-and KgO-layer is prepared in a seperate Nb/AI-Al3OyNb trilayer films. The trilayer films are deposited using DC 1 step. In this case we aainly investigated the interaction magnetron sputtering guns, in a UHV system which is capable of SxlO" " Torr between the two tunneljunctions, especially **ie rf-propertles and has a water-cooled routable substrate platter. A hybrid RIE and wet etch of these junctions. Microwave-Induced steps in the IV- is used initially to pattern the trilayer to linewidths as small as 1 tun. The junction areas are defined by RIE and their edges are seated with either Nb^j characCeristics of one junction were observed, while the or SiO2. A Nb wiring level is defined by an image reversal photoresist liftoff second Junction, biased at an appropriate voltage, acts as process which also gives linewidths as small as 1 fun. The wiring level •icrowave generator. includes two different types of inductive tuning structures which arc designed to resonate the junction capacitance at 110 or at 220 GHz. The remarkably low leakage currents of these junctions - the sub-gap current (at 90% of the EJ-4 sum-gap voltage) is as small as 0.3% of the quasiparticle current rise at the 2 NbN BASED JOSEPHSON JUNCTION WITH SILICON BARRIER sum-gap voltage (jc = 750 A/cm ), at 2.0 K -- will be compared lo the predictions of the BC5 theory. Measurements of the specific capacitance will Research Laboratory - Low resistivity niobLua nitride thin be presented- temperatures greater than 700°C. These naterials have a resistivity approximately BO uO-cm and a sagnetic penetration •Supported in part by NSFgrant#AST-65122M. depth less than 200 nm. These aaterial properties may be of tThe National Radio Astronomy•• Observatory is operated by Associated importance In the design of alll'seter wave SIS nixers and Universities, Inc., under contract with the NSF. associated circuitry. Current barrier technology is not compatible with these high substrate temperatures. We have been investigating the properties of KbN/Sl/Nb tunnel junctions with silicon barriers sputttered at substrate tenperatures to EJ-8 700°C« These junctions have a figure of *erlt VB greater than SUPERCURRENT NONUNIFORMITIES IN JOSEPHSON TUNNEL 20 mV and a sumgap Vg which decreases with increasing substrate JUNCTIONS INDUCED BY NITROGEN ION IMPLANTATION, • C. temperature. Analysis of the high voltage current - voltage Carrier lingo and H. Busso, CNR - Istituto di characteristics using the Simmons nodel for the average barrier Cibernetica, Arco Felice (Naples), Italy - Nitrogen height show an abrupt Increase in barrier height from 35 to 95 ion implantation has been used to induce local neV at about a 400eC substrate temperature. These and other modifications of the superconductive properties, of 51 the niobium baae-layer in Nb-NbOK-Pb Josephson tunnel kinetic inductance of the Josephson line, as well as by junctions. A local depression of the niobium crit ical reducing a width W of the line. The kinetic inductance can be temperature, and energy gap, turns into a nonuniform increased by thinning the thickness t of an elei.trode of the line, and by using the electrode with large London pcneirutlun critical current density profile Jc(x,y) in the depth such as NbfJ. The ohtained transresistance is as large sample. A large variety of Jc different shapes Have as r -I Ml for t-60nm and W=-4um. For this value of r . the been obtained by modifying the implanted region curren! nain of the amplifier is estimated to be 200. It geometry and the nitrogen ion concent rat ion. The will be possible to increase r up to r -10ft in the case wlieu external magnetic field dependence of the maximum dc t">15nm ,-uid WsJum. It is »lso shown that the linear operation Josephson current has been used as a diagnostic tool, range of the amplifier is as large as UV. Based on ihv to get a preliminary characterization of the shape of experimental results, performances of the amplifier are compared with those of the SQUID amplifier. Jc in "small" (L,W < X^) samples. In particular, results concerning junctions exhibit ing a "regular" nonuniform critical current density profile Jc - Jc (xt, are discussed. Results on the occurrence of EJ-13 self-resonant modes and preliminary investigations on EXPERIMENT OF FIELD-EFFECT TRANSISTOR W/TH A CHANNEL "long" junct ions (L > X j) are also reported, The MADE OF UBN GRANULAR THIN FILM, M.Sugahara, N.Voshikawa and capability of controlling the spatial dependence of T.Murakami, Yokohama National University - An experimental study is made on a three-terminal device which has a structure the critical current density distribution, in a of a field-effect transistor with a channel made of a NbH Josephson tunnel junction, is discussed in the granular thin film. The specimen is equipped with a source and framework of possible applications. a drain electrodes of Nb, a gate insulator made of SiO and a gate electrode of Al. The granular thin film for the channel •Supported in part by EEC under the contract ST2J- has mean thickness of about 3nm, which was deposited on a glass ,0267-C substrate with reactive rf sputtering. The NbN granular thin film used in the experiment has high room-temperature sheet resistance (larger than the critical resistance R»=6.45tel and EJ-9 shows a insulating transition at low temperature. The IV characteristic of the channel nas strong nonlinearity at low mjassDC OF TKKX FUM DUMCTRICS ccwwrrsu: wrm iron temperature. When a voltage is applied to the gate electrode, FIIH SUPQCCKUCrCIS KR AKMCG SIO&L fHXZSSIXG CEVICXS,* the channel resistance shows a variation with sinusoidal cjate S. C. Hong, A. c. Andatvcn, X^ncoln Laboratory, .1*1—in Itiaiil l» voltage dependence- One period of the resistance variation Bwtitut* of Technology, and D. A. Altai, Ifcao lull Is takes place for the gate voltage interval -. 1 30V, w.iJ.ch Imtitute of Technology, D»tailMit of Mitarials Sciance arri corresponds to the induction of electric pair charge 2e on a Erginaarinj - We have bamnatntad the faaaibility of grain of the channel. The sinusoidal resistance variation integrating thick-film dlelectrio vith thin-til» appears at temperature below \ 10K and is enhanced with iyemjiJuctor» in th* fabrication of sional procaaaing deviaaa. temperature decrease. The maximum resistance variation observed Thin fill* of ft> and KH arc dapoaitad by rf aputtaring and at 4.2K is 12%. Supposing that the granular thin film is the pattamad photolithographicaUy. Thick fil» dialactricz can ba two dimensional array of small superconductor tunnel ing 9pun-cn to a controllad thicknaaa of 10 to 25 aicronc, uhich is junctions, this field effect can be attributed to the new an optiaua range for high-oanaity, lcw-loaa •icroueve delay quantum effect dual to the Josephson effect, which we call POT lines. After an organic binder burnout step at 450% in air, effect. the oaraaic dielectrics are sintered onto the MM thin filx* at 850% in vacua. The transition taeperature of the *H changes froa 15 K as sputtered to 9 K after sintering, but euperocnfcictivity is preserved by the presence of thln-f il» HgO and SiOj barrier layers. Iiapad-elaamc resonators, in which EJ-14 the inductor and the capacitor electrodes are Bade of MAI and PROSPECTS FOR PROXIMITY EFFECT SUPERCON- the dielectric of thick film ceramic, have bean successfully DUCTING FETS,' A.W. Klcinsasser and T.N. Jackson, IBM Re- fabricated for Measuring the dielectric properties of the search Division, Yarltlown Heights, NY - Proximity effect ceramics at 4.2 K and 10 mi. Preliminary result* indicate a dielectric constant of 6-6 and tan of 10~2. superconducting field effect transistors (FETs) were first discussed over a decade ago, and some promising initial experimental results have been *This uork is supported by the DaparbHnts of the Air force and obtained. However neither experiments nor simulations performed to Navy. date have addressed the question of whether or not a useful device is feasible. In this paper we investigate potential performance of these devices, discussing device characteristics and the circuit implications of EJ-10 such properties as zero on-state resistance. We emphasize three aspects: EXPERIMENTAL RESULTS ON A MULTI-ELEMENT VORTEX FLOW (1) The natural voltage scales for Held effect control of semiconductors TRANSISTOR AMPLIFIER,* D. P. McGlnnis, M. A. Ketkar. J, 9. and for Joscphson weak links arc incompatible. The extent to which this Beyer, and J, E. Nordman. University of Wisconsin-Madison - A can be overcome by maximizing gate capacitance and weak link critical Niobium based superconducting amplifier consisting of a series array of 60 Vortex Flow Transistors (VFT) was fabricated and current-resistance product, allowing a device exhibiting voltage gain to tested. Each VFT consisted of a long Josephson junction biased be fabricated, will be examined. (2) Device length and operating tem- in the flux flow state magnetically coupled to a current perature arc constrained by the natural length !.cale for the penetration carrying control ?1ne. The topology of the amplifier is based of superconductivity into normal materials, so that submicrometer de- on a distributed amp!If 1 er configuration. The gain of the vice dimensions are required and silicon is effectively ruled out in favor amplifier corresponded to a net dc transresistance between .5 to 1.5 ohms. of III-V materials for any devices operating above -20 K. (3) We dis- cuss the implications of (1) and (2) for the use of high temperature *The work was supported under the Air Force Office of superconductors as source and drain contacts in FETs. Scientific Research Grant No. AFOSR-86-0025 'Partial support for this work was provided by the Office of Naval Re- EJ-11 search under contract NO00I4-85-C-0361. A MODIFIED SUPERCONDUCTING CURRENT INJECTION TRANSISTOR AND DISTRIBUTED AMPLIFIER DESIGN,* 0. P. McGinnis, J. B. Beyer, J- E. Nordman, University of Wisconsin-Madison - He have EJ-15 developed the design and theory of operation of a Modified NOISE MODEL FOR THE SUPERCONDUCTING-BASE superconducting Current Injection Transistor (MOD-CIT). The SEMICONDUCTOR-ISOLATED TRANSISTOR A. D«vidson and MOO-CIT consists of a resistively damped long junction in which the maximum Josephson current is modulated with the magnetic DJ. Frank, IBM Research Division. Yorklown Heights, NY - The suc- field produced by current in a dc decoupled control line. The cessful development of the Superconducting-Bate Semiconducior- junction is asymmetrically biased so that the maximum current Isolated Transistor (SUBSTT) could result in a device with noise gain is achieved. The maximum frequency of operation of this approaching the quantum limit. The SUBSIT is one of a class of devices device is limited by the transit time of a fluxon through the that could potentially be developed from contacts between supercon- junction. Transit time cutoff frequencies can be as high as ductors and semiconductors. The SUBSIT would work in analogy with several hundred gigahertz. Also presented 1s a unique distri- buted amplifier design for the MOD-CIT that is a hybrid of the tht mechanism of ordinary bipolar transistors, except with the use of Field Effect Transistor and the Superconducting Vortex Flow quasiparticles and Cooper pairs, instead of electrons and holes. We Transistor distributed amplifier configurations. The distribu- expect the bipolar analogy to hold for analysis of noise, and so apply a ted amplifier design for the MOD-CIT demonstrates that at least fairly standard bipolar noise model. We put one noise source in the 10 dB of gain can be delivered into a 2 ohm load for frequen- emitter circuit, to represent shot noise due to the emitter bias current, cies up to 100 GHz with only four devices in the amplifier, and a second noise source in the collector, representing the shot noise due to leakage from the base to collector. We assume this leakage can *The work was supported under the Air Force Office of be kept small compared to ihe bias, as in semiconductor bipolars. If the Scientific Research Grant No. AFOSR-86-0025. emitter electrode is a normal metal, then we get the usual bipolar noise temperature. However, if the emitter is made superconducting, as well as the base, we show that the sharper emitter-base current-voltage EJ-12 characteristic causes a drastic reduction in noise. We expect the PERFORMANCES OF A FLUX-FLOW-TYPE JOSEPHSON AMPLIFIER, equivalent noise sources referred to the input to be in the picovolt and K. Enpuku, T. Hashimoto and K. Yoshida, Dept. of Electronics. picoamp per root Hz range, with an energy resolution comparable to Kyushu University 36, Fukuoka 812, Japan We have been Planck's constant. developing an analog amplifier utilizing a flux flow phe- nomenon in a Josephson line, i.e., Flux Flov Amplifier(FFA). The amplifier is characterized by a large current gain and a wide linear operation range. Experimental studies have been EJ-16 nade to inprove performances of the amplifier, such as a CAP MEASUREMENT IN Nb/NbOx/Al INJECTION CONTROLLED transresistance r , a current gain and a linear operation PLANAR THREE TERMINAL DEVICES, 8. Takeuchi and 1. Okabe, range. Here, thentransresistance is a conversion efficiency between a signal current I and an output voltage V of the University of Tokyo - In order to directly measure gap V amplifier, i.e., r - /IB- It is shown that the transre- suppression in injection controlled superconducting links, sistance can be improved significantly by utilizing the we hBve fabricated Nb/SbO^/Al croSB-llne devices mth a 52 Nb/A10x/Nb tunnel Junction (detector Junction) attached to was usec to calculate tne device parameters in case the active region. The critical current (I ) of a Nb strip c ci1 invercion and accumulation channels. The exjjeriffient ta suppressed by current injection fron the Al atrip di. vices were d*Ginned and main tec:ir.oio6ic«il problems crossing upon it. At the same tine, it wsa found that the *er; inve^ti^^ted. Theoretical and experimental results were com^arec in ca~e oi accumulation cnai.nel gap In the Nb line also decreases. Measured injection power ami (IOOQ agreement was i'ountw (P^), Ic and SUB gap voltage ( Ai+ 1*2) have been coapared with the predictions of T* model and staple heating model, and the relation between P^ and Ic can be well fitted to EJ-19 the latter aodel. However, the decrease of &1+&2 for large P^ is Boaewhat eaaller than the theoretical value, HEW P0SSIBIL1TIC5 FOR SUPERCONDUCTOR LLLCTRO- MICS, K. K. Likharev, V. K. Semenov, and A. B. Zorln, presumably due to spreading of nonequilibrlua particles Huscow State University - - Recent discovery of the into the detector electrode. high Tc superconductivity of the copper oxides and Junction devices hdvc crre^ited orlont jjrosjjccts for EJ-17 superconductor electronics. Ihe purpose of the present report *i 11 be to revle* those developments Session MM High Tc Superconductors: Miscellaneous Properties 9:45 a.m.-noon, Wednesday, August 24, 1988 MM-1 MM-3 F1UX OCMPRESSICW IN KTffl TWIRWURE affERCDKrjUCTORS, * A SUPHtCOHDOCTIVE SHIELDIHC CAN FOR HIGH Tc SQUID. Guancji Oil. U. E. Israelsson, D. M. Stxayer, and H. w. Jackson, Jet Prcpulsicn Laboratory, California Institute of Technology - Shiguang HANG, Jiazhanc LI, Huaiinc JIANG, and Chuanyi LI. Pekinc Magnetization naasurenents in sintered Efe^YCUjO? ^re carried University, Caidong LIN. The Central South China University, out using a flux cotpraasion Method. In the present experimental set i*p iiagnetic fields as hicfi as 5.5 T can be P.R. China, - For operating a high Tc SQUID at temerature range applied to the 2.5 an diowetar sapplaa. The compression cavity of 30-80 K, a ne» kind of superconductive shielding is needed. is 1 en in diameter, and a maxima coBpreesion of 3 is Ve have fabricated and investigated a superconductive shielding available. The actual value of the conpressed magnetic field is determined by the applied field, the tenperature, and by can for our nigh Tc SQUID sensors. The cm vas Bade of YBaCuO properties of the superconducting sanple. Sane technological ceraaic mterials »ith a nail thickness of 3 m. length 115 m applications of the flux oonpression technique will be end inner diaieter 16 m. Single phase VBaCluO? sized 4-5Hi vss discussed. prepared by the conventional Kthod. The can's body ns forged by • Research supported by the National Aeronautics and Space isostatic pressing and folloved by high teaperature annealing. Administration. The highest shielding ability to the external aagnetic field is 16.6 Oe. The characterization of the superconductive Mgnetic MM-2 shielding in SQUID systea is reported. APPLICABILITY OF OXIDE SUPERCONDUCTOR TO MAGNETIC SHIELDING,* T.Okada, K.Takahata and S.Nlshijima, ISIR Osaka MM-4 University, Ibarakl, Osaka 567 — Magnetic shielding D.C. CRITICAL CURRENTS IN St'PERCONDUCTING CERAMIC SAMPLES OF V,Ba,Cu_O , C. Pjternd, C. Alvani*. S. Casadlo*. U. Gambar- superconduc£QT*> CT*iticAl current oensity 3nd niasnctlzotion della,'L.Maritato , Associazlone EL'RATOM-ESEA sulla Fualone, were measured using the four-terminal and electromagnetic CentTO Rlcerclie Energia Frascati, C.P. 65, 00044 Frascati, methods at the temperature of 77 K, The results indicated Rome, Italy - Critical currents carried by ceramic Y-Ba^Cti.O. that the critical current density was decreased significantly superconductorB have been measured, at different temperatures. with increasing the magnet ic fleld. On the other hand, the The measurements have been performed on samples of suitable -jh.ipe by a four prnbe contacts method by detecting the voltage C he iLcssu i*cd critical current densicy> Hddy current H we re found to flow not bulkily but in small circuits. The magnetic using Hall sensor. The shielding efficiency was appeared up to 1 Testa even if eddy currents flow in small circuits. The rurri-nt direction, have been investigated. A strong dependence applicarfilicv or oxide superconductor to hlch tnacnetic of the maximum critical current on the applied field is obser- shielding is discussed. ved. The behaviour IK discussed In terms of Jntergrain weak 53 coupling. A comparison between theoretical and experimental data for the temperature dependence of the uxlmra critical MM-9 current Is alto reported. HALL EFFECT AND HALL RESISTIVITY IN REBa3Cuj07 • H. Thiex and K. ttinzer, I. Physikalisches Institut, University • EWEA, CKE CasacCla, ROM, Italy of Gottingen, FRG IrTFN, 00044 Traecntl, Home, Italy Results of Hall effect and Hall resistivity for single phase REBfljCujOT (RE « V, Sen, Tra and Vb) around and above Tc are re- ported. For all samples the Hall numbers Vo/BHe show a linear MM-5 temperature dependence in the range 120 K < T < 300 K. The tem- perature dependences of p(T) and R IT) were used to analyse V0LTAG2-CUMEHT CHARACTERISTICS OP BULK YBl Cu O SUPER- H carrier concentrations and mobilities in terms of a simple two- CONDUCTORS, YU Dingan, TANG junping and ZHANG Dunfiou, General band model. Research Inatitute for Non-Perrous Hetals, Beijing, p.R. of China - v-I characteristica.of sintered, bulk YBa.Cu.O samples In the temperature range between 85 K and 95 K a non linear be- vith Jc ranging from 30 to 10V«» wer« Measured ifi zirS applied haviour of the Hall resistivity pXy with a change of sign is Magnetic fields and at liquid nitrogen temperatures by using a observed on samples with HE = Y. Sm as a function of the magne- Microcomputer-controlled ic Measuring system. The results show tic field. The strong field dependence of pxv near Tc can be that the V-I characteristics of these superconducting oxides can attributed to the effect of grain boundaries, which can domi- be divided into four stages. In the first stage where voltage nate the Hall resistivity by their low carrier concentration. starts to 90 upwards, the voltage can be expressed as an The amount of the "anomalous" Hall resistivity strongly depends exponential function of the current, i.e. V- Vo exp(nl), which is on the sample preparation technique. In general samples pre- pared by the citrate synthesis show smaller pxy-anomalies, traditional superconductora nuch »M NbTi alloys. Horeover, n smaller Hall numbers and higher critical densities of current increases with trie sample's Jc. In the second stage, the voltage compared to samples prepared by the usual solid state reaction. is a linear function of the current but its slope (dV/dI> is Much lets than the normal state resistance of the sample. Finally, a • Supported in part by the Federal Ministry for Research and unstable stage characterized by a sharply rising voltage appears Technology (BHFT) before the v—] characteriat ic is turned into a norinal state one* The •Jtperimental results have been analyzed and discussed. MM-10 CHARACTERIZING THE CURRENT CARRYING CAPACITY OF MM-6 DIFFERENT HIGH Tc SUPERCONDUCTORS WITH AS MUCH SENSITIVITY AS SUPERCONDUCTIVITY AMD CRYSTAL STRUCTURE OF HIGH T, VERSATILITY, P. Metra, L. Gherardi, Societa Cavi Pirelli; Ei-Ca-Sr-Cu-0 COMPOUNDS, V. K. Pan, V. P. Oovgopol, A. G. Vo- R.Mele, CNR-ITM - To quicVly qualify new or optimised versions pov, V. B. Spivakovsky, V. S. Flis, A. V. Zhalko-TUarenko, V. of high Tc ceramic superconductors, not available in the shape G. Bar'yakhtar. Institute of Metal Physics, V. S. H?Jnik-jv, N. of a wire, two simple and accurate methods have been set up. The P. Pshe.ntsova, D. P- Demenko, Institute of Geochemistry and Mineral Pftysics, Kiev, USSR - Superconducting properties, pha- density of small sintered specimens or films with no electrical washer of superconducting material Is fitted as a shorted one supercond'-tcting transitions with HO K T onset were observ- turn secondary winding. The current Is Induced in the specimen ed. Scanning electron microscopic and rnlcroprobe studies reve- by exciting the primary coil with a.c,. and the resulting aLed nonsingle phase composition of the samples. The dominant magnetic flux is very accurately measured with a pick-up coll phase composition might be formulated as Si,SrCaCu_ 0 and a lock-in amplifier. A similar equipment, but In which a where x = 0.*. - 1.0 depends upon heat treatment'procedure. small superconducting disc is Introduced to replace an air gap in the magnetic circuit, is used to measure the a.c. This phase sug^ested to be respons 1 t>le for* the sarnple super— nd conrJucLivity. Its crystal structure was determined by X-ray susceptibility components X' * X" . This method allows to powder diffraction and electron single crystal nlcrodiffrac- study the effect of both temperature and magnetic field (up to tlon as a layered perousk! te-Iike pseucJotetrngonal one with 30 0e) by clearly discriminating between intra™ and inter—^raln conduction transitions. Many results of measurements on either small orthoromblc distortion. A 5-fold superstructure was YBs.Cu.O , and Bismuth compounds are presented. found along b-axe. Crystal appeared to be highly twinned along given by a simple average of the local critical current density «-J !ii f\n «rt - j - ' * , »... * Al ai . . ^^ ~M _ « * 90 1 . * ^ in each grain, i.e.. an expected value of the intragrain current density. Hence, the transport critical current density is ex- pected to be increased up to the intragrain current density by inproving a quality of Materials. However, this value is still The superconducting transition of the weak links is more sensitive much smaller than the critical current density in ordinary high- against irradiation damage than Tc of the grains. The difference field superconductors at the liquid helium temperature. This is between Tc and the phase locking temperature Tcj increases with caused by bad efficiency in flux pinning due to misorientation fiuence. This is in agreement with the more severe influence of the of highly anisotropic twinning planes with large concentration. downset x' (T, B = 0 T) = - 0.9 of the transition which is determined If a fine grain structure of about 0.1 un or an oriented struc- by the weak links. The intergrain (or transport) jc decreases from ture of twinning planes is realized, the transport critical 320 A/cm2 at 10 K, 0 T, +t = 0 to 10 A/cm2 at +t = 1019 cm* showing current density will reach the present level of commercial Nb-Ti. at the ume time an increasing specific resistivity. This is in contrast Experimental results are compared with the theoretical result. to the intragrain jc which shows *n increase by more than one order of magnitude in the fluence region between 2-10'7 cm-2 and 5-10'S cm-2 due to radiation induced pinning centers. MM-8 ESTIMATION OP STABILITY AND CRITICAL CURRENT DENSITY OF MM-12 OXIDE SUPERCONDUCTING WIRES,* S.Nlshljima, K.Takahata, T.Okada, Y.S«Ju.i+, K.lkisava++, T.Morl+, K.lkeda+++, K.UeminamI+++, ISIR SUBSTITUTION OF Hn FOR Cu IN THE HIGH Tc SUPERCONDUCTOR Osska University, Ibarakl, Osaka 567, +Tsu Labs. NKK, Tau, Mie YBa Cu 0 *, R. F. Jardim, 0. F. de Lima, S. Gama. and I. 514-03, ++Tsurumi Kcstarch Labs. NKK, Yokohama, Katiagawa 230, 2 3 7 +++YHP, Yodogatfaku, Osaka The critical current density of Torriani, Inatituto de Fisica - UNICAHP, 13081 Campinas, SP, oxid* superconductor haa been measured changing the temperature Brazil - Samples of YBa (Cu, Hn ) ° . with x - 0.0, 0.01, in order to estimate the magnetic stability against the flux 2 3 7 0.025, 0.0S, 0.075, 0.10, 0.15, and 0.20, were prepared by the both the terminal and magnetization method were used. The thermal conductivity and specific heat were also measured. solid diffusion method. Superconductivity vith Tc in the range The critical current density derived from the magnetization of 84 K to 92 K was observed through resistivity and magnetic iras larger approximately two order of magnitude than that from 4-terminal method. The criterion of the magnetic stability susceptibility measurements. The substitution of Kn {or Cu depends on the critical current density and hence the criterion practically did not affect the transition onset temperature, can not be determined because Che tvo types of critical current density are derived. Experiments were also carried out to although A strong correlation between the transition width observed the flux jumps changing the temperature and current. broadening and the increase of Mn content was observed. This is The appropriate critical current density In estimating the stability of oxide superconductors are discussed. The consistent with the reduction of the superconducting volume problems in obtaining the critical current density is also fraction determined through the normalized susceptibility data. discussed. 54 X-ray analysis revealed the occurrence of additional phases Francis Bitter National Magnet Laboratory, MIT — The resistance of single phase samples of YBa,Cu,07 and NdBaaCu,O, increasing with the Mn content. However, slight changes of the has been measured as a function of temperature In a magnetic lattice parameters and of the relative peak intensities for the field up to 23 tesla. The behavior of the resistivity between 120 K and T is consistent with the effect of three-dimensional orthorhonbic phase, were also observed, suggesting a small superconducting fluctuations in polycrystalllne samples of introduction of Hn in Cu sites. y,BajCu,O,. On the other hand, resist! vlty measurements In single crystals did not show significant excess conductivity * Work partially supported by FAPESP-SP and Pirelli S/A, Brazil. above Tc like the polycrystalllne sintered material. From the measured slopes of the upper critical fields (with H (| a-b plane and H _[ a-b plane) the anlaotropy ratio was calculated to be about 1 for both YBaaCu,OT and HdBa3Cu,07 single crystal MM-13 samples. Positive curvature in H vs. T data for H J^ a-b HIGH MAGNETIC FIELD STUDIES OF POLYCRVSTALLINE plane was not always present. .O, AND SINGLE CRYSTALS OF YBa,Cu,07 AND NdBa,Cu,07,» d JE TkR HM Supported by AFOSR grant F49620-85-C-0005. Session LJ Fusion II/MHD III 9:45 a.m.-noon, Wednesday, August 24, 1988 the determination of the modified conductor's mechanical U-1 properties. The techniques of determining the composite elastic SUPERCONDUCTING MHD DEVICES: THEIR PERFORMAN- moduli have been checked by load-displacement tests on samples CE ACCORDING TO COMPONENTS GEOMETRY,"P. Dal Vacchlo. of actual conductors. These samples consist of three-by-three A. Gart »nd G. M. Vaca, University of Rosa "La stacks of square tubing which are bonded together using glass fibers and epoxy. 5om« intrinsic limits MA inly du» to the! r low •Work peri:mied under the auspices of the U.S. Department of efficiency, ovara.ll size and w»ijht. Such ll*Uts arc Energy by the Lawrence Liver-more National Laboratory under essentially caused by the difficulty in creating Mag- contract number W-7405-ENG-4B. netic fields on high air gap. The increasingly rella- b 1 9 techno) ogy Ln mnuf actur ing superconducting n>g- air LJ-4 DETAILED DISTRIBUTION OF AC LOSS IN THE NET TF tailing up once more 3 preliminary study regarding the COILS, L. Bottura and J.V. Minervim, The NET Team, c/o Max Planck design for an electromagnet ic puap with superconduc- Institut fur Piaimaphyiik - The AC IOMM in the toroidal field coiW of a tive excitation colls, are carrying out an analytic Tokamak are a complex function of ipace and time. We have comput- study of the electromagnet ic field inside a conduc- ed the local field map of the DC toroidal field component! and the AC t Ln of poloidkl Seld component* throughout the TF coil winding pack of the NET machine. These magnetic field* have b«en resolved into component* taking into account the edge e/facts and tha iraitur* transverse (2 directions) and parallel to the conductor*. Thi* wat doaa for react Ion. The authors also conputa tha ••Chan Leal B.AB, and B. These time dependent field components were then used power supplied to fluid and the Joula I one* at a to compute the instantaneous and average AC losses (coupling and hys- function of the velocity of flow. Tha nustar ica I re- teresis) in the winding as a function of the plasma operating scenario. A special feature of thit analyii* is the presentation of the loss distribution along a developed pancake winding at different time* in the operating cycle. Thi* i* particularly useful as a heating input for a thermal analyst* of the forced-flow conductors. • Supported in part by ENEA (Italian National Council for Nuclear and Alternative Energy > by mains of Re- search Contract N° 2493/66 LJ-5 LARGE COIL TASK INSTRUMENTATION AND DIAGNOSTICS—A REVIEW/ J. W. Lue, J. F. Elli«, W. A. Fietz, M. S. Lubell, J. N. Luton, S. W. Schwenterly, C. T. Wil»on, and LJ-2 R. E. Wintenberg, Oak Ridge National Laboratory - The Large Coil PEVELOPKENT OF A FORCED-COOLED SUPERCONDUCTING COIL Task (LCT) w» aimed to develop large superconducting magnet* for WITH HIGH AVERAGE CURRENT DENSITY (DPC-TJ), T.Hamajima, fuiion reactors. Each of the six coil* built for this task was heavily in- A.Tanaka, H.Shiraki, H.Shibui, 'i.sanada, H.Naganima, M.Shimada, strumented with some 200 to 350 seniors and diagnostic taps to test its and T.Fujioka, TOSHIBA CORPORATION, M.Nishi, H.Nakajima, performance and characteristics. In addition, more than a thousand ten- K.Koizumi, Y.Takahasht, T.Ando, H.Tsuji, and S.Shimamoto. Japan sors were installed in the facility and teit-stand components to ensure Atomic Energy Research Institute - The main purpose of the safe and controlled operation of the toroidal test array. Through the DPC-TJ coil development is to demonstrate the realization of a three-year test period, some sensors worked consistently, some failed pre- maturely, some constantly gave useful information, some were rarely used, and wit yet others were vital in some particular test mode. The paper reviews 12 T, which meets tho requirement for the coils of the next the various types of thermometers, pressure gauges, flow meters, strain tokamaks. The DPC-TJ program is going on under the collabora- gauges, displacement transducers, acoustic emission sensors, field probes, tion between Toshiba Corporation and Japan Atomic Energy and other diagnostic instrumentation used in LCT. The difficulties with Research Institute (JAEBI), The DPC-TJ coll has a 2 double- some of the sensors, the usefulness, and the reliability of different groups pancakes with dimensions of 1.0m-ID, 1.8m-0D and O.llm-H. of sensors experienced in this task will be reported. The DPC-TJ conductor is a newly developed preformed-annor ' Research sponsored by the Office of Fusion Energy, U.S. Department first conduit, and of a pz&forrood thick one covering the first of Energy, under contract DE-AC05-84OR21400 with Martin Mari- conduit. The first conduit is provided for sealing of super- etta Energy Systems, Inc. critical helium, and the second one supports electromagnetic force and pressure load at coil quench. A model coil with full size dummy conductor, which was planned to establish this LJ-6 newly developed winding method, was successfully manufactured, PROGRESS IN THE MANUFACTURE OF THE US-DPC and its stiffness test was carried out. We have been develop- TEST COIL,' M. M. Steeves, M. O. Hoenig and J. E. Tracey, MIT ing a (NbTi )3Sn stirand of 0. 67JTITI dia • * which has the high critical current density of more tnan oQO *\/mm at 1 * T with Plasma Fusion Center -The 1.5 tonne, 2 m diameter, three low resistivity- The DPC—TJ coi1 is now under fabrication at doubfe-pancake poloidaf test coil wifl be completed and Toshiba and is scheduled to be tested in the DPC test facility at JAERI. shipped to Japan in 1989. The paper describes developmental and manufacturing procedures as well as problems encountered in the fabrication of the coil. The LJ-3 process is broken down into the following sequential steps: STRUCTURAL OPTIMIZATION OF PROPOSED ITER T.F. COIL [i] fabrication of the superconducting cable, [ii] fabrication CONDUCTOR,* C.R. Gibson, Genera) Atomics and J.R. Miller, Lawrence Livemnre National Laboratory - This paper presents the of the double-jacketed incoloy 90S cable-in-conduit structural optimization of a cable-in-condult conductor {CICCJ conductor (CICC), [iii] winding, conductor termination and which Includes a structural channel. This conductor was heat treatment, and [iv] final insulation and assembly of Initially developed far the T.F. colls of TIBER and Is currently being considered for the ITER T.F. coils. The structural the coil. Emphasis is placed on manufacturing details that optimization Is an Iterative process which begins with the are crucial to the successful fabrication of a large Nb3Sn determination of the conductor's composite elastic moduli and Poisson's ratios. These mechanical properties are found using coil. Examples are cabling procedures, conduit welding, both finite element and analytical techniques. The mechanical helium inlet fabrication, conductor lead bends, conduit properties are then fed Into models of the T.F. coll to removal, terminations, electrical joints and quality determine the electromechanical loads on the Individual conductors. The maximum stresses 1n the conductor are found by control. The wind-react-insulate manufacturing process applying these loads to the finite element models of the permits the inspection and repair cf any leak in the seam conductor. To reduce the stresses, modifications are made to weld without damage to the superconductor. the geometry of the conductor and the process begins again with •Supported by DOE Contract DE-AC02-76ET-51013. 55 LJ-7 counterflowlng Helium gas all the way down to the LHe bath 3) A system wich Includes an heat sir* ( LN2 or other fluid ) at an CURRENT LEADS WITH HIGH Tc SUPERCONDUCTOR BUS BARS, A.Matrons, Ansaldo Spa.DivisionsRicerche, A Rosatelli and intermediate temperature We show that, whichever the solution R. Vaccarone, l.N.F.N. Sezione HI Genova - The effects given by the will be, a sizable gain in comparison with standard current leads 2 addition of Superconducting Bus Bars to the current leads working can only be obtained if a material with a Jc higher than I KA/cm between room temperature and a LHe bath has been reviewed in is available. In case I and 2 the main limitations are given by the view of the possibility to use the High 1C Superconductors Several copper section at high temperature The reduced He consumption due to the disappearance of ohmic losses in the superconducting different designs has been considered, with Intermediate part causes a warm up of the copper section and premature run characteristics between the three extreme solutions listed below 1) The standard configuration with current leads cooled by away of the system In large systems, where LN2 or other fluids at counterf lowing Helium gas and superconducting bus Oars shunted by intermediate temperature are available, solution 3 can be a better copper. 2) Current leads and superconducting bus bars cooled by choice, providing a large cut in the cryogenic load to the system Session EK High Tc Superconductor Electronics II 1:30-3:15 p.m., Wednesday, August 24, 1988 Shapiro steps with microwave exposure, in a SQUID having EK-1 submicroraeter tnicrobridges. The maximum modulation voltage of THE OBSERVATION OF AC JOSEPHSON EFFECT IN A I5uV was obtained at 4.2 K. We confirmed the response to the YBaiCuiOT/Au/YBaaCu»O D.B. Schwartz, P.M. Minkiewith, magnetic flux up to 53 K. The variation of the critical T current with temperature near Tc('-64K) was of the form of R.E. Howard, AH. Dayem, L.D. Jadcel, E.G. Burlthardt and BX. Straughn, 2Ic "(l-T/Tc)-*'* , Telegraph-like noise of the voltage which AT&T Bell Laboratories, Holmdel, N.J. We have fabricated the first proximity exhibits switching between two or more discrete levels was effect device based upon a thin film oxide superconductor. The AC Jowphson observed in alJ of our SQUIDs regardless of the width of effect has been unambiguously demonstrated by the presence of microwave step 6 microbridges. The bump structure of Lorcntzian due to the when irradiated at frequencies up to 15GHz. The sensitivity to microwaves per- telegraph-like noise was dominant in the power spectral density sist* to 14K where the critical current is reduced to zero by thermal fluctuations. of the flux noise of the SQUID and limited the flux sensitivity The superconducting electrode* of the device were fabricated by using liftoff to in the low frequency region. The white noise observed above define a 1/im gap in a YBaiCuiOi electron beam deposited film on a SrTiOz 2kHz is l.^xio-^to/t^Iz being limited by the preamplifier noise. substrate. After annealing, the films had Te of 90K. The weak link was formed by depositiig a lOftm wide Au resistor acroti the gap and flash annealing the sample at 750°C for a few tecondt in a pure oxygen ambient to make contact be- EK-4 tween the Au and the superconductor. The Te and width of the transition of the CHARACTERIZATION OF HTS THIN FILM HF SQUIDS, electrodes were unaffected by the flash anneal. The 6/iV IeR product is in rough K. P. Daly, A. H. saver, R. Simon, C. Plan, A. Lee, M. S. Wire, TRW; agreement with that predicted by the conventional theory of superconducting J. E. Zimmerman, NBS Fellow - We have successfully fabricated RF- proximity effect devices. SQUIOs from Er,8aoCu3Ov films on SrTiOo and sapphire substrates. A periodic variation of the 30 MHz RF voltage as applied flux was varied has been clearly observed. Up to 10 steps in the RF V-l curves were seen. This demonstrates that the HTS microbridge, EK-2 acting as a single lux quantum switch, responds in less than 1.6 ns. One micron thick films were made by co-sputtering from three SINGLE TARGET SPUTTERING PROCESS FOR HIGH metallic targets followed by a high temperature anneal in flowing Op. Tc SUPERCONDUCTING FILMS AND DEVICES,* R.L. The microbridge and SOUID inductance were patterned in a (2 Sandstrom, WJ. Gallagher, T.R. Dinjcr, R.H. Koch, R.B. Laibowitz, mm)' film by ion milling. We suspect the actual weak link occurs at A.W. Kleinsaaaer, RJ. Gtmbiso, B. Bumble, and M.F. Chishoto IBM a grain boundary presumably in the microbridge. Measurements to TJ. Walton Research Center, Yorktown Heights, NY - We report a characterize the operation of these HTS devices will be described. simple, sinfle-tartet magnetron sputtering process involving an uncon- ventional sputtering geometry that allows reproducible fabrication of EK-5 high quality YBajCiijOu films from nearly stoichiometric targets. The FABRICATION OF SU6HICR0METER FEATURES IN Y-fia-Cu-0 process lends itself both to film growth with high temperature post SUPERCONDUCTING THIN FILMS, T.L. Checks, C.T. Rogers. P. anneals and to low temperature in situ film growth. The post-anneal England, S. Chan, H.G. Cralghcad and T. Vcnkatessn, Bell process has been optimized to routinely yield epitaxial films on lattice Coaamnicationa Research,. - We have explored the processes matched substrates that are fully superconducting at 86~90 K. Device required Co fabricate superconducting devices bassd on Josephson weak links. To this end, ve have ••ployed photolithography, structural have been made using conventional photolithographic pat- electron beam lithography and focusfd ion bea»s to define terning techniques and ion milling. Current densities at 77 K of up to patterns with dimensions frost several •lcroateter* to less than 6x10* A/cm1 have been measured on 10 /an wide lines. Simple thin-film one alcroMter. Ve have combined Che pattern definition with dc quantum interference devices (SQUIDs) have been operated at 77 K ion beaa pattern transfer techniques, including inert gss i in •llling and reactive Ion processes. The fabrication has be sn in liquid nitrogen and their noise characterized. done on filu both before and after oxygen annealing, with the best geosetrical control obtained by patterning before the 'Partial support for this work was provided by the Office of Naval Re- annealing step. Ohalc contacts were reliably stade by in situ Ar ion beaai pra-iputtsr and Au evaporation. Subalcroaeter wires, search under contract N000M-S5-C-036I. fabricated on a variety of substrates, behaved as scaled down bulk superconductors. Intentional damage can Induce weak link behavior although to date, the weak link properties cannot be EK-3 veil controlled. The structures defined by several fabrication LOW TtWERATUKE SYNTHESIS OF Y-Ba-Cy OXIDE FIUKS AND processes and their electrical behavior will be discussed. PREPERATION OF DC-SQUIDs, H. Matsuda. A. Matachi. and S. Kuriki, Research Institute of Applied Electricity, Hokkaido University - We have synthesized the superconducting Y-Ba-Cu EK-6 oxide thin films at relatively lov temperature without heat A SUPERCONDUCTING SHORT D1POLE AERIAL AT treatment after the deposition. Thus, they have small grains of 550 MHz USING YBCO WERE, C. E. Go ugh, S. Khamas. M. J. Mehier less than 500nm. DC-SQUIDs having two parallel raicrot>ridges snd T. S. M. McLean. University of Birmingham Consortium on High-Tc with constrictions of subsiicroneter to 40 un in width were Superconductors, Binninghim, UK and Dr. N. McN. Alton). fabricated fron the oxide filers. The SQUIDs with microbridges M. A. Htrmer, ICI Advanced Materials, Runcoro, UK. - of various widths greater than 2 us didn't operate as Josephson A superconducting 2cm dipole-aerial and matching network operating at devices even at 6.2 K. The temperature dependence of the 550 MHz hu been successfully implemented using a simple transmission critical current near Tc(VOK) was in a form of 2Ic<*(l-T/Tc)V2 line structure of self-supporting sintered YBCO-wire. Near perfect which! together with a parabolic I-V characteristic, suggests mitching of the 0.26 0 radiation resistance to the room temperature SO fl vortex-flow. On the other hand, we have observed the periodic source impedance ha* been achieved. Measurements of the frequency and modulation of the voltage with magnetic flux, together with power dependence will be presented. 56 Session MN High Tc Superconductors: Critical Currents II 1:30-3:15 p.m., Wednesday, August 24, 1988 nica. The subsequent composites were heat treated and MN-1 properties, such AS resistance vs temperature and the Meissner effect, measured. SILVER ENCASED HIGH TEMPERATURE SUPERCONDUCTOR RIBBONS PRODUCED BY ROLLING, C. A- Whitlow, K. C. Iyer, A- T. Male, J. C. Powell and G. R. Wagner. Westinghouse R&D Center - We have MN-4 investigated the fabrication by unidirectional rolling of ANIS0TR0P1ES IN THE HAGNETIC PENETRATION DEPTH AND CRITI- nominally 0.01 In. thick ribbons of sUver7YBa2Cu3O7/silver and CAL CURRENT DENSITY Of RBa2Cu£7_x (R • Y or Ho), KASURED ON their resulting microstructural and superconducting properties. MAGNETICALLY-ALIGNED POWDER COMPOSITES, D. K. Christen, Y. C. Cold pressed pellets in both the sintered and unslntered con- Kim, S. T. Sekula, J. R. Thompson, J. Brynestid, 8. C. Sales, ditions wore encapsulated in silver billets and cold rolled L. A. Boatner, and J. D. Budai, Solid State Division, Oak Ridge fabrication sinter/oxygen replenishment anneal on their National Laboratory,* Oak Ridge, TN 37831 — Powder particle crystallites (2 - 10 i*n in diameter) of RBa^ujO?^ (R - Y or core deformed plastically, the degree of grain alignment/ Ho} were suspended in a liquid organic matrix, ind the matrix prefer red orientat ion observed was not os crcat us had been allowed to solidify in the presence of an applied magnetic anticipated. Transport critical current densities measured field. Due to magnetic anisotroptes, the resulting composites in zero field at U and 77K were 580 and 125 A/cm2 respectively. were comprised of dispersed, uniaxially-aiigned particles having Although these values are low, they compare favorably to a common crystalline c-«x1s parallel to the applied field. From results from pressed and sintered powder. We believe that observed particle dimensions and magnetic susceptibility mea- further refinements in fabrication may be expected to lead to surements for fields applied either parallel or perpendicular to increased Jc values- Sicnilar, nore preliminary experiments the Cu-0 planes, we have Inferred anisotropies in both Intrinsic on che new bisauth containing, high temperature superconductors and extrinsic superconducting properties. Analysis of the have indicated that co-deformation of a silver conposite billet temperature-dependent low-field flux penetration yields the by rolling is easily accomplished and that the resulting anisotropy In the superconducting magnetic penetration depth \, that arises from superconducting shielding currents flowing either in the crystalline a-b plane or along the c-ax1s. This intrinsic superconducting parameter 1s found to have the same magnitude and relative anisotropy for both the Y- and Ho-based MN-2 materials. From the magnetization hysteresis in the mixed CUSRENT BEHAVIOUR OF TIfE METAL CLADED csrncu. state, we have derived relative anisotropies in the critical current densities Jc. This extrinsic parameter shows an an- Cd.Ba.Cu-O- ., S.S. Dubey and Ratna Kapoor, Univc iity of Delhi, Isotropy that anomalously Increases with temperature. These Delhby powdei - r SiTvecou^actlor cland Session LK Medical Applications 1:30-3:15 p.m., Wednesday, August 24, 1988 temperature shrink Tit); the coil thereafter rea£££cfdesign LK-1 operating values. The technology la also being^-ppiied to the SUPERCONDUCTING CYCLOTRON FOR MEDICAL APPLICATIONS,* design of a 250 MeV superconducting synchro^y^iotron for proton H.G. Blosser, National Superconducting Cyclotron Laboratory, therapy; this cyclotron can also mount jOJ^ectly on a gantry or Michigan State University -- Superconducting cyclotrons are can mount In a fixed position and£&e"cf several beam rooms via an typically 10-20 tinea lighter in weight than room temperature appropriate bean transport tly •Supported by Harper-Gra'ce Hospitals, 3990 John R, Detroit, HI. on an i3ocentric gantry so as to move on a full 360° arc about a supine patient in the rashlon of a typical cobalt or linear accelerator therapy unit. Such a cyclotron is now nearing LK-2 completion at NSCL and, when completed, the unit will be installed In one of Detroit's leading hospitals. The SUPERCONDUCTING MAGNETS FOB WHOLE BODY MAGNETIC Superconducting coi1 is an epoxy Impregnated, Intrinsically RESONANCE IMAGING, H. P. Murphy. Oxford Superconducting Technology - Superconducting magnets have achieved pre- (average over the winding) with peak field of U.6 teala In the eminence in the magnetic resonance imaging (MRI) industry. coil and 5.5 tesla in the Bean region. The coll is conduction Purther growth in this market will depend on reducing sys- cooled from a surrounding liquid helium reservoir which has the tem costs, extending medical applications, and easing the novel characteristic of providing vents continuously open to present siting problem. New magnet designs from Oxford atmosphere, which nevertheless do not spill Helium as the vessel address these issues. Compact magnets are economical to is rotated. Tne magnet, as first constructed, quenched si. a build and operate. Two 4 Tesla whole body magnets for lower-than-needed operating current due apparently to an error research in magnetic resonance soectroscopy (MRS) are now in allowing for the elastic modulus of the Insulating material in operation. ACTIVE-SHIELD magnets, by drastically reduc- on the conductor, thereby reducing the preload in the winding ing the maanetic fringe fields, will allow MRI systems with relative to design values. A retrofitted correction utilized a superconducting magnets to be located in previously inac- "stretcher" ring In the bore of the coil (installed via an LN2 cessible sites. An overview of these Innovations will be presented. 57 LK-3 LK-5 THE 600 MHz SPECTROMETER MAGNET SYSTEM AT FBNML, A 5 TESLA MM IMAGING HAQIET FOR IMAGING LABORATORY J.E.C. WilHama, Francis Bitter National Magnet Laboratory, ,MJT " ANIMALS*. Juts 1. CaroWn, NCC Corporjtton. and Htchiel A. A superconducting magnet system lias been built for the NHR Grctn. 5 Colton PUc«, OikUnd. CA 94611 - This Is • report facility at the FBNML. The field is 14.093 T which corresponds on the construction ind testing of tin first of i series of to a proton resonance of 600 MHs. The magnet consists of wind- HRI 1mg1ng aigntts for laboratory anialls. The NCC Mgnet ings of nlobiuo-tltaniuD and niobium-tin conductor operated in his a 33 ctnttattir uri bore >1th t design central Induction series, in persistent mode at 2.5 K. The room temperature bore of 5.5 ttsla vftlHXit acttvt sMtldltig and 4.7 tesla »Hh of the magnet Is 2 inches and the outer diameter. Including shim activ* shielding. The signet will be used for both Imaging colls, Is 14 Inches. This is a relatively compact construction and spectroscopy of living aniials. The active shield syste* and incurs stresses of up to 150 MPa In the niobium-titanium Is designed so that the 5 Gauss lint Is less than 3 otters conductor and 190 MPa in the niobium-tin. Any Increase In these froa the Magnet center when the Mgnet operates at design stresses during quenching must be United; particular attention field. This permits the Mgnet to be used within an nas been paid Co that. Persistent operation Involves supercon- elperiMnta! space coaaonly available within a university ducting joints between the two types of wire as well as joints building. between niobiuo-titaniux. Methods of construction and testing of these joints have been developed that allow simple remake and 'Supported by a grant froa the United States National test. Independent of the state of the magnet. These Issues, to- Institute of Health. gether with general construction techniques, will be described. LK-6 LK-4 A FULL-SCALE SUPERCONDUCTING RECTIFIER FOR POWERING A 4.7 TESLA MAGNET POR 31P MAGNETIC RESONANCE AN HRI KAGNET. J. Slkken«a? H.H.J. ten Kate. University of &PECTR0SCOPIC IMAGING. H. Haeda. N. Virata. T. Mada. T. Yazawa Twnte, Appl ted, Superconduct 1 vlty Centre, Enscbede, the and A. Sato. Toshiba R ft 0 Center, 4-], Ukishiaa. Kawasaki, Netherlands and (+) HOLEC HIT, Hengelo. the Netherlands — Japan. - A 0.3 • bore 4.7 T hifh homogeneity magnet used for The Introduction of high currents by current feedthroughs In 31P aasnet ic resonance imagiag has been constructed and a cryostat In order to energise a superconducting aagnet installed in the Toshiba R « D Center. The Magnet comprised a causes a considerable loss of approxlamtely 2 W/kA- This set of soleaoids. which attained the design current oi 95 A loss can be avoided for the greater part by applying a (4.7 T. 1.74 WJ) without qtieaching. although conductor motions superconducting rectifier as a cryogenic power supply [1]. were frequently observed during coil energizing. Diodes in the The thermally switched full-wave superconducting rectifier cryostat, which suppressed heating of shunt resistors, resulted Is an highly efficient converter which consists of a in fast rasp rates such as 3 T in 10 Minutes. The field superconduct ing transformer, two rectIfler swltches and inboffogeieity for the bare magaet was 300 ppa/0.1 • dsv, which eventually two coaautatlon switches. M*a finally reduced to be 6ppai/0.la dsv by both superconducting In this paper we report on a superconduct Ing aad rooa teaperature shia coils. The field decay rate was less rectIfler especial\y designed to load an experlaental than 0.05 ppm/bour. The aagaet system is currently used for 31P full-scale Mil augnet. Using a prlaary current amplitude of magnetic resonance iaagiar (or chemical-shift spectroscopic 20 A this rectifier can energise an MRI aagnet to a current imaging) experiment* on living animal* in the laboratory level of maxlaum 1000 A with a power of 250 U (0.9 MJ/hr.}. Design and constructional aspects will be dealt with In the paper. [1) H.H.J. ten Kate. -Superconducting Rectifiers", thesis University of Twente, April 12, 1964. Session EL Particle and IR Detectors 2:00-4:30 p.m., Wednesday, August 24, 1988 EL-1 EL-3 PH0T0C0NDUCT1VE RISPOHSS OP GRANULAt 5UPDLC0HWCTIHG OPTICAL RKSMMSI Of Y-Ba-Cu-O THIN FILMS AND FILMS. U. Strcfl. E.S. Snow, R.L. Henry, P.X. Brouiiard. J.H. WEAK-LINKS, * D. P. Otteiain, R. Drake, R. Patt, E. Claaaen, S.A- Wolf, **v*l Research Laboratory; H. Leung and R.V. K. Track, M. Radparvar, and s. M. Faris, HYPRES, Simon, TRV - The optical reiponaa of granular superconducting Inc., - We have exposed patterned and unpatterned filjM to infrared or visible light can be broadly divided into a Y-Ba-Cu-O fil«s to visible and infrared light at boloaetric response near the maximum dR/dT, and a response at tetmperatures froa 2 K to 100 R while measuring lower tamptraturta which peaks near or below Tc. Ve have changes in I-V characteristics. In a current-biased 1 2 extended our preliminary invettigatiom ' of the photo- aodef voltage shifts were recorded as a function of conductivity of granular filas of NbN/BH and Y-Ba-Cu-O by X.i*.. teaperature, and light Modulation frequen- •ytteMticallj varying a number of experimental parameters, cy. Experiments were conducted on saaples whose including biai current, temperature, light energy, and applied resistivity for T > To exhibited a "seaiconductor- magnetic field, tfe have found that the photoconductivity within like" teaperature dependence. These saaples were the two distinct response regions exhibits important differences then annealed to produce "aetal-like" resistivity in its dependence on these experimental parameters. In addition, behavior for T > To and the experiaents were the optical response of Y-Ba-Cu-O wai investigated for films repeated. We observed a decrease in responsivity prepared by different techniques (e-be*m evaporation, ipray after annealing. The Magnitude of a heating con- pyrolytit, magnetron sputtering) and for different R vi T tribution to the responsivity has been inferred by profiles, tfe will discuss the impact of these measurements on comparing the frequency and teaperature dependence to currant models for the photodetection mechanisa and on the a Model. implications for other contributions will development of broad band. fnat. sensitive, infrared detectors. be discussed. 1. M. Leung, U. Strom, J.C. Culbertson, J.H. Claassen, S.A. Supported by OMR Contract Huaber Wolf, and R.W. Simon, Appl. Phyt. Lett. ,50,, 1691, 19&7- N00014-B7-C-0229. 2. H- Leung, P.X. Broussard, J.H. Classsen, M. Oioftkj. S.A.tfolf, and D. Strom, Appl. Phvs. Lett. SI, 2046. 1967. EL-4 OPTICAL DETECTION IN THIN FILMS OF YBa3Cu30v* EL-2 M. G. Forrester, M. Gottlieb, J. R. Gavaler, and A. X. OPTICAL lWlmlllGmT BY SUPntBSSHX OP THE GAP Braginski, Westinghouse R4D Center - To investigate VOLTAGE III Mb MID Html JUHCTIOtS, * D. P. Osteraan, the feasibility of using high temperature H. Radparvar, mod S. H. Furls, HYPRKS, inc. - We superconductors as infrared sensors we have measured have Measured the shift in gap voltage in Mb and NbN the optical response of lithographically patterned junctions when exposed to light as a step towards bridges of y.BSjCu3O,. For wavelengths of 6328 A and producing an array of superconducting infrared 10.6 jim, epit-.anial films appear to show no evidence of sensors. Junctions were exposed to light froa a non-equilibrium response (breaking of Cooper pairs by HeMe laser of wavelength 632 m and a Xenon arc lamp photons), but only a bolometric effect (heating of the used with various hwnrtpa" filters froa 1 us to 11 sample by radiation) in the resistive transition is*.. In 10 un X 10 lam junctions responsivities as regime. This suggests that epitaxial films do not nigh M 5000 V/W have been achieved at a 1 usj wave- contain intrinsic linfcs weak enough to be modulated by length with a 50% reduction in responsivity by 11 the incident radiation. For 6328 A radiation, usi. At a chopping frequency of 27 Hz the MKP is mechanically chopped at 500 Hz, preliminary 6 X 10~x»W ud D' = 2 X 10' a Hr1/3/W for a measurements of a lOjim x 90[im bridge yield a bolome- tric responsivity of 2000 V/W, but a detectivity D* 1 Hz bandwidth at = 1 un. our •easureaents show 7 w that the responsivity is independent of critical of only 10 cmHz */W, five decades below the state current except for very saall values where there is of the art. The source and nature of the noise which a reduction in responsivity. The responsivity of limits D* are presently being investigated. junctions in series im additive and we will discuss We also present preliminary results of studies to results for a series of 432 junctions. optimize the optical response and noise character- istics of granular YBa?Cu307 films. Supported by ONR Contract Number Supported in part by AFOSR/SDIO Contract No. M00014-87-C-0229. F49620-88-C-0030. 58 of this study, as it pertains to stabilizing tin tunnel junctions against EL-5 deterioration due to thermal cycling. SUPERCONDUCTING KINETIC INDUCTANCE BOLOME- TER. J.E. SaumgeMi, DC- McDonald, and N.T. Larsra, National flu- "Work supported bv the U-S. Department of Energy under contract no. rf*u of Standards, Boulder, CO — We are developing a bolometer based DE-AC03-81ER40009. on the temperature dependence of the inductance of a superconducting micros trip liue. A device such as tbii has no Johnson noise; it can be impedance matched to an optimized SQUID preamplifier; and its bias EL-10 current is relatively unrestricted by self nesting. Thus, in contrast with PHONON-MED1ATED DETECTION OF X-RAYS IN SILICON conventional bolometers, il is theoretically limited only by phooon noise. CRYSTALS USING SUPERCONDUCTING TRANSITION EDGE A theoretical analysis of this bolometer demonstrates that an electrical PHONON SENSORS,* B. Cabrera, A.T. Lee, CJ. Mtrtoff, J.P. McVirtic NEP of about 7 x lf}~"W/y/Hs may be feaaible if phonon noise can be and B.A. Young, Stanford University; and B. Neuhiuser, San Francisco Slate made negligible. As a first step in exploring this idea we have designed our University • We are developing a new type of elementary panicle detector based on the ballistic propagation of phonons in insulating crystals at low initial experiments for much higher power levels. They are based on the temperatures. Our long-term goals arc to study low energy neutrino interactions use of an all-niobium kinetic inductance thermometer fabricated on a sili- for addressing questions on neutrino oscillations and neutrino mass, and to con substrate which has been specially etched to provide suitable thermal search for weakly interacting dark matter candidates. We will report on our conductance between the bath and tempentture transducer. This differen- recent advances using superconducting transition edge sensors on the surface of tial thermometer uses a commercial SQUID as the preamplifier. Results silicon crystals. These sensors, which are made from ihin films from these first experiments will be presented. photoliihographically patterned as an array of parallel lines connected in series, detect the phonon wavefront produced by the absorption of an x-ray within the silicon crystal. The transition edge sensors are temperature-biased slightly EL-6 below the foot of the resistive transition and current-biased slightly below the HOVEL SUPERCONDUCTING DIRECT DETECTORS FOR INFRARED AND latching critical current, the current level above which a normally conducting MILLIMETER HAVES,* P. L. Richards, Physios Department, U.C. region of the film grows due K> self-heating. Each individual x-ray event is seen Berkeley -- A discussion will be presented of the potential as a self-extinguishing voltage pulse with the pulse height proportional to the utility of two new types of superconducting direct detector total length of superconducting line driven normal. We have detected x-rays for infrared and millimeter wave3. First, the properties of an over the energy range 6-60 keV with typical rise times <1 }is and pulse lengths unconventional near-millimeter wave radiometer consisting of an <10 MS- SIS fxiiJE^T* cown~conv©r*ter followe^ oy aft IF Dand—pd^s filter* dnd an SIS dir*ect detector will be compared with those of the •Supported in pan by Department of Energy Contract #DE-AM03-76-SP00-326 conventional SIS heterodyne radiometer and the SIS direct detector radiometer. Potential utility for the novel configurdtlon is claimed for applications which require EL-11 detection of small fast signals which occur somewhere within a A NIOBIUM IASED SUPERCONDUCTING TUWEU.IKG JUNCTION broad RF bandwidth. It appears to be well suited to planar AS A HIGH RESOLUTION X-MT SPECTROMETER FOR ASTROFKTSICS, \1tho^rapned imaging arrays* Second, the properties of an F. Gar*, R. Engalhardt and A. Fsscock, B5A/ISTEC. D. Tvaranbold, optimized thermal infrared detector based on the resistive Univarsit* da Nsuchatal. J.H. Lumlay, R.E. SoMkh, transition of a high Tc superconductor will be described University of Caabrldg* / Cryogenic Consultant! Ltd - quantitatively. Provided certal" stringent conditions on Fr*ll*in«T7 raaults on Nb-Al-AIOx-Al-Nb Island typa tunntl thermometer noise and thermal design can be met, this type of junction! aa X-ray and alpha-particle dstactora arc rsportad. detector can find useful applications at infrared wavelengths Ht«iur«snts of tha Inductd X-ray and alpha-particla slfnala vira longer than the cut-off of conventional LN cooled photovoltaic mad* at taaparaturaa varflna, batvsan 4.2 and 0.5 Ktlvtn. Tha detectors in cases where slow response speed is acceptable. antrir resolution and lintsrlty of thai* davlcaa ara praaantcd and The status of efforts to achieve these conditions will be coaparad vith tha results aehlavad previously with Sn-SnOx-Sn describee. Junctions. The results «lso dsaonatrata the food thermal rscyclability of such Nb baaed devices. The possibility of using • Supported in part by the DOD. such junctions as energy apectroieatera in future apace Missions for X-ray astrophysics is discussed. EL-7 EL-12 OPTIMIZATION OF THE PARAMETERS OF A JOSEPHSON TUNNEL JUNCTION AS ULTRAFAST PARTICLE CHARACTERISTICS OF Nb-BASED JOSEPHSON JUNCTIONS AT A DISCRIMINATOR, R. Cristiano and P. Silvestrini, Istituto di TEMPERATURE BELOV I K, K. Ishibashi, Y. Oae, K. Takeno, T. Cibernetica C.N.R., Arco Felice, Napoli. ITALY • The search Sakac, Y. Pfetsuawto, A. Katasc, S. Takada", H. Akoh*. II. for the optimization of some junction parameters to realize a fast particle (radiation) discriminator is discussed. Such a Nakagava*, Kyushu University, and *Elcctrotechnica] Laboratory - kind of detector is based on the ultrahigh speed Superconductors have an energy gap in relation to Cooper pairs characteristic of the operation of a Josephson junction. The of -ice irons. Its order of magnitude is as saali as reV. When a radiation interacting with the junction will reduce ultimately the Josephson current. If the junctions is biased radiation detector is Made by superconductors» it has the at current values very close to the critical current, then the possibility of producing a such better energy resolution than in presence of radiation induces switches to the finite voltage the case of semiconductors. Joscphson junctions of excellent state. We investigate the general aspect of the switching operation in connection with both problems of intrinsic characteristics have recently been developed to make high speed noise and non equilibrium processes induced by the coaputors. These junctions have Nb/Al/Al-oaide/Nb structure. radiation. The discussion is carried out in terms of an This type of junctions has been used to Make the radiation effective radiation flux, namely the flux which produces a detector. Current-voItaRC characteristics uere observed at a number of switchings equal to that produced by intrinsic noise. Such a quantity gives a direct measure of the device tcipcrature down to 0.4 K. Leakage current was leasured under performances. The effects of some relevant junction application of aaxnetic field to suppress the superconducting parameters, as the junction area, the Josephson current current. Problems to be solved vcrc studied to detect x rays in density and the bath temperature, on the behaviour of the effective flux as a function of the response lime of the a good energy resolution. device are presented. EL-13 EL-8 A RF SUPERCONDUCTING ELECTROMECHANICAL DETECTION OF BALLISTIC PHONONS AND QUASI- TRANSDUCER FOR GRAVITATIONAL WAVE ANTENNAE,* M.F. PARTICLES IN SINGLE CRYSTAL NIOBIUM.* S.C. Dickson, R.W. Bocko. E.E. Dept., U. of Rochester and W.W. Johnson. Dept of Physics, Bland, G.P. Alba, T.G. Dignan, D.A. Strieker. R.T. Johnson. San Fran- Louisiana State University - An electromechanical transducer which is a lumped cisco Stato University - We have constructed thin-film devices on single element radio-frequency bridge circuit in which the motion of a resonant crystals of niobium, for ihe purpose of studying ballistic propagation of diaphragm modulates a capacitance has been developed for use on a gravitational phonons and quasi particles in this material. As detectors we have used wave detector. The low electrical Joss of superconductors has allowed us to tin tunnel junctions and tin transition-edge bolometers. A solid state achieve electrical quality factors of several thousand in a rather complex lumped diode laser is used as the phonon generator, and the thin films are iso- element circuit operating at 4 MHz. We could remotely balance the bridge circuit lated from the niobium by an anodic oxide layer. We will discuss the use 15 to one part in 200,000 which led to a displacement noise level of 1O nWrlz. of these devices as particle detectors. These techniques should be useful in many applications in which one wishes to *\Voik supported by the U.S. Department of Energy under contract no. measure any physical quantify which can be made to change a capacitance. By DE-AC03-81ER40009. these methods changes in capacitance of IO-30 P could be detected in a one EL-9 second integration time. CHARACTERISTICS OF HIGH-TRANSMISSION- EL-14 PROBABILITY TUNNEL JUNCTIONS FOR USE AS PARTICLE DE- LIMITING FACTORS FOP THE ENERGY RESOLUTION OF SUPERCON- TECTORS,'George P. Alba. Thomas G. Dignan. Stephanie C- Dick- DUCTING TUNNEL JUNCTION DETECTORS, R. Gross, U. Klass, and R. P. son, Robert T. Johnson, David A. Strieker, and Roger W. Bland. San Huebener, Lehrstuhl Experifftentalphysik II. University of TUbin- Francisco State University - We have studied tin/tin oxide/tin super- gen, D-7400 TUbingen, F. R. P. - The theoretically obtainable conducting tunnel junctions with oxide layers of varying thickness. We energy resolution of superconducting tunnel junction detectors (STJDs) is more than one order of magnitude better than that of '.vill present the I-V characteristics of these junctions, and describe their semiconductor detectors an0 makes these detectors highly inte- response to ballistic heat pulses. The properties of these junctions fis restirg for various applications. Up to now the experimentally particle detectors will be discussed. An electron-microscope study of the obtained energy resolution has been much worse than that expec- morphology of tin films lias been curried out. We will discus? results tec theoretically • The rodii^tion or tho energy rpfiOjution can 59 bo caused by inhonogeneities of the tunneling barrier, the de- tector material or the thermal cupling of the detector to the w lopt^ti fur GiLft!f*i?n£ Session MO High Tc Superconductors: Characterization 2:00-4:30 p.m., Wednesday, August 24, 1988 vary with sample preparation method, being smaller for MO-1 crushed 'chip' samples than for 'bulk' specimens prepared ABXrS-STUDIES OF HIGHLY TEXTURED YtazCujpg by ion milling. A variation of the twin spacing with grain H»lbrltt«r, »P. Walk. «H.-J. M»thea. "B. Haeu«tr, ••«. Ro- gilla, K«rnforaohunt>z«ntrui Xarlaruh* GmbH. IK II, Poitfach size has also been noted and possible reasons for this are 36«0, D-7500 Xarlwuh*) * Unlvcrslttt Karlaruha, IEKP. Poat- discussed. r*ch 36*0, D-7500 Karlaruhat •» Unlvtrslty Twtnte. P.O.Box 217. N-75OOAE Enachtde - yBajCu^^ aputtar deposited cold on * Supported by the Basic Energy Science Division of the Al-0, and on HcO growa in 02 annaallnc apltaxlally to a tran- aplrtnt, aupareomJuotlnf flia with Te • 00 K. The unacraped Department of Energy aurfacaa of th«ae fllaa ara aaooth shoving XPS lines changing with photoelactron taka-off angle. This enhanced data baae •llovs to separate the different Chenleal coapounda {hydr- MO-4 oxide, paroxlda, carbonate, carboxyle, cuprata, graphite ...) TRANSPORT AND STRUCTURAL PROPERTIES OF Di-Sr- and to obtain their apatlal distribution. This then yields the Ca-Cu-OXIDE THIN FILMS PREPARED BY REACTIVE chaeUoal compounds, their aaount and their distribution Mklng SPUTTERING, D.W. Facef, M.J. Neal, M.M. Matthiesen, up tht cuprata and the cinder wnara tha lattsr growth, with J.T. Kucera, J. Crain, J. Souza, K.E. Wi11lams, J.M. Oj-annaal at internal and axtarnal surfacaa. The cinder atoi- Graybeal, T.P. Orlando, and D.A. Rudman, Massachusetts chlottatry gives insights in the chaolatry going on 02 anne- Institute of Technology, Cambridge, MA 02139 aling. Below the clndar the signature of 4 -axis textured Highly oriented superconducting thin films of Bi-Sr- YBajCujOjt surfaces ara Identified, showing that a Ba-oxide Ca-Cu-oxides have been reproducibly prepared by reac- layer foraia the stable surrace. This BaO surface coats CuO; tive magnetically-enhanced triode sputtering using and Y-oxlda layara yielding so art intrinslcly Insulating layer three separate metal targets (Sr, Ca, and Cu-Bi). The or about IM aurfaca. Tha Ba in superconducting cupratea shows films were deposited on A12O3, SrTiO3, and yttria sta- a laval shift dlffarant froc the BaO aurface and froa Ba in bilized zirconia conducted which show that the twins observed optically Tc supexoondrators with tezturo shev intenedlAte properties correspond to those seen using TEM and are not produced latvMB mgia capitals aM usual slatend pallets. Ws have by an optical interference effect. Using electron channeling, prepared aoo «ojpl« by a wHfled oltrate gjn&lsl£. mis equations have been formulated which allow optical determination of the true spacing of twins present in a •stood of preparation allow to reduce tha mater of crystal selected grain as well as the orientation of that grain. The denote, sol achieves high density mt«rlMs vlth good average twin spacing measured in TEM has been found to properties. An «^«H"g In a reaatlve 60 fttaospbST6 ljproves t-fr density 3C determined by four-probe method was ao high aa 2 • 10? A/cm2 at T = 77°K. The voltage-cur- coupling, in this paper, we restrict the ^""'""lon to the rent characteristics were measured by current pulse mcs analysis of the rmgn**-^ torque result*. The shape of the technique (TP = 5° ) using microbridge3 1*0.25 2 thua mm in size. Ju j >. jc V — exp ((j - JCJ/JQ) torque lst«wlty, recorded as a, function of the angle con corresponding to the flux-creep phenomenon. A power m jr»pi^iT^9r^ jy d prBfersBtlai orleDttttioo of tJw law V — (j - j^ ) (m = 4 r 6) observed at hielior current Ievel3 oeema to be connected with n nonli- Tbe variation* of the torque intensity with, the •agDetio f laid near flux flow. An avelanche increase accompanied Is also iinMutad and dlsoussed. by oscillations of the sample voltage V(t) was observed during the current pulse at j >- 8- 1CVA/cm^. A theoretical analysis of the thermal instaDility •Laboratori *i superconductors are now known to exist: La;.lAlCuO4 (A = alkaline earth) has Tt as high as 45 K, RBaiCujOr 61 Session LL Energy Storage, Generation, and Switching 2:00-4:30 p.m., Wednesday, August 24, 1988 with emphasis on the influence of operating temperature from liquid helium to liquid nitrogen coolant system design, LL-1 conductor configuration, and consequent energy econcuica of the TRANSIENT CHARACTERISTICS OF PARALLEL RUNNING OF THE machine. These axe related to the current and projected 2OKVA SUPERCONDUCTING SYNCHRONOUS GENERATOR AND A CONVENTIONAL performance of a novel conductor concept presently under development. characteristics of parallel running of the 20kVA LL-5 PRACTICAL EXPERIENCE ON THE OPERATIC* OF A 330 kVA Is connected through reactors (artificial transmission lines) SYNCHRONOUS GENERATOR VITH A SUPERCONDUCTING FIELD WINDING, • H.v.Lorenzen, H.-P.Groter and U. Enol, Technical University of generator (20kVA) Is connected to the terminal of the Munich - Since eight years theoretical investigations and experiments hive been carried out at the Technical University of Munich on a 330 kVA synchronous generator with a super- generator (SCC) in pover system. The Items of the tests ore conducting field winding. The superconducting exciter winding of 2 pole external pole synchronous generator is indirectly three phase grounding fault test and so on. Frora the cooled in a sloied coaling circuit with supercritical heliua. The test program carried out in 39 teat cycles (every test cycle keeping more than one week) enveloped extensive tests on the stationary and transient behaviour oi the generator. The variation or oiroacurc current of SCO (Jurlnc s transient ne i* 1 nd paper summarizes all practical experiences and espirxcal is extremely larger than that of the conventional one. results which received within this 39 test cycles.On back strokes, difficulties ind probleis concerning the synchronous generator and the whole test setup too is reported m detail. A special point oE view are disturbances in defence system of the Culture of Japan. superconducting Eieldwinding produced by eddy-currents. In several earlier publication* we reported on test results we got from this generator but we did not give informations on LL-2 practical experiences and empiried results. USIHC A MALL HY1MD PULSE POHEK TRANSFORMER UNIT AS The investigations were supported by the Deutsche Forschungsge- COMPONENT OF A BIGH-CUUENT OPENING SWITCH FOR A RAILGUN, E. M. meinschaft. V. Uung, R. E. Bailey and P. H. Hlchclt, General Dynaalcs Spaci Syacaaa Dlvlaioa - The Hybrid Pulse power Transformer (HPPT) (r«f. 1) is • unique concept exploiting the naturally faac super, conduct of to normal transition process of a super- LL-6 conductor. When used la the fora of a Hybrid Transformer CONTROLLER ACTION AND CONTROL OF A 330 kVA SYNCHRONOUS Current-zero Switch (HTCS) (rcf. 2), this creates an approach GENERATOR VITH A SUPERCONDUCTING FIELD WINDING. • H. Bischoi, la which the large, high power, high current opening switch in H.-P.Gr6ter and H.U.Lorenzen - Since one year there were done a conventional railgun system can be eliminated. This theoretical and experimental investigations on the control of a represents an innovative application of superconductivity to 330 kVA synchronous generator with superconducting field pulsed power conditioning required for the Strategic Defense winding. The generator is connected with a pover supply ot in Initiative (SDI). The current paper will discuss the design island operating. The superconducting field winding of the two and analysis of a 100 KJ unit capable of switching up to 1 HA pole external pole synchronous generator has a closed cooling at a frequency of 1 H2 and with a system efficiency of greater circuit, which is indirectly cooled by supercritical helium. than 90Z. Test results from smaller engineering test aodel» The generator ia equipped with a digital control of the exciter and circuit analysis using a computer code called SPICE will current and a digital regulation of the active and the apparent also be discussed. power. The digital control is realized by microcomputers. In this paper is given a summarize of test result on the control- led operating ot the generator under stationary and transient Rcf. 1: H. A. Hllal & E. M. W. Leung, "Energy Compression and operating condition!. Measured values of currents, torques and Transfer using Hybrid Pulse Power Transformer speed were compared with calculated quantities. Additionally is (HFrTr, presented at the 6th IEEE Pulsed Power reported on the problem to include the thermic circuit into the Conference at AilIngtoo, Virginia (June. 1987). concept of control. Ref. 2: M. A. Hilal, "Hybrid Transformer Current-zero The investigations sponsered by the Deutsche Forschungsgeaein- schaft listed above for reference 1. LL-7 A COMPARISON OF THE CONDUCTOR REQUIREMENTS FOR ENERGY LL-3 STORAGE DEVICES MADE WITH IDEAL COIL GEOMETRIES." W Hassenzahi. DEVELOPMENT OF LA1GE SUPERCONDUCTING ROTATING Lawrence Berkeley Laboratory • Superconducting Magnetic Energy Storage (SMES) plants MACHINERY, C. J. mole and S. K. Singh, Vastinghouse UD Center have been proposed in both solenoids! and toroidal geometrici. The former « efficient in terms of the quanliiy of superconductor required per unit of Mored energy. For certain - Large superconduction rotating aachinea are being developed applications, where a fringe field could be a problem, the toroidal geometry, which requires at worldwide. The use of superconductors to reduce the electrical least a factor of two more material hat been proposed. In addition to the solenoid and toroid, power dissipation in power equipment baa been a technological other geometries are possible such u linear mullipolei and spherical coils. These geometries possibility ivir linci the discovery of superconductivity, even have been considered for use in applications other than energy storage, though the stored though their use in power equipment regained an impractical energy and iis scaling are important. In this report, the effectiveness (quantity of draaa far a long time. However, scientific and technological superconductor/stored energy) scaling relations arc developed for various coil geometries progress in superconductivity and cryogenics has brought this dream much closer to reality. Results obtained so fax establish the feasibility of these machines. Analytical •This work was supported by the Director, Office of Energy Research, Office of High Energy developments have been providing a sound basis for the design and Nuclear Physics, High Energy Phyiics Division. U.S. Dept of Energy, undei Contract of superconducting machines and results of these design studies No. DE-AC03-76SF0009S, and by the Electric Power Research Institute.. have thowa iaproveieats in power density of up to a factor of 10 higher than the power density for conventional machines. This paper describes the recently completed U.S. programs, the LL-8 current foreign and U.S. programs, and then proposes a U.S. development program to maintain leadership in the field. LIGHTWEIGHT POWER BUS FOR A BASELOAP NIICLEAP RECTOR IN SPACE, Charles E. Oberly, Dennis J. Hoffman, and Lnv.pl 1 D. Hassie, Aero Propulsion laboratory-Environmental and induced interactions with the power distHbutfnn/pnwer proCPSSinq 2. S. K. Singh, 5O1-3Y56E, ffestinghouse UD Center, 1310 subsystem can hpcome a serious prnbrem fnr power systens Beulah load, Pittsburgh, PA, 15235; (412) 256-2137. rated at 10's to 100's of kilowatts because thp power 3. No preference. transmission hus weight and/or vnltaqp will increase dramatically. Utilization of new ceramic superconductors at 1000 A/cm*, which has alrpady heen defnonsfrated at 77 K, in a concur tor conf i QU i"a t * on car' elirninatp DO t n ous WP i Qh t d nd LL-4 distribution voltage problems in A hiqh power satellite. Thp IMPACT JF HIGH TEMPERATURE SUPERCONDUCTORS ON PULSED analytical results dernonstratp that the superconducting POWER SYSTEMS, 5. K. Singh, J. H. Murphy, P. V. Eckels, coaxial power transmission bus can o^*er sianificant benefit* C. J. Mole, A. T. Male, and C. K. Jones, ffestinghouse RID in rprJuced distribution vrjltanP and weight. Thermal losses Center - The unavoidable ac losses in the windings of pulsed have also hppn calculated and ba^ncpd against rpfricjpr*t >nn power system components such as generators and transformers capabilities. impose constraints on the use of superconductors for these applications and frequently make the use of cryogenically cooled conventional conductors more cost effective. High temperature supercoaductiag (BTS) materials, such as the LL-9 recently discovered ceramic compounds promise an extended range ECONOMIC POTENTIAL OF APPLYING HIGH Tc SUPERCONDUCTORS of trade-off options in the winding design parameters which TO MAGNETIC ENERGY STORAGE,* I.-T. Eriksson and J. Korpijarvi, could lead to a broader range of attractive applications than Tampere University of Technology, Finland - Enorgv rnanajt 62 1 tSMES) combines excellent efficiency with an acceptable cost systems. * Many solar-power bases are constructed in space, level. According to our earlier calculations moderate size nag- oceans, and deserts. The each solar-power base has a nets, say 500 MWh, compete yiih gas turbines and pumped hydro, superconducting magnetic energy storage (SMES) system. The as long as the daily discharge time is less than 3 hours. High magnets are sustained by rock on land and by water-pressure temperature superconductors have been est. lasted to decrease in ocean. The pressure of the magnetic field of 10 T . about 400 capital costs 18 Z. Further cones a notable decrease in running 2 costs due to the cheaper coolant and lower service costs. SHES Kg/cm , corresponds to the water pressure in the depth of 4 km which is the average depth in oceans. The electric power applications: power buffers for long transmission lines, power from ihe space is transported by microwave to the earth bases sources in "peaky" industrial areas, diurnal load leveling etc. which have the SMES system . The earth bases are connected One objective of our current activities is to establish with countries and cities in the world by superconducting a scheme of evaluating the capitalized energy price of a storage transmission cables. The superconducting cable with 10 cm in system of given capacity. Capital costs due to size, mechanical diameter can transmit the whole electric power used in the structure and thermal insulation will be weighted against the 14 7 running costs due to liquid nitrogen consumption. A flow diagram world (10 W). if Jc of the cable is over 10 A/cm* and the electric power is transmitted with lOOkV. The GEPSC project computer runs will be presented. The p.iper will include a case would need about 10'' S for 50 years. The cost per year study of the economic impact of a storage systea on a local corresponds to about one tenth of whole military fund per year network comprising extraordinary but realistic peak loads. in the world. The cost would be rather cheap in order to solve the world energy problem in future forever. 1) H. Ihara S K. * Supported by ASEA Brown-Bowery, Vattenfall Ab, ACA Ab, Scandi- tror.ix Ab, the University of Lund, Imatran Voioa Oy, Outokunpu Togano: "Super-conducting Materials" (Tokyo Univ. Press) p.221 (1987) (in Japanese). Ovr iiuurre Cleanrooni Ov and the Industr ial roundat ion o J the Nordic Countries. LL-13 LL-10 THERMALLY AND MAGNETICALLY CONTROLLED SUPERCONDUCTING EXPERIMENTAL RESULTS OF AN EXPERIMENTAL THREE- RECTIFIERS . G.B.J. Mulder. H.H.J. ten Kate, H.J.G. Kroos- hoop, and L.J.M. van de Klundert, University of Twente - PHASE ac SUPERCONDUCTING ARMATURE. Y. Brunei. P. Tixador. P. Superconducting rectifiers can be applied as current Vedrinc. CNRS - CRTBT - LEG. BP 166 X, 38042 Grenoble Cede*. France - supplies for high-current superconducting colls. Thus, Based on the development of ac superconducting cables, ac application of high-current Input leads Into trie cryostat can be avoided. The rectifier converts an alternating current of Modest superconductivity in electrical engineering has now started for study in France. amplitude to a d.c. current level that Is suitable for the Power transformers and limiters, full superconducting generators are superconducting coll. Basically, a rectifier consists of at least one superconducting transformer and two superconduct- investigaied by Alsthom. CGE-Marcoussis and CNRS. As a first siep in the ing switches. The MLXIBW obtainable power Is proportional realization of a full superconducing synchronous machine, i three-phase the operating frequency of the rectifier and Is usually Halted by the act 1 vat 1 on and recovery 11 MS of t he armature has been manufactured and tested with a normal rotor inside. switches. Therefore, we have Investigated different typed of switches. I.e. theraally and Magnetically controlled ones. Cryogenic and electrical tests have been made during more than The aajor purpose of this paper Is to point out the 100 hours, including transients, connection to the 50 Hz power system and differences between both Methods of switching and to discuss asynchronous start-up and operation. the consequences for the operation of the rectifier. The discussion Is Illustrated by Beans of experiment*] results These first results are relevant for the next step of the experiment which of two rectifiers which were developed at the University of Twente. These rectifiers have an Input current of 30 A. an is to complete a full superconducting machin with a superconducting Field: this output current of over 1 kA and an operating frequency of a component is now under construction. few hertz. With these rectifiers a load coll can be energized wlth a power of 300 U (1 HJ/hour) and an This paper reports the electrical results obtained with the three-phase ac efficiency of 97 'A. superconducting armature. These Invest 1gatIons In the prograaae of the Foundat1on LL-11 for Fundamental Research on Hatter (FOM) have been supported by the Netherlands Technology Foundation (STU), A TWO-PHAS? R'LL-WAVE SL'FERCONDUCTING RECTIFIER, T.Arlga ard A. Ishiyana , Depar*=*r.t ;if Electrical Engineering, Wageda I'm ver&ity--- A '.va-jrf.ase full-wave cuper?cndueting rectifier r.as been ievelcp^.i as a assail cryegenic pouer Btipply cf LL-14 s-jperccr^iirting aagrets :'or magnetically levitstion trains. CALCULATION OF PROPULSION FORCES IN EDS-MAGIEV TRANSPORT Tr.ese Eagr.etfi will be operated in th? peralsten* current ocde. SYSTEMS WITH SUPERCONDUCTING COILS, M.Andriollo, G.Hartinelli, However, Dial! chicle IORS^C caused at resistive Joints and sc M.F.Moiaio, and A.Morini, Department of Electrical Engineering, University of Padova, Italy - The nigh speed magnetic levitation T-frefcre, lcw-pcuer cryogenic pewer supples will be required tc ccopensate ?zr the reduction in sa^r.et current. The presented cup^rrjr.Ju.-'ir.i; rectifier consists of two identical to that of practical realization in Japan. In such iystens the full-wive rectifiers — rr.ec'.^ in series. Mair. canponentu of vehicle levitation nay be of electromagnetic (EHS-HAGLEV) or of •?a?h rpirrifipr are a trcHal chape Duperconducing cet-up electrodynamic type (EDS-MAGLEV), while the propulsion is gene- rally obtained by aeans of long stator linear synchronous notors aicr: 3 augnf.icaliy awitcn because nf the need to avoid the (LSH). In the EDS-MACLEV system superconducting coils are used influence cf the eagletic field produced fcy nagneta for both to levitate the vehicle and to produce the LSM excitation jevitatior., guidance- and propulsion on the switch and to Unit the size cf the whole rectifier system. The aivantagea of this field. The amature it usually supplied by cycloconverters.which rectifier are ac follows; i.'Z-cad current is increased saaothly. provide variable frequency currents. The use od superconducting 2.) Single operation la enabled uhen one rectifier breaks down. aagnets is principally related co the following advantages: 1) The teat results -ic-ir.g i 47.5 nil load oagnet at 0.2 Hz and 0.5 high values of levitation gap, due to high magnetic fields; 2) Hz operations are d^Gcrited. Froo the experinents and the on board magnets weight extrenely reduced; 3) elimination of ex sinflations, the transfer efficiency in examined and the ternal supply for the vehicle nagnecs. In the paper aa analyti- cpUes! deoigr. of therc&lly controlled switches is discussed. cal method is developped in order to calculate the propulsion force produced by the air core LSM of EDS-MACLEV system* on the LL-12 grounds of the variation of the electromagnetic energy stored in the field and armature coils. Unlike others, the method takes in GLOBAL ELECTRIC-POWER SUPERCONDUCTING-CABLE to account the finite thickness of the coils and is applicable (GEPSC) PROJECT FOR WORLD ENERGY-SUPPLY IN THE 21 TH both to overlapped and to non overlapped stator windings. As ex CENTURY. H. IHARA. Electrotechnicat Laboratory, Tsukuba, ample of application the developped relations are applied to an Ibaraki. 305, Japan -- GEPSC (global electric-power experimental LSM propelled EDS-MACLEV system, for which it is superconducting-cable) project is a plan to supply the world considered both the real case of non overlapped and the theore** energy-demand in the 21th century with the combination of tical case of overlapped stator winding. superconducting cable and magnet systems and solar-power Session MP Nb3SN: Measurements 3:30-5:30 p.m., Wednesday, August 24, 1988 the tt- MP-1 partic nt laboratories The VAMAS TWP recently roaplcted VAMAS INTKKamPAKISUN UK CHITIIAI. CUKHENT MEASUREMENT IN NL3Sn WIHfcS. H T.nhikdH,,, K Itoh. II Wad.i, I) (kjuld. II Jones. < K Wall ITS. I. K (Joodnch, 1 H Khin ami S I. »ray Japan. EC .ind US each supplied one ault if i laaentary Nb3Sn wire. (VAMAS Ti-chniral WorkinK 1'arly) Wir*> A is an internal Sn diffusion processed one with pure Kb VAMAS stands for ihr Vfrs.nltes prujeits .i»ons suaatt parti cores, having an HC2 of~l^T Wire H and C are bronze process c ip.int countries on Adviin 63 critical current was Measured in the field rangi- of 6 20T. There were few restrictions for aeasureaent at individual labo MP-4 ratnries. As back-up data, longitudinal homogeneity and stress THE CRITICAL CURRENT DENSITY THROUGHOUT THE effect of the wires were also studied SUPERCONDUCTING PHASE OF MULTIFILAMENTARY Nb3Sn WIRE FOR FORCED FLOW FUSION APPLICATIONS MEASURED USING THE BEAN- about 16% and that for wire B and C is about 7V The detailed CAMPBELL AC HACNETIZATION TECHNIQUE, D. P. Hampshire and D. C. results of this world-wide intcrcoaparison, possible origins Larbalcstler, Applied Superconductivity Center, University of of the deviation aiODR participant laboratories and preliminary Wisconsin - AC magnetization measurements have been completed recoMiendations for critical current BeasurcBcnt based on the on a multlfilamentary NbjSn composite wire which is a present cooperation will be reported. candidate for fusion applications. Using these data, the critical current density (Jc) has been determined using the Bean-Campbell analysis in the ranges B c 10 Tesla and 4.2 K ( MP-2 T c Tc. The field and temperature dependence of Jc is derived. Technical operating parameters required during Nb3Sn CRITICAL CURRENT MEASUREMENTS ON TUBULAR forced flow conditions are explicitly determined. FIBERGLASS-EPOXY MANDRELS,* L. F. Goodrich and S. L. Bray, National Bureau of Standards, Boulder, CO 80303 - A systematic study of the effect of saaple mounting techniques on the super- conducting critical-current measurement was made in conjunction MP-5 with the VAMAS (Versailles Agreement on Advanced Materials and THE CHARACTERIZATION OF NfcSn SUPERCONDUCTORS Standards) round robin oeasurenents. A seenlngly small change FOR USE IN MAGNETS OF 19 T AND GREATER1. LT. Summers. in mandrel geometry can result in a 40ft change in the measured J.R. Miller, and M.J. Strum, Lawrence Livermore National critical current of a NbjSn sample at 12 T. This Is a result oi a change in the conductor pre-strain (at ', K) due to variation Laboratory, - Proposed high-field, superconducting magnets in thermal contraction between thick and thin walled, for NMR spectroscopy are pushing the limits of Nb3Sn fiberglass-epoxy cooposite, (G-1D) tubes. An approximate technology. Here we will review the state-of-the-art and measure of the thermal contraction (from room to liquid nitrogen discuss our characterization of advanced Nb3Sn materials temperature) variations indicate a 0.2% greater contraction for the thick wall tube. This contraction difference, combined with intended for use in magnet systems designed for operation strain sensitivity data, gives calculated results consistent at fields equal to or greater than 19 T. We will discuss the effects of heat treatment variation on the microstructure publications on the thermal contraction of G-10 have addressed and electrical properties of Ta and Ti doped NbaSn, the the plate geometry but not the tube geometry. The contraction effects of applied strain and fatigue, and physical of a C-10 plate is highly anisotropic. The radial contraction of a tube is different froa the contraction of a plate because properties including dimensional changes during reaction Che circumferential fiberglass is put in hoop conpression by the heat treatment and cool down. In addition we will discuss epoxy and the resulting contraction is a conpetition between the the prospects of fabricating high field NMR magnets. two structural coaponents. This appears to be the source of the * This work was performed under the auspices of the U.S. Department of Energy by the -Lawrence Livermore National * Research was supported by the U. S. Department of Energy, Division of High Energy Physics and Office of Fusion Energy Laboratory under Contract W-7405-Eng-46 and partially under Interagency Agreeaent No. DE-AIOI-76PR06010. supported by a grant from the National Institutes of Health under contract RR00292. MP-3 MP-6 MEASUREMENTS OF THE STABILITY MARGIN OF A Nb Sn EFFECT OF TRASSVERSE COMPRESSIVE STRESS Oil THE CRITI- 3 CABLE-IN-CONDUIT CONDUCTOR. T. Ando. M. Nlshl and S. CAL CURRENT OF CABLED S*sSn CONDUCTOR, ShlisRoto, Japan Atonic Energy Research Institute - The 3. Jakob and G. Pasztor, Faul-Scherrer-Institute (PSI) ibllity isrgin of a single quadruple of Nb Sn/Cu composite 1 3 523 * Villigen, Switzerland. - A test apparatus was designed and enclosed In a round stainless-steel tube has been and built for the investigation of cabled conductors subjected sured by using an inductive heater. The strand has a to transversal load. The apparatus permits measurement of dl iieter of 1.04 •• and a copper fraction of 69 *. The compressive stress on a multistage flat cable while a trans- fr.ictlon of heliui In the cable space Is 35 X. port current is applied to one of its constituent subcafcles. Me, isure«ents of the stability Bargin were carried out by With the apparatus, the critical current behaviour of a varying the transport current, the external lagnetlc field solder-filled NbjSn cable made by the external diffusion and the Initial internal pressure. The hellui flow rate Is process, exposed to transversal loads up to 200 KPa was in- always zero. The Halting transport current, which Is the vestigated. A field dependent degradation of the critical boundary value between the upper and the lower stable current has been found. Solder-filled cables as used in large region, were observed slailar to NbTi Cable-In-condult current applications seen to be less sensitive to tranaverse conductor. The Hatting current density over the cable space at 12 T was 100 K/w* corresponding to 58 * of the conpressive stress coapared to single wire results reported critical current. This value didn't depend on the Initial recently by other laboratories. Internal pressure in the range of 3-10 atoi. The upper and lower stability largln were aore than 200iJ/cc and less than 50 iJ/cc, respectively. Session MQ High Tc Superconductors: High-Frequency Responses 3:30-5:30 p.m., Wednesday, August 24, 1988 MQ-1 MQ-2 MICROWAVE STUDIES OF GRANULAR SUPERCONDUCTIVITY MICROWAVE SURFACE IMPEDENCE IN A SINGLE A M. Penis. Defmtmrnotnvva. L'umMv ol (Mfanm. Btmy CA 91720 CRYSTAL OF ETJB^CU^OT.C, W. W. Fuller, F. J. Rachford, and K W.BIazey. IBMZmdKamtiLttmnrr. M03XtxUitai,Swiutrlml W. L. Lechter, P. R. Broussard, J. H. Claassen, L. H. Allen, Naval NGcnrwivt wjiorfooci in tow majaoc 1Mb is > vwy smsttivc comdas inOkaor of Reseaich Laboratory — We have studied the microwave properties of a Similar nqmowMaimy. wbdi In tea Jmn»1 i» Uni **/ « arctmun' am lad- single crystal of Er1Ba3Cu30;_ij. The crystal was placed at the bottom of ndKar mfm ad is > s«tttam. same of sgrfaot roisunor. Bilk franlany a a rectangular TE103 copper cavity whose resonant frequency was 9.2 GHz. pa [Bundle for gaorowave abjorpwa a fe tuawic tnj b-Mqimn loparcowtuaors' < The Q of the combined cavity and sample aa well as the frequency shift •ad u cmnc Owml-ftK coapouds * TK *»orpooo is aaptaaJfy Irje beawe were monitored as the system was cooled. Below about 50K the mknrwive najMiclkMs arc cncanul wiojia pain bandana "twe nufoajc fta measurements became limited by the copper cavity. Close to the superconducting transition, about 90 K, the real surface impedence is two inaiallv tarns pnk saaytaa. 71K ancrowave afesorpton HUB above Hc] « lbi twn fnias. MniLlawl microwave absorption lifoals from graoular onmics sbow orders of magnitude higher than that calculated from Matt is and Baideen's1 formula. This could be due to in homogeneities in the oxygen cnik* twtawr waa paavaj aad Ojpinmaj of Dm ovtr > moMMxx eyde.'* In concentration in the crystal. The temperature dependence of the surface iin(k-a>TM YBajOuOr-j tbe *!or[Oo(i ma from UK molioo of fta wihk Iwin- 1 impedence below the transition temperature will be compared to piaMdaaanboudam.wMdiaresiailariapaiiibouxlarKS. Modulated absorption Mattis-Bardeen predictions. The effect of small magnetic Reids, less than nfials from doauat boodanti stow Macroscopic flra q\iaatizw>a and microwave 100 Gauss, will be discussed. We will also present results on composite aduboo nfiemv; of Ike behavior of a bcaniy danped Josephstm nnsimsskn Kne' samples and films of high Tc superconductors. -D. C. Mattis and J. Bardeen. Phys. Rev., m, 412 (1958). ' P. Knmd. O. Swln «K) J. Haferaur. J. .AfpL Pip..«. 22% (1974). = B. L. Watoo. B. Rosabfamaid F. Bndf=. ftii Her. Lac.n. 1047(1974). 3 K. W. Bktny. K. A. Molar. J. C. Badnorz. W. Badiags-. G. Amam. E Buluf|iu. MQ-3 A. Vnaid F. C. Matamu. Ptrs. Rer. B. 3*. 7241 (IW7I ' A M. Ports. K W Bkeev. K.A MoUaraod J. G. Bednorz Brvpiyy. im.S. FABRICATION AND MICROWAVE PROPERTIES OF Y-B»Co« 467 (19M). p, •'A M Pens K W Blanr.C. RossdlaadM Decntn. PtmaC. in {nut P. GKriomki, A. Kmopka, and S. J. tamdowki, InaBtote of Phyira. 'K. W. Blany.A.M. PoBisaidJ.G. Badaorx. SMI Site Caaaai..tS. 1153 Poliah Acadeny of Sdencea - We report cor atodie* of the interaction of II9M). 7 YBajCnjOr-T (VBCO) and BilCat&ViCaA (BCSCO) thin film, with mi- K. W Btoty. A. M. Poms. K. A. MoUxwad F. H Holnt>«j sotamffoc emmna. The film, ware ntyarnl en cabk ctocnu and aapphire aob- • A. M Paras aid K. W. Blaav. BbtpWaitd •traiea aaing a dmlopad aprwy-oo depoution todnicjiK. The teated (Um. 64 •ere abort Z - 3 |im thick, md exhibited [ood reperccretacting propertie* (e* *r YBCO Mm the 10 - 90 * tranition vrtdth w Z5 K. and the wo MQ-6 resistance w niched at 89 K}. Several teu itroctins bave been RELAXATION BEHAVIOR OF ULTRASONIC ATTENUATION IN YBa Cui0 . K. J. Sun*, and W. P. Winfree, NASA-Langley designed by spraying a mixbn of nitrate uteumii on a moderately 3 t Research Center; H-F. Xu. M. Levy and SImal K. Sarma, (-2*0*0 heated mbaJr»tethnm#iveiy thin metallic shsdow matks. Tie University of Ulsconsin-Milwaufcee. Kilwau^pe, VI 53201; H. film superciBTeDt dependence on millimeteMmvelength miuixmvi Cnton and R. Sel'd, Christopher Newport College. - Tetaper.itun> illunination ma imiMJi.il. and micnmavc detection and mixing expar- dependent ultrasonic attenuation measurements have been performed on a pressed powder sample of VB.ijCu3Or with imaita were perfinned. The pnaented experiments tamed ant to be a wny frequencies at 10, 27. and 32 MHz from 20K to 150K. An sensitive tool for studying Elm jraoalarity and the Dibit of intennin atcenuAtion tinomflly occurs at a teniperflturc close to the conoectionf. Oor studiei alao demonstrated that theae materiils can be superconducting transition temperature Tc (91K) for each frequency. The temperature of this anomaly shifts from below successftllly osed aa miUimeter-ndiatkii detectcn operatlanal at liquid Tc co above Tc fls"Cn e sound xircQuencv is increased from 20 MPi^ nitrogen tampentaara. to be exponentially dependent on temperature. The velocity *SDpported by the Poliah Government: Graota CPBR 15.6 and RPBP 01A increases with decreasing temperature, exhibiting a softening SAlao at the Department of Electrical Engiimring, The University of around Tc. These variations of attenuation and velocity at temperatures near Tc may be associated with the structural Rochester, Rocbeiter, New Yak 14627. distortion of icsnCu»0» ai^o Lndirectlv be i.nvo]ved witn MQ-4 SURFACE IMPEDANCE MEASUREMENTS ON HIGH Tc SLTERCONDUCTORS G.Miiller, D.J.Brauer, R.F-ujen, M.Hein, S.Klein, U.Klein*, H-Piel and L.Ponto, Bergische L'niversitat-Gesamthochschule Wuppertal, +Interatom GmbH - We have investigated Lhe rf properties of the oxide superconductors Y,Sa2Cu3O7_5 and Bi-Ca-Sr-Cu-0 between 65 Session P-4 Plenary IV CEBAF 8:15-9:30 a.m., Thursday, August 25, 1988 1O~ in. The operating temperature of the linac is 2K, based P-4 on a cost trade off between increasing rf heat loads with an CEBAF, A LARGE SCALE APPLICATION OF increase in temperature, end an increasing cost of refrigeration to SUPERCONDUCTING RF, A. K. Chargin, CEBAF - The decrease teinpentur" Coatmuouj Electron Beam Accelerator Facility (CEBAF) ii t 4 A pair of High Resolution Spectrometers in Hall A and a GeV, multipass, CW accelerator. The machine ii racetrack high acceptance, high energy electron spectrometer in Hall C will shaped with the linac split into two equsl parts located in the utilize superconducting dipoles and COB 29 qusdrupoivs The airtight aectioni. The recirculating magnets, which will guide Large Acceptance Spectrometer in Ha!! D is & six coil the beaXQ through four passes around the accelerating structure, superconducting toroid. are in the arc tedious connecting the two iinaea. At the end of the accelerator, the beam puiei into the switchyard where it is guided into any of three experimental end stations. The linac coniists of 418 Nb superconducting rf cavities operating at 1500 MHz to produce a high quality beam having a 'Work performed under Department of Energy Contract #DE- 100% duty cycle with an energy spread of 10~4 and emitt&nce of ACOS-84ER4O15O. Session EM Millimeter Wave Technology II 9:45 a.m.-noon, Thursday, August 25, 1988 of the SIS junction characteristics. We show thai noise is "squeezed" into one EM-1 quadrature under appropriate operating conditions. We determine the necessary DUAL CHANNEL I IS AND 230 6HZ SIS RECEIVERS IN experimental conditions to make 4 nearly noiseless measurement of the signal OPERATION AT THE OWENS VALLEY RADIO OBSERVATORY, by quadrature of the input radiation. D P Woody and R E Miller .Owens Valley Radio Observatory. Big Pine, CA The Owens Valley Millimeter Wave Interferometer Array 'M.J. Wengler and D.P. Woody, 1987, IEEE J. Quantum Electron., QE-23. 15 presently operating with dual channel 515 tunnel junction pp. 613-622. receivers The first channel covers the frequency range from 90 to 2M.F. Bocko, MJ. Wenglcr, and Z. Zhang, 1988, presented at ASC-88 (this 120 SHz and the second channel covers the freouency range from conference). 200 to 260 GHz The mixers consist of a corregated feedhom, single stage circular to rectangular waveguide transition, reduced "Partially supported by the Air Force Office of Scientific Research height waveguide with the 515 junction mounted across the E-plane and a non-contacting backshort The rm/er block has a EM-4 built-in RF choke for the IF signal path which is designed to Hi WAVE QUASIOPTICAL SIS HIXER5." Qlng Hu, C.A. Hears, present a snort circuit to the junction at frequencies adove the 2 P.L. Richards, Department of Physics, U.C. Berkeley, F.L. Lloyd, SHz IF frequency The SIS tunnel junctions are small area CIXI micron) PblnAu-native oxide-PbAu fabricated using a bridge tested tne performance of planar SIS mixers with log-periodic antennas at mm-wave frequencies from 90 to 300 GHz. The large liftoff technique The local oscillator power is provided by Gunn wHHC product (-10 at 90 GHz) of our Nb/Pb-In-Au junctions oscillators followed by doublers or triplers The receivers in the requires an integrated inductive tuning element' to resonate the 90 to 120 GHz band have a noise temperature of < I0OK, while the junction capacitance at the desired frequencies. We nave used two types of Integrated tuning elements, which were designed receivers in the 200 to 260 GHz band have noise temperatures in with the aid of measurements with a Fourier transform the range from 200 to 300 K. These dual channel receivers are spectrometer.* Preliminary results Indicate that the tuning mounted in 45 K closed cycle refrigerators They are in In parallel with a 5-junctton array gives a minimum mixer noise continuous use in the three element millimeter wavelength temperature of T15 K (DSfi) at 90 GHz with a FtfHM bandwidth of interferometer array 8 GHz. An open-ended mlcrostrip 3tub in parallel wltn a 3lngle 1. AT&T Bell Laboratories, Murray Hill, NJ 07974 Junction gives minimum mixer noise temperatures of 150 and 200 K (DS3) near 90 and 180 GHz with FWJK oandwldths of 5 and 3 GHz respectively. The relatively high mixer noise temperatures ooflipared to those of waveguido 3IS ni 1 xer s In a similar freouency EM-2 range are attributed ciainly to the losses in our optical system, OBSERVATION OF 4.2K EQUILIBRIUM NOISE SQUEEZING which is being improved, VIA A JOSEPHSON-PARAMETRIC AMPLIFIER, B. Yurke, P. G. Katninslcy and R. E. Miller, AT&T Bell Ubomories; E. A. Whittaker, • Supported by the U.S. Air Force OfTlce of Scientific Researcfi Stevens Institute of Technology; A. D. Smith, A. H. Silver and R. W, Simon, under Grant No. AFOSR 85-O23Q. 1 Li Xizhl. P.L. Richards, and F.L. Lloyd, "SIS Quaslparticle TRW - We have obicrved the squeezing of 4.2K thermal noise using a Mixers with Bow-Tle Antennas," Int. j. Infrared and Josephson-pmmetric amplifier operated in the degenerate mode at 19.5 GHz. Millimeter Waves, In press (1989). A 42% reduction in the equilibrium ooiie was observed. The amplifier has * Qlng Hu, C.A. Hears, P.L. Richards, and F.L. Lloyd, also been operated at O.IK with an excess noise of 0.28K referred to the "Measurement of Integrated Tuning Elements for SIS Miners with amplifier's input port This is leu than the vacuum fluctuationnois e hv/2k = a Fourier Transform Spectrometer," Int. J. Infrared ana 0.47K at the amplifier's input The amplifier thus has less noise than a linear Millimeter Waves, In press t!988). phase-insensitive amplifier such as a mtser could hive. At O.IK the amplifier has been openied in a nonchaotic mode with a gain of 12 dB. EM-5 JOSEPHSON TERAHERTZ LOCAL OSCILLATOR •. EM-3 R. P. Robertazzi and R. A. Bulirman, Cornell University W« BEATING THE QUANTUM LIMIT IN SIS MIXERS', M. J. have produced high critical current density, small arwi, trilaycr NbN/MgO/NbN tunnel junctions which have proven effective as local Wen^ler and M. F. Boclco, E. E. Dcpt., U. of Rochester - Analytic expressions 3 describing a potentially noiseless, two LO SIS mixer are presented. SIS oscillator sources in the Terahertz regime. In this experiment 4/irn NbN/MgO/NbN mesa junctions have been fabricated with good I- heterodyne receivers for millimeter and shorter wavelengths are capable of V characteristics with critical current densities up to 4 x 10*.4/c?n3, Adding little more noise to a detected signal than quantum mechanics requires, These junctions are capacitively coupled to Nb edge junctions which T\ — hv/2ks- The noise in high quality SIS mixers has been shown to be 1 are used as Joseplison detectors to determine the AC power level pro- completely amibutable to statisticsof the incoming radiation . A mixer pumped duced by the NbN oscillaloT. Our capacitive coupling scheme allows with two LO frequencies is sensitive to only one quadrature of the input signal us to couple — lnW of AC power into a 100 Q detector junction radiation. Quantum mechanics allows such a phase-sensitive detector to add 2 over the entire frequency range from 0.1 THz to 2.0 THz Correct- no noise. Using the theory developed fix the SIS 2LO mixer , we find simple ing for the impedance mismatch between oscillator and detector this analytic expreuions for 2LO mixer gain and noiie based on an idealized model corresponds to the AC pow^r at the NbN oscillator being in fxcnss 66 of 1 /ill'. We will describe the fabrication ami performance uf thw applications or as a materials diagnostic. We are building Jos*.'])hson junction TtTahrrtz oscillators and llu-ir application to tlir superconducting transmission fines with very thin films (t study of the behavior of Josephson junctions at and above the gap < X) for which the kinetic inductance dominates the eometrical inductance of the line. Various materials are sum frequency. We will also address the applicability of thu device for geing investigated. including Nb. amorphous use in integrated, broad band sub-millimeter wave detectors and for superconducting alloys, and the new high-Tc oxide far infrared spectrweopy. superconductors. The suitability of these materials tor practical applications, such as variable delay lines, is being examined and the relevant materials parameters (e.g., the magnetic ^penetration depth A and the effective •This research was sponsored by AF Contract Fl0G'2S-SG-Iv-OO34 with penetration depth X /t) are being established. To perform RADC funded by SDIO-IST. the measurements, the transmission line is treated as a microwave resonator so that its properties can be deduced from the resonant frequency and Q of the structure. We EM-6 shall report on the behavior of these structures as a function of temperature and frequency (1-20 GHz) and MATERIALS STUDIES FOR SUPERCONDUCTING relate these observations to the potential applications and NONLINEAR DELAY LINES.' S. M. Anlage. T. Hylton, H. J. physical properties of the superconductors. Snortland, S. Whitmore , and M. R. Beasley, Department of Applied Physics. Stanford University - The temperature and/or current dependence of the kinetic inductance of superconductors can be used to vary the propagation •Supported by the SDIO Contract F19628-87-K-00S0. characteristics (e.g., the phase velocity) of a Permanent address: Department of Physics.and superconducting transmission line, either far practical Astronomy, University of Oklahoma, Norman, OK 73019 Session MR High Tc Superconductors: Thin Films II 9:45 a.m.-noon, Thursday, August 25, 1988 sequential elactron-beaei evaporation of Bi and Cu —*»i» and MR-1 •ingle-ciyatal (StCa)o 5F2. Several sandwich layers of (SrCa) 5F , Bi, (srca) F , and cu ware deposited on yttria- PROPERTIES OF HIGH Tc SUPERCONDUCTING THIN 0 2 0 5 2 RLMS FABRICATED BY ELECTRON BEAM COEVAPORATION1, stabillzad ZrOj aubetrates. Itie filas were annealed at high N Missert, P. Rosenthal, B. Oh. S. Spielman, A. Marshall, R. teaperature, first in dry O2 and then in wet C^, then annealed Barton. M. R. Beasley. T. H. Geballe. R. H. Hammond. A. at 550^C and cooled to rocai temperature in dry ©2- The Kapitulnik", Stanford University - Thin films of resulting files, which were ~ In* thick, had enact temperatures Y-Ba-Cu-O and Si-Sr-Ca-Cu-0 have been grown by electron of - 85 K. Auger analysis shows that the Bi, ca, Sr, end Cu beam coevaporation from individual metal sources, concentration* are uniform throughout the thickness of the followed by a post-deposition, high temperature oxygon annealed fJOJ». Decent progress in Making files of the 110 K anneal. These films show a high degree of crystalline phase of BiSrCaCuO will also be reported. orientation, sharp resistive transitions and high critical currents. Recent work on thin films of Y-Ba-Cu-0 grown on SrTiOo substrates, using an ion beam to provide *This work was exported by the Department of the Air Force. activated oxygen during growth, has shown that the "123" crystal structure can be formed in-situ. Various techniques designed to enhance oxygen incorporation MR-5 in-situ - including ion beam activation, nigh Op pressure and post deposition low temperature heat treatments, have IMPROVEMENT OF AVERAGE FILM QUALITY IN been extended to thin films of Bi-Sr-Ca-Cu-O. Recent RBl,Cu3O7. SPUTTERED FILMS, R.W. Simon, C.E. Plan, K.P. results will be discussed. Daly, A.ET lie, and M.K. Wagner, TRW Space & Technology Group - Thin films of HB»,Cu3O7.x (R includes V, Er and Ndj have been deposited by four-gun RF magnetron sputtering from metallic targets in • Xe-Oj gas mixture and post-annealed in flowing O?. Substrates Include 5rTO3, sapphire and metal-buffered sapphire, Zrt>2, MgO and • Work supported by AFOSR. ONR. NSF. and NSF through the VAK)o. Four-point resistivity measurements show transitions as narrow Center for Materials Research at Stanford as 1K, whife magnetization and rf resistance measurements show •• Alfred P. Sloan Fellow, PYI more detail about wri quality. Composition is determined from EDX, RBS and ICP. Current density is measured, both with transport and magnetization measurements, and Is measured for microbridge MR-2 structures. Rms are further characterized by XRD and profiling by Growth and Properties of Sputtered Hich-Tc Oxide Thin SNMS, Auger and XPS. The films made from Er show grain sizes as Films. K. CHAR, M. R. HAHN, T. HYLTON, I. BOZOVIC, M. R. small as 20-30 nm. In addition, they have more compositional BEASLEY, T. H. GEBALLE and A. KAPITULNIK*, Stanford U." -- uniformity over the substrate, as well as lower normal state resistance. We have synthesized YBa2Cu3O7.t thin films of thicknesses 500 A Histograms show that the median .R*0 temperature may be as much to 6 Mm by reactive sputlering from three metal targets.1 The as 20 K higher for Er films as compared to Y films. We give some samples show sharp transitions (2 K width), low resistivities (100 suggestions as to why these particular rare earths show better jiftcm at 100 K) and high critical current densities (1 x 107 A/cm2 at superconducting properties over a wide range of stochkxnetric and 4.2 K). We will discuss the effects of the composition, thickness preparation conditions. and annealing process on the orientation of epitaxial thin films. We will also report results on other transport properties of the films with different orientations such as Hall coefficients, thermoelectric power and surface impedances. Optical properties MR-6 of the films will be presented and discussed. Preliminary results HIGH TEHPERATUXB SUM RCONDUC TING FILMS »T RF on Bi-Ca-Sr-Cu-O thin films will also be given. HAGTOTKOrt SPUTTERING, A.M. Kadln and P.H. Ballenllne. Dept. or Electrical Engineering-. University of Rochester, and J. Argana and R.C. • Alfred P. Sloan Fellow, PYI Rath. CVC Product*. Inc. - We have produced sputtered films ofY-Ba-Cu-O and BI-Sr-Cs-Cu-O, by rf magnetron sputtering front an oxide target "• Work supported by NSF under contract DMR-85I9753 consisting of loose reacted powder. Result* appear superior to rf diode I. K. Char, A. D. Kent, A. Kapitulnik, M. R. Beasley and T. H. sputtering from similar targets. Optimum YBCO flkns are deposited from a Geballe, Appl. Phys. Lett. 51,1370 (1987). •tolchlometrlc fl"-dlsmeter target onto a crystalline yttna-stabilized zlrconla • ubstrate heated to about 300 °C, and become superconducting after annealing In oxygen to 850 "C. Films exhibit zero resistance above 83 K, and MR-3 exhibit critical currents of order 1OO A/cm2 at 77 K and greater than 3000 A/cm2 at 4 K. nlms are essentially single-phase, randomly oriented 1-2-3 PULSED LASER DEPOSITION OF ORIENTED Bi-Sr-Ci-Cu-0 polycrystals. Systematic* of compositional and mlcrostructural THIN FILMS, D. K. Fork*. T. H. Gebtlte". J. B. Boyce. F. Ponce, R.I. uniformity and reproducibllity will be presented, together wiih Johnson, "Department of Applied Physics - Stanford University, Xerox measurements on thin-film mlcrobrldges patterned from the films. In Palo Alto Research Corporation - Oriented c-ixis films of Bi-Sr-Ca-Cu-O addition, Bi-Sr-Ca-Cu-O films have been deposited using a similar on <100> SrTiO3 have been fabricated using the pulsed excimer laser sputtering technique from a BiSrCaCujOjt powder target onto MgO evaporation technique. Deposition at room temperature in 1 rnTorr oxygen substrates, and preliminary results using a brief 860°C anneal gave a broad followed by an 875C anneal in oxygen yielded superconducting films with superconducting transition slrarUng at 85 K and going to ado at about 55 K. zero resistance at 77°K and a resistivity drop near 1 \0K hinting at the presence of another superconducting phase. Transmission electron microscopy shows thai the film is epitaxial with the substrate, with an abrupt and planar interface boundary. The observed films structure is MR-7 consistent with already published data. We arc currently working on LASER DEPOSITION OF QUALIFY HIGH mc SM?ER- growing superconducting films on other substrates. Initial results on Si3Nd CONDUCTOR FILMS, C. C. Chang, T. Venkatesan, E. w. substrates indicate lower resistance albeit semiconducting films. Chase, '/.. D. WU*, A. Inam*, and D. H. Hwang, Bell- Concurrently we have started growing oriented superconducting thin films core, ^Rutgers Univ. - Laser deposition of smooth of the Bi-Sr-Ca-Cu-O material on 1 mm fiberso f SrTiOj 1 roughness <10nm), crack-free, pseurto-crystalline films with TC up to 89K and Jc in the 10xE5Amp/sq.cm range on AI2O3 and SrTiOj have been MR-4 fabricated. The narrowest transition range is <1K SUPERCONDUCTING THIN FIt*B OF B^S^C^O^C^ WEE USING for film deposited near 650C which is supercon- SEQUENTIAL ELECTRON BEAM EVAPCRKTICM,* J. Steinbeck, DcK Air ducting at 89K without post-deposi tion annea1, Development Center, A. C. Andersen, and B.-Y. Tsaur, Lincoln Methods of obtai ning superconduct ing films at laboratory, Massachusetts Institute of Technology - Sif deposit ion temperatures below 5PPC, f ol lc««ed by ducting thin films of Bi^Sr^Ca^Oj^C^ have been aede by annea Is near 4 5OC have been fount!. These f ilms 67 are unique because they are ps^-udo crystalline, tiple superconduct ing layers with and without in- single phase, have no well defined grain boun- sulating and conduct ing buffer layers on Si have daries [which may explain some unusual diffusion also been made. 'Je discuss reasons for the h igh and Jc properties), and the epitaxial relationship film quality in spite of the low deposition tem- is determined by the substrate. Single and mul- peratures. Session LM Conductor Testing 9:45 a.m.-noon, Thursday, August 25, 1988 LM-1 applied load. We will discuss the implications of transverse load effects on cabled conductor Jc and the METHOD FOR CRITICAL CURRENT TESTING: SOFTWARE impact en the design of large CICC's for superconducting OCRRECTKKS, K. B. Siddall and D. B. Smothers, Iteladym Wteh fusion magnet applications. Chang Albany—Suparconducting critical current tasting software was developed which nakes four important iaprovaMnts in accuracy over that possible with analog test aquipunt: * This work was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National 1) Quasi steady state saaple current conditions are achieved Laboratory under Contract W-7405-Eng-48. by innH—anting savcie currant, followed by holding some milliseconds until the transient voltage decays before voltage sampling. 2) The aelf field correction frr* a helically wound mamplm is fTTiitert and subtracted fix* each saapled field reading. 3) A copper wire inductively wound shunt which is used for quench protection has a constant aeasured resistance fron LM-5 which the shunt leakage currant is ooeputed and subtracted FLUX CREEP IN A TEVATRON CABLE, M. Kuchmr and A. V. from the sasple currant by measuring the shunt voltage Tollestrupj F«mi National Accelerator Laboratory* - W« hava after eac*) sanple currat reading, Misurad tha slot Magnetization decay of i short sampl* (2.3 cm) 4) The critical current is recomputed froa a least squares ovar pariods of 12 to 24 hours. Tha spacial suscaptomatar usad curve fit to the power law: E - A*I~n whan the correlation for thasa naasura**nt* is based on a cowMrcial SQUID. Tha coefficient for the fit is high enough to ensure a better observed decay is logarithmic in time as expected from flux result than the raw datum. creep in the NbTi filaments. We ire nuking an attempt to correlate the magnitude of this dsciy with tha decay observed in Comparison with NBS standard Reference Material (tttfi) and the sextupole component of Tevatron dipole magnets and their current round robin ftojSn testing is examined. shorter prototypes. Flux creep in the filaments could explain the peculiar chromaticity behaviour discovered in the Fermi lab LM-2 superconducting synchrotron. Measurements with the sample in an environment providing a closer simulation of the conditions in a THE ALUMINUM STABILIZED tfb-Tl CONDUCTOR FOR THE ZEUS THIN Magnet *re being planned. The understanding of this phenomenon SOLENOID, R. Bruzzese, S. Cereaora*. G. Donati*. S. Rossi*, N. may ba instrumental in guiding the search for efficient SacchettI, H. Spadoni, Assoclazlonc EURATON-ENEA sulla Fualone, superconducting synchrotron operational procedures. Centro Rlcerche Energja FraBcatt, C.P. 65. 00044 FrascatI, Rene, Italy - The ZEUS experlatnt, a huge experlnental apparatus for high energy phyaics to be Installed on the hadron • Operated by Universities Research Association, Inc., under electron ring accelerator HERA at DESY-Ranburg, vill use a contract with the U.S. Department of Energy. superconducting thin solenoid surrounding a nuaber of Important particle detectors. The essential features of this magnet are 1.8 T magnetic field on the axis, 2.3 T aax. field on the conductor, Inner dlaeeter 2 n and solenoid length of 2.5 a. As physics requirements ask for a total solenoid thickness lower than 0.9 radiation length, a conductor consisting of a LM-6 Rutherford type tib-Tl cable cladded with high purity aluainun SELF FIELD EFFECTS ON THE SUPERCONDUCTING TO NORMAL has been developed. In the present paper we will report about TRANSITION Of S/C CABLES, P.Fabbrlcatore, PFemandes. R.Parodl characterization of a conductor to be used In this particular and R Vaccarone, I.N.F.N. Sezlone dl GENOVA - The onset of kind of magnet. Data on critical current, transfer length and the transition of a S/C cable to the normal state Is well residual resistivity ratio will be given and discussed in connection also with the Influence that the various fabrication described by the relation V - V^"*" where V is the voltage steps can have upon then. The final conclusion Is that, using a dropper unit lenght, Vc the critical one, I the reduced current high critical current density base strand (2,030 A/an at 6.5 T and 4.2 K), a reliable conductor has been developed meeting the J- dt Is the critical current), n is an Integer ranging from 10 to 40 c Europa Hetalll-LMI, FornacI dl Barga, Lucca, Italy depending on the cable quality. A correct evaluation of the critical current and n-value must take Into account the effects due to the LM-3 self field or the cable For high current cable the self field can TRAINING IN SHORT SAMPLES OF SUPERCONDUCTING affects the measurement for * 10 -s- 15% In the present work a CABLES FOR ACCELERATOR MAGNETS, * A. K. Ghosh. K. Carber. theoretical model Is developped and it Is applied at the results K. E. Robins and V. B. Sampson. Brookhaven National obtained in the critical current measurements of S/C cables for high current NbTi cab'les, the samples have to be "train- HERA dlpoles, actually performed at I.N.F.N. in Genoa It is found that ed" by repeated quenching In order to obtain a reasonable the critical current and the n-value are strongly dependent on the voltage-current plot. This "training" behavior Is most pronounced when the applied field Is perpendicular to the self field Measurements, on the same cable, performed in different wide face of the conductor. In this configuration, the set-ups are compared degree of training was found to be strongly dependent on sure. Data will be given for SSC and RHIC prototype ca- support this conclusion. Results of the "training" ex- periments will be analysed in the light of conventional stability theory. LM-7 CHARGE AND DISCHARGE OP LOU HEAT LEAK MAGNET SYSTEMS, M. K. Abdelsalam and M. A. HUal, Applied Superconductivity dlscharlng low heat leak magnet systems are presented. In the * Work performed under the auspices of the I! S Depart- B«nt of Energy. first scheme >i flux punp charges the magnet and detachable leads are used for discharge. The flux purap Is kept at 16 K LM-4 standby. This scheme Is especially attractive for space applications where magnet charge can be cxtreraely slou. The THE EFFECT OF TRANSVERSE LOAD ON THE CRITICAL lead losses can be significantly reduced it nee the flux nunp CURRENT OF NbaSn CABLE-IN-CONDUIT CONDUCTORS.* Current can oe several orders of fsaffnltude 1 e&& than n*ii?ie t L.T. Summers and J.H. Miller, Lawrence Livermore National the second scheme for both charging and discharging. These Laboratory - We have investigated the effects of transverse leads consist of a single layer superconductive helical load on the critical current of cabled superconducting wires. winding and a high purity normal section. A transition disc Measurements have been made using simulated Cable-In - Conduit Conductors (CICC) with helium void fractions in the leads. The temperature of this disc is kept below the range of 25-40%. The transverse load effect is shown to be temperature during standby. This reduces the standby heat a function of the helium void fraction, with higher void leak to 12 of that of regular optimized leads. Analysis of fractions giving rise to an increased sensitivity of Jc to 68 Session EN Josephson Junction Dynamics 9:45 a.m.-noon, Thursday, August 25, 1988 harmonic and sub~har«onic steps in the characteristic, and with EN-1 suitable values of Junction capacitance, drive level and drive frequency, substantial parts of the characteristic fom a PICOSECOND SWITCHING DYNAMICS OP A devil's staircase. These are associated with localized regions JOSEPHSON TUNNEL JUNCTION,* D.R. Dykair, R. which are clearly chaotic. The effect of different levels of Sobolewski," and T.Y. Hsiang, The University of Rochester - We noise on these features has also been studied systematically. have modeled our previously reported switching measurements of a He point out that this electronic analog produces detailed Josephson tunnel junction excited by photogenerated- picosecond- 1 characteristics very quickly, compared with solving the current pulses. The junction was found to be switching from the junction equations numerically. Thi* allows the conditions zero- to the finite-voltageregim e for subcriticzl current pulses. This needed to observe chaotic behavior to be determined easily, and study shows that in addition to pulse charge, pulse rise time is a trends in the data to be established rapidly. We have also critical parameter in determining the junction response. Simulations combined two identical junction analogs and noise sources to were performed using Gaussian psJses to simulate the experimentally model a DC SQUID, and. preliminary results will be given for measured waveform. Significant deviations from the dc switching this system. threshold behavior were found for pulse rise times up to 5 ps. Pulse rise time is in fact the parameter which causes the onset of the observed chaos in these devices.2 Pulse fall time was shown to have no effect, which is consistent with the critical rise time interpretation. *Work supported by the Air Force Office of Scientific Research EN-5 (F49620-87-C-OO16), Laboratory for Laser Energetics and bv NSF (DMR-85-O6689). DYNAMIC STABILIZATION OF A MICROWAVE DRIVEN •• Permanent address : Institute of Physics, Polish Academy of JOSEPHSON TUNNEL JUNCTION AGAINST A PERIOD-DOUBLING Sciences, Pl-02668, Warszawa, Poland. BIFURCATION*) . J. Bindslcv Hansen, G. Friis Eiikscn, M.R. Sarnuri- 'DJJ. Dykaar, T.Y. Hsiang, and G.A. Mourou, IEEE Trans. Magn. scn, and H. Svensmaik**) , Physics Lab. I, The Technical University of MAG-23, 767 (1987). Denmaric, DK-2800 Lyngby, Denmaik. We have investigated the dynami- 2R. Sobolewski, D.R. Dykaar, T.Y. Hsiang, C. Vanneste. and C- cal stabilisation of a driven non-linear system, like a microwave driven C. Chi, Physical Review Bl, Vol.31 (3778) 1988. Josephson tunnel junction, against an incipient period-doubling bifurcation by a small periodic perturbation. Though somewhat counterintuitive, this stabilisation is most effective when the perturbation has a frequency close EN-2 to the frequency of the half-harmonic signal generated by the period- doubling bifurcation. Another property of the period-doubling bifurcation NOISE CHARACTERISTICS AND INSTABILITIES OF LONG is its ability to amplify perturbations. We here present a simple, general JOSEPHSON JUNCTIONS, * B. S. Han, B. Lee, 0. C. Sy«ko, V. theory of thisc phenomena and show how it applies to the case of a small J. Yeh and D. J. Zheng, Dept. of Physics, University of Josephson tunnel junction. New experimental data for Nb/NbOx/Pb junc- Utah, Salt Lake City, Utah 84112. - Because long Josephson tions are presentet and compared with numerical calculations based on the junctions have many applications to digital *nd analog theory. An improved understanding of thise phenomena in microwave circuits, we have investigated their noise characteristics driven tunnel junctions may shed iight on ihe problem of the observed and Instabilities that occur at certain bias conditions. excess noise ("noise rise") observed in Josephson parametric amplifiers. Results are presented on Nb-Al2O3-Nb Junctions, of the overlap type, with current densities ranging froa 0.2x10 to 7x10 anperes/cn ; the junction dinensions are 130 tm *) Supported in pan by the Danish Natural Science Research Council. long and 6 pn wide. Low frequency noise was Measured In **) Present address: Dept. of Physics, University of California, Berkeley, zero magnetic field in Junctions biased near Che critical current in tfiB zero volcacQ state • Our rent flue tua t ions caused the junctions to switch to che nearest available state. In a magnetic field, the junctions were biased at self-induced current steps due to fluxon action, and switching was observed between the bistable states of the fluxon. This was caused by thermal fluctuations at 4K. EN-6 Finally, additional noise was aeasured at a few of the subharnortlc steps which were observable for Junctions MUTUAL LOCKING, CHAOS AND DEVILS which were not heavily daaped. In fact neasurenents were STAIRCASE OBSERVED IN TWO JOSEPHSON TUNNEL on Junctions whose McCuaber parameter nuaber 0 ranged JUNCTIONS WITH A COMMON RESISTIVE SHUNT from 200 to 20. As the damping increased, the * H.D.Jensen, A.Larsen, and J.Mygind, Danish Institute of Fundamental instabilities were reduced In agreement with existing Metrology, and M.T.Lcvinsen, University of Copenhagen. models. We have studied the phase-locking in a pair of individually biased, resis- •Supported by U.S. Air Force Grant. AFOSR-86-0020. tively and capacitively shunted JosephBon junclions, coupled by a com- mon resistive shunt, on an analog computer. Under certain conditions locking is found to occur at all rational frequency ratios. A critical line EN-3 is found in parameter space along which the steps form a complete devils CHAOS AND CATASTROPHES NEAR THE PLASMA FRE- staircase having a fractal dimenajo:* of 0.87. Beyond the critical line bi- QUENCY IN THE RF-BIASED JOSEPHSON JUNCTION. H. I. Kaulz, furcations occur on all Bteps following the Feigenbaum sequence to chaos. National Bureau of Standards mid R. Monaco, Istituto di C'ibcrnelica. The Feigenbaum constants are recovered to a fair accuracy. The study is Elrinenliiry llirory predicts a stability rrgimi for the zero-voltage stale of being extended to include also reactive coupling networks. The results are an rf-l.iasrd JtucpJiu.n junction givm by id( < \J0(hf\U wherr idc and compared to experiments with two Joscphson tunnel junctions shunted on i,l nrr the normalized dr- and rf-bias amplitude* nnr) Jo is the zero-order Mess?! function. The Bcssel-fiiuction approximation is acrnrft.tr for bias the chip by a gold film. 1 ir< o>tienrie<; u.-rf mticli Rrrairr tlmn tlir plasma frequrncy urp but numerical simulations based on the Slrwarl-MrC'uiuber model reveal that near the plasma frec|tiency Hie stability pattern changes to include regions where • Supported by the Danish Research Academy, the Danish National both riiaolir instabilities and cusp catastrophes are found. The onset of Council of Metrology, the Danish Natural Science Research Council and chaos pr-irliirrR stability holes in the loh-s of the Bessel-function pattern the Commision of the European Communities. that di-vrlop through a jirriod-doubtiiiR scenario. With decreasing rf frr- qiiency, |>eriorl-2 behavior occurs first for u'rf between 1 -Rwp and 2.0u;p and the onset of rhnos urrtirs for -jrf bet wren I Xi*p and I .Su>p. The resulting chaotic instabililifs give risr lu holes in ihr stability region of the zero- voltage state in the i,i,-i,r plane that hnvf been verified experimenlally in -liobtimi/leftd-hisinulh junctions. Cusp catastrophes occur not in the EN-7 lobes of ihe Bessel-ftnidioii pattern but near Hie zrros of ./0 where the ACCURATE OSCILLATION MODE ANALYSIS IN THE JOSEPHSON zero-voltage stat*- if fjtpecled to Itavp zero dr-l-ias range. Simulations re- JUNCTION CIRCUITS, K.Araki, K.Aklyama, and M.Morisue, Saitama University — We have analyzed and simulated oscillation modes ,--=1 tl,n| !)•-th>e 69 inlacot bf CIC observatjon of osillation wave stabl* m-2 ir istence range ol oscillallon EN-8 EXPERIMENTAL RESULTS ON THE METASTABLE STATES IN JOSEPHSON JUNCTIONS, R. Crisliano, S. Pagano and P. Silvestrini, Istituto di Cibernclica CNR, Arco Felice. Italy - Josephson Junctions exhibit several meiastable states in the I-V characteristic. The understanding of the decay of such states in the presence of noise has noiiceable interest in view of devices applications. We report experimental results on the metastabiiity of both the V = 0 and the V / 0 states. A comparative analysis of both the decay mechanisms at various values of the Josephson coupling endgy allows to obtain useful informations on the relevant parameters in the lifetime of the V jt o state. In particular we have investigated cases where the lifetime of V = 0 state is comparable with the lifetime of the V ^ 0 state. This situation is experimentally realized by applying an appropriate external magnetic field. The modifications of the I-V characteristics in such a situation are reported. A similar picture is also observed in the switching dynamics of the other current singularities in the 1-V characteristics as Zero Field and Fiske steps. The effect of noise on such structures is discussed in connection with the decay dynamics of the Josephson current. EN-9 A NEW METHOD FOR THE INVESTIGATION OF JOSEPHSOH JUNCTION CIRCUITS, N.F. Pedersen, Physics Laboratory 1, Technical University of Denmark, DK-2B00 Lyngby, Denmark. and A. Davidson, IBM T.J. Watson Research Center, Yorktown Heights,, NY 10598, USA.- A Josephson junction circuit may r«Ut.lon bctvcen 6t an* WUlr, contain several solutions with different qualitative behaviour giving rise to for example hysteresis in the current - voltage characteristic- In particular, a junction imbedded in often determined by intt? rrni 11 ency be t we on two nearby J>CT" IOQIC or chaotic solutions. Hence knowledge of the global behaviour oi a nonlinoar system is of great, importance for the practical appi ications. we present a now scheme based on the ce. 11 ^to—cre 11 napping technique for the estimation of the full global behaviour of a Josephson junction circuit. With this scheme we find a 1 j the different solutions, their geography in the phase space, and their character (whether they are periodic EN-10 STRUCTURE OF RESISTIVE NETWORKS FOR DISPERSIVE TUNNEL PROCESSES, H. Liibbig, Phys.-Techn.Bundesanstalt (PTB) Berlin, G. Brunk and Ch. Zurbrtigg Techn.Univ.Berlin. - We discuss fundamental construction principles for equivalent circuits of superconduction pair- and quasiparticle tunnel junctions for the purpose of technical applications. - To lowest order of microscopic tunneling the two basic features of the corresponding macroscopic dynamics (exp i if>/2 non-quantized state variable): the energy neutral self-coupling of the litlon betveen 6c and Ic/Imln quantum phase, V, and the energy effective admittance, will be represented by the equivalent two-subcircuit-network. 70 Original dispersion relations of different junction types, and appropriate model-circuits consisting of classical elements EN-13 (including their temperature dependence) will be discussed in detail analytically, fts a main result it will be argued that DC VOLMlit ;U LIIPLlC'iTJ.1: A NOVEL APPLICA- for all types of dynamical processes the tunnel conductivity TION Or P.JASE LOCKING IN JOS! PHSOrJ JUHCU0H AttRAYS, acts like a high-pass-damping; for low-frequency excitations - Hecen tl ;• , a circuit for precise multiplication of the nonlinear self-coupling provides the mapping on the dc (or If) voltage based on qu ANOMALOUS SWITCHING DISTRIBUTIONS IN ULTRA-LOW DISSIPATION JOSEPHSON JUNCTIONS. C. D. Tttcbe. J. R Kirtky, W. I. Gallaiher, A. W. Kieinnuer. R. L. Stodstrom. S. I. Raider, B Bumble. IBM Research Diviiion, T. J. Wataon Rcaetrcb Center - AD extensive Literature «x- 1. Y.K.Semenov, Mu1tI - Oosephson - Junction Structu- isls on the distribution of critical current* observed when a Joeephaoo junction res for OC Voltage Multiplication, In: Lxtended is twitched from below threshold into the voltage state. Understanding of this Abslr. of ISEC'57, Japan, Tokyo, Aug. 1967, effect is important for digital applications of Jowphson junctions and for fun- pp. U6-140. damental investigations into macroscopic quantum effects. However, previous investigationi have focused on junctions with appreciable shuot conductance below the gap voltasje. We report here on measurements of switching charac- teristics of unusually high quality Nb-PbAuIn edge junctions. The resistance EN-14 measured from the junction IV characteristics below the Pb gap were in ex«as SINGLE-ELECTRON TUNNEL JUNCTION ARRAY: A(J of 10 MOhnu it temperatures below IK. Switching characteristics were ELECTROSTATIC ANALOG Of THt JOSEPHSON TRANSMISSION measured for junctions with two very dissimilar current densities, 0.2 A/cm1 LINE, k. K. Likharev, H. S. Bakhvalov, C. S. Kaza- and 2000 A/cm1, corresponding to critical currents of approximately ISnA and cha, and S, I, Serdyukova. Joint Institute of Nucle- 30*iA respectively. In addition, characteristics were measured for a junction ar Research, Oubna, and Moscow State University -- Ke have carried out a detailed analysis of statics which had substantial sub-gap conductance with a resultant critical current of about SOOpA. This junction had switching distributions that agreed well with Junctions exhibiting the correlated single-electron standard thermal activation theory. This junction was measured in parallel with tunneling.1 This phenomenon results in behavior of the low dissipation junctions u t check on the noise properties of the system. the array which Is qualitatively similar to that of The non-shorted, 30>iA junctions bad nearly temperature Independent switch- the Josephson transmission line. In particular, ex- ing distributions for temperatures between 0.4SK and 6.0K. The width of the ternal electrie fields applied to the edges of the distributions were broader than expected from the predicted thermal activation array can Inject single-electron charged solitons distributions for a low dissipation junction. The 15nA junctions had switching into the array Interior. Interaction of the soli tons distributions that were also approximately independent of temperature above with each other and with the array edges Is very si- 2K. but with widths which were narrower than expected from the standard milar to that of the Joseph son vortices (sine-Gordon model. At low temperatures ( below l.SK } the observed widths of the 30nA solitonsj in the Josephson transmission line. Under junctions increased dramatically. certain conditions, a coherent motion of the sollton train along the array Is possible, with generation of narrowband oscillations of frequency f=I/e where 1 is the dc current flowing along the array. This process, qualitatively similar to the Josephson os- cillations, is however quantitatively different: even EN-12 at T+0 It Is statistical rather than dynamical. In our report. Impact of this peculiarity on properties DYNAMICAL STUDY Of THC SUPERCONDUCTING PHASE TRANSITION of the arrays, as well as possible applications of OF TWO DIMENSIONAL NETWORKS, 8, Jeanneret, Ph. fltickiger, Ch. the arrays In supercon duct Ing electronics, will be Leewann and P. Martinoli, Institut de Physique, University de discussed In detail. Neuchfttel, CH-200Q Neuchfttel - The superconducting phase tran- sition of square aluminum networks was studied by Measuring their complex sheet conductance with a two coil mutual induc- 1. K, K. Likharev. IBM 3. Res. Develop. 12, IHU tance technique. Such artificially prepared networks are parti- (1966). cularly well suited for the understanding of the granular beha- vior of the high Tc ceramics, currently modeled ss two dimen- sional, weakly site disordered arrays of Josephson junctions. Below the mean field transition, the observed jump in the su- perfluid density (proportional to the imaginary part of the EN-15 conductance) together with its frequency dependence, has been •nalized in the Framework of the Kosterlitz-Thouleaa theory. As a function of perpendicular magnetic field, the ac-response of MU1/TI-FLUXON DYNAMICS IN IKHOMOGENE- the networks exhibits a complex oscillatory behavior, the fun- OUS JOSEPHSON JUNCTIONS: EXPERIMENT, A] exey damental periodicity corresponding to changes of one flux quan- V.Ustinov, Institute of Solid State Physics, USSR Aca- tum per unit cell of the array. In strongly coupled networks demy ol Sciences - Long Josephson junctions Nb-NbOx- (normal state strip resistance Rs - 10 Q) up to 50 such os- -Pb with artificially formed SiO i nhomogenei t i es in 1ho cillations were observed. As Rs is increased the strip width insulator 1 nyer have been studied. A fine structure has becomes larger than the coherence length and the vortices have been observed on the current-voltage characteristics o( to nucleate a normal core in order to cross a strip. This nu- the junctions. Such structure predicted in Ref. (J) is cleation process reduces the vortex mobility causing the oscil- considered to be due to the resonance interaction bet- lations to disappear when Rs j> 10 Q. ween the f luxon and it s radiati on. Singl e-f luxon effect in zero magnetic f i eld and mu] ti-f I uxon effect in large (i el d have boon st udi ed expert mental 1 y. The resul t s ore compared with those of the perturbation theory and the numerical si mulat i on. A multi-f 1 uxon pinning elf ect ob- served on the commensurab] e I atli ce of i nhomogeneiti es i s report ed and di scussed. (l) A.A.Goiubov, A.V.Ustinov, IEEE Trons.Magn. 23 (1987) 781. Session MS High Tc Superconductors: Thin Films III 9:45 a.m.-noon, Thursday, August 25, 1988 MS-1 EPITAXIAL FEATURE OP YEaCuO TrH.ll FILMS PRE- electron beam source. The deposited multilayer films PARED EY MULTILAYER DEPOSITION, S.Z.Wang, Z.L.Bao, of YjO BaO and Cu became uniform superconducting S.L.Wang, *l.Y.Ye, G.Li, C.Y.LI, D.L.Yin, Dept. of thin films with a zero resistance temperature of Physics, TeV.inf University, PR China - YBaCuO thin above 80 K after three steps of heat treatment, uni- films have been prepared on (lOO)SrTiO^ subFtrate fying at low temperature, forming phase at high tem- by multilayer deposition technique using a single perature and ajusting oxygen content. The epitaxial 71 growth with a-axls n6raal to the film plane was con- fined toy x-ray diffraction. The result suggests that It Is possible to prepare epitaxlally growing XBaCuO thin tilmm using any technique which can ob- tain the aixiture of three oxides of Y,Ba and Cu before forming a. crystalline phase. The epitaxial filMB are characterized by electromagnetic measure- ment, SEM, RBS and RHEED, and the results are re- ported. MS-2 INVESTIGATION ON THE MEW SYSTEM OF Bi-Sr-Oa- pjg. 1 X-ray diffraction patterns On CSCIDE SnPERCOKDOCTIKG THIH FILMS, B.B.Jle, S.I. of annealed specimens. Ta denotes Fig.2 Relationship between Tc and Wang, Z.l.Bao, P.R.Wans, O.Y.Li, G.Id., S.Z.Wang, B. the annealing te«pertature. The chenical shift of Bi(Af). Tc upper pattern indicates the film denotes the zero resistance tenpe- L.Yin, Dept. of Physics, Felting University, PR China is nearly single-phased and the rature. Specimens were prepared - Bl-Sj>Oa-Ou-0 superconducting thin films with a grain orients preferencially to by varying the Ta. (OOt) direction. •ero resistance tenperature of 80 K have been prepa- red by a nultllayer deposition and diffusion method. Its nominal conposltlon is BiSrOaOugO . Energy-dls- perslve x-ray analysis display that the composition T*-840'C distribution is nonunlform along the film plane. X- ray diffraction results Indicate that Its crystal- line structure is sane with that of the bulk mate- / eso rial. The superconductivity of the thin films le sensitive on Sr/C» ratio and heat treatment tempera- ture, but not sensltlre cm heat treatment atmosphere. The «e«»ure«eot results of superconducting critical characteristics of the thin films are reported and coapsred with that of IBaCuO thin films. 60 100 150 200 250 3Q0 TEMPERATURE ( K ) MS-3 ANNEALING TIME (nun) SUPERCONDUCTING CHARACTERISTICS OF VBCO FILMS, Kazuo Pig.3 Tc vs annealing tine. The Mukae, Michihite Huroi, Toshiyuki Hatsui, Yuji Koinuna, Koichi Fig.4 Film resistance against the figure reveals a clear dependence aeasureneni temperature. Both Tsuda and Megumi Nagano, Fuji Electric Corporate R & D Ltd., of Tc on the substrate Materials. Japan - High Tc VBa Cu.O (YBCO) ttun films were • ivestigattxj. filas were annealed at 840% for The DO f i lms were prepared in two synthetic processes of rf~ 20 mn. pianeir Rugnctroti sputtGfxn'j* ' A ) depoiiL t ton at low tcn*jier without post-annealin*". SrTiO and HgO Single crystals were used as substrates. The critical temperaturetTc) of VBCO Iilms MS-5 prepared in process(a) depended on film thickness and substrate material. The microscopic island structure of the thinner filma PREPARATION OF ¥-Ba-Cu-0 FILHS BY EVAPORATIHG THE cAvised lower Tc« Furttieri^or^g Auger electron Qnc)lysi£3 revisaXed THREE ELEMENTS USING RESISTIVE HEATING, A. Nakaytu, N. Ochi, K. Takeuchi*, H, Ito and Y. 01caba\ Univeraity of that Sr and Ti atoms diffused into YBCO films by the post- KwrngM*, Uni-vanity of Tokyo , - Y-Ba-Cu-0 thin filaa contrast , no Mo, atoms were detected in the VBCO f1lms on MgO uawa fabrlcatad by «vapor*tinj the throe «le»enta using substrate. This fact explains tne difficulty to produce raviativs heating. Thrae W boats wore used in order to submicron superconducting film on SrTiO. in process(a), Although deposit the setal layers, Cu, 8a and 1 in a conventional oil as-deposited YBCO films prepared in proct-sslb) formed YBa_Cu 0 diffusion vaeuua syataa. In this nthod ccntrolabUity of crystal, they did not show high Tc. However, post-annealing at •ol ratio (X:B»:Cu) of I-Si-Cu-O fll«« is excellent. ^5O*"Q5O C gavG h voher Tc a^ trie* annea ling temper at ure increased. Subltratea we used were SrTIO? (100). The depoaition rate vai 0,2-0J5 na/a and the background praiaure wta better thin 1 x 10 "^ P*. Th« source aatariala were pure aetal Y, Be, Cu. A layer of Cu wai flrat evaporated, followed by layers was 6000A/cm -at 77K. of Ba and T. Thi* evaporation sequence was repeated 6 tiaes, and nuaber of total layers was 18 layers. The top layer was Y , bacauee 0a. easily reacts with hualdity in ataoaphere. In order to fora the euperconducting phtae, the aeUl filaa ware ajmealed in flowing Op £*• at 900'C for 30 MS-4 sin* and then cooled to 300 C at a rate of 2 C/iin. Reeiativity of the obUln*d fiUs at 300 Y. VM ftbout 2 iici CHDfl-PHYSICAL DIAGNOSIS OF HiSrCaCaO THIN FILM PREPARA- and the reeistivity wae linearly decreaaed with teaperature TION, T. Kofeayaahi, Y. FsJoawto, *H. Hidaka and H. Toooochi, decreaeing. Tc(oneet) VII about 88 K and Tc(tnd) wee 65 K. Faculty of EafiBttriaj Scitnct, Osaka l/nivtrsity - The present Hoi ratio of YtBaiCu of the obtained fill was 1:2.18:3,09 work dtaoMtratii the aaoealinf effect on BiSrCaCup thin files using inductively coupled plasaa analysis. fro* cbeancal aod physical vitw points. Ill addition to the •Metrical MasurMMats, tha spntttr-depositad filu wtrc chara- ctarizad systaaatically by ESCA, X-ray diffractioa, EPWA, ud so on. A rtry narrow ta^cratur* raaf* (^0 ± 5'C) was allotted to the filM aaaaalinc, above aad below which the superconductivity sifsificaatly degraded. Alpoit ainfle-phastd polycrystalline MS-6 BiSrCaCafi filat, haviu the caxii orieacation, was obtained at the taaperature of 540 "C. However, it was a low Tc phase (Tc— YBCO THIN FILHS PREPARED BY MOCVD,* L.H. Jtie, C.R. B a I, 76 K). The valve of Tc increased with incrtaiinj the bindinc T.2. Shen, J. Nt, *nd T. W«i, Shanghai Institute of Metallurgy, •Mrp1 of Bi (Af) op to 158.2 eV. With further increase in the Acadtnld Slnica — We have used the setal organic compound bindinc enersr, Tc resulted in an abrupt drop. ID the cxtrene vapor sources (HO), supplied by the organic•Iniiitutt of case where the energy MU ssy 156.6 eV, no sign of superco- Academis Sinica, to prepare high Tc supperconducting thin film nductivity was SMO. A selection of the substrate Material wis by CVD Method. Two systems have been designed for this purpose. the aanthar key to provide the high Tc film. Among many crystal One system with three pipes each carrying (Y, BA and Cu) sources and ceramic candidates, sn HgO single crystal appeared to be the vapor, carried by O2 or Nj, injel into the heat deposition aost favorable one. At the conference, the details of the above chamber, where the substrate (ZrO? or SrTiO3> were lying. and additional topics concernioi the high Tc phase will be After the deposition the samples can be drawn into A h^Bt given. treatment chamber, where heat and oxygen are supplied to form the desired SC phase. The oilier system has a plasma excitation * TOSOH Inc., Kanagawa, Japan 72 Characteristic variations in resistivity under diffe- rent experimental conditions (asong others gas pres- MS-7 sure (oxygen or inert gases) and rate of tesperature HIGH Tc 5UPERC0KDUCTIKG THIH FIUS PREFAMB BT FLASH chanffoj ar$ related to licroObrucviiril cnangee SQQ EVAPORATION, T. Hitou. Y. Tsksl. and H. Ivilun, «snyi corresponding superconducting properties. University - uuperconductlnc thin fills or Y-ls-Cu-0 mi 11-Cs- Sr-Cu-0 oxides «cre prepared by • sliple techRlqiM or flash /I/ A.Davidson et al., Appl. Phys. Lett. 52(157)1988. evaporation. Flash evaporation Is the aethod to svsporiM aultl- eleients with different evaporation tnpariturwi iHtutly. This aethod Is effective for the preparation of th« high Tc superconducting thin fllia eapeclaly, ones wltlt aaltl- eleaenta.auch as r-Ba-Cu-0 and Bi-Ca-Sr-Ou-0. F1«« powder of Y- Ba-Cu-0 and 81-Ca-Sr-Cu-o superconductlnc oxides ware prepared MS-11 by the conventional solid reaction of Y,0,, BaCO,. 11-0,, A SIMPLE METHOD FOR PREPARING CaCOj. SrCO,. and CuO. 2 3 SUPERCONDUCTING HIGH Tc THIN FILMS, P.ROraano, The stolchloaetrlc alxturea of these stsrtlni aattrlals A.Nigro, R.Vagiio, Dipartincnto di Fieica, (Y:Ba:Cu-l:2:3. Bl:C«:Sr:Cu-l:l:l:1.4) were calcined at J«O»C Univsraita' di Salerno, Italy, E.Signoralli, ITH, for 5 hours and 880"c for 20 alnutes respectively. T)w reacted C.N.R., ciniullo Balsano, Italy, and K.E.Gray, products MS-13 BOUNDARY LAYERS OF OXIDE SUPERCONDUCTORS FILMS PASTED ON *!,(),,SrTiO, and VSZ . K.ftcalsuaa.T.Ohara.K.Kaiho and H.Tateishi, Elcclrotechnical Laboratory. Since the discovery of the ne« hieh Tc superconductors there has been considerable progress in produced semiconducting films. Superconducting films were the production of thin filas of these nen iatcrials, YBCO and obtained after the second heat treatment at 850-870 C for 3 minutes. The powder «-ray pattern showed a muHiphased system. BSCCO above liquid nitrogen leaperaturc. All reported successful This paper will compare the results of these films to others thin fila growth techniques of VBCO have required a siinificanl made on different substrate materials and buffer layers. Post^crowith Qjiy£^'^ anneal IFIK cycle to lora tno superconductin£ phase of ceramic systei. In this paper the influence of these anneal inn c.yclr to the substrates or wafers and also to YBCO and BSCCO ceraaic superconducting filas has been investigated by MS-10 using energy-dispersive X-ray analysis ( EDX) and scanning RESISTIVITY BEHAVIOR DURING ANNEAL OP electron aicroacopy (SEN) ennainalions. To enhance these influe- YBa-Cu_Q» FILMS, A.Hohler, H.Neeb, and C.Heldan, nce, relatively thin YBCO and RSCCO pasted fills on the wafers Institfit fftar Angew. Physlk, Juatus-Lieblg-Onlv.Giea- have been chosen. The TCBUUS shov that there is a the boundary sen, D63OO Gieaaan.P.R.G. - Using a technique similar Inyer of the intenndiate product!) (thin boundary layers) «hich to Davidson et al. /!/ the resistivity behavior of sputtered rBa.Cu-O- Cllma ha« bean investigated du- consists oT Ba compounds (Ha Kl oiid<> on A!jn,,ao Zr oxide on Y ring anneal at t9«pe?atures up to 920 C with ths ala BX st.ibiti7ed Zr (YSZ) and Ra Ti oxidr on SrTiO,.) belnr-en of optimising the superconducting fill properties. YBCO layer and the substrates, fore details of YBCO and BSCCO boundary product will br presented. 73 Session LN Magnet Technology 9:45 a.m.-noon, Thursday, August 25, 1988 LN-1 LN-4 APPLICATION Of CURKSNT SIMULATION HVTHOfi TO CALCULATE STRUCTURAL REQUIREMENTS OF MAGNETS INCLUDING FORCE 3-D MAGNETIC FltLD Of 3C ALTUUIATOB, qinjfu Li *nd P«i Mug, COMPENSATED GEOMETRIES,* W. Hisscjizatil, Lawrence Buteley Ubontofy - The XI 'M Jiaotonff Unlvaraity — A currant sianUfction ••tbod is cost of stiuctunl compooeMs in i largt supuconducting tnagy storage coil may well exceed the con of a coil and cryoMaL As » mult, the idea of building • combined coil. ih*t is two pr#i«nt«d to ali«ina.t# tha poaiibl* inoraasa in arrora raault- different types of cotts atwnbted in sach a way thai the forces balance and reduce the iota) •d by tba iaa^a ••ttaod to calculata th« 3-D tafnatic fiald of structural requirementi s oft propoted. A suitable jeometry fcu never been found, though tfaa SC alternator la a complicated and boundary condition. Tha several sludies have been aflempted. The reatoa they have not been successful u fundvncnul; boundaries ara raplaoad. bj • large nuabar of currant loopa ap- there can be no force campouaied lokHion ih*l reduce* structural requirements, in this papa, propriately poaitioned at a diatanaa behind the boundary aur- the general problem is presented and an analysis of the energy nored and stresses produced in face ao tbat toe boundary condition on the aatua.1 aurfaca of the structure are described in a fundamental way. Finally, the relation between structural mass tha boundariea ara satisfied. Tha infinitely permeable boun- dary and the infinitely oonductin* ona aay be rtplacad by a M and stated energy E, M <• *—, thM is vtltd {or ait systems h developed, where p is the 'ptira of currant loops and n loops), raapaotiv«ly. In tha for- mer, tha oantral azaa par pair of loop are to be corresponding- density of the structure and ow ii the working stress in the structure ly oonaiatent with the axial and the circumferential line* of the Machine with • Batoning polnta deeignatad on tha boundary 'This work was supported by the Director. Office of Energy Research, Office of High Energy aurfaoe to be owpulaorily iaatiafied with conditiona H • H( •nd Nuclear Physics. High Energy Physics Division. U.S. Dept. of Energy, under Coninci - 0. In the latter, the oantral axia of eaoh loop ahould be No. DE-AC03-76SP0OO9B. and The Electric Power Research Institute. consistent with the line perpendicular to tha boundary surface with D matching points designated on the boundary surface to be ocwpulsorily satisfied with oondition Hn*0. In ««ner*l ca- ses, we suppose a total of {Zm*n) currant loops and (av*n) •atoning point* for the boundary conditions. And (•+!*) aiarul- LN-5 taneoua equation* aey ba sat up and (2ai«-n)uakBOwm currents asy be aolved accordingly. The nagnetio field can be calcu- STRUCTURE OPTIMIZATION OF SPACE BORNE TOROIDAL MAGNETS. X. Hutng, Y. H. Eyssa, H. K, Abdclaalan, L. lated by numerical integration. Tor the sake of checking the El-Harazkl, and H. H. Abdelnohaen, Applied Superconductivity aocuracy of th* solution, besides the Matching pointe, a de- Center. University of Wisconsin - Toroidal geometry Is finite number of points stay be sat on the boundary surfaces. attractive for space energy storage nagneta because It has The calculated results thus obtained for the model of tha SC very snail external Mgnctlc fields. Several configurations alternator are proved to be closely consistent with the mea- Including constant tenalort D-shape, constant tension CD-shape sured value* and thin D-shipe torolda art considered In thla study. Quality factors for these configurations are developed and compared. Hlnlauai weight la one of the najor enphasls In deBlifnlnif stucc borne sasnetap An optlMlzaclon study al^ied LN-2 towards nlnlaua weight under certain constraints on nodule size and weight hat been carried aut< Thia study Includes a APPLICATION Of IMAOti HaTHOD TO CALCULATE 3-D KaOHJHC PIILD AH) PAKANftTUS OF SC ALTHUiATOS, Qingfu Li and »ei Wang, specific strength and specific nodulus, and * study on the Xi'an Jiaotong University - - An imag* method, which has the Efl/H, scored energy per unit aass. Soae typical structure prominent advantages for its clearly phyaical concept* simpler problens such as buckling In the bucking cylinder are programming procedure, ready adaption to tha change of design discussed. parameter• and dimeaaiona of the atonlne, ie ueed to help cal- culate the 3-D magnetio field and the parametera of the SC al- ternator by taking into consideration of the finite length,the actual abape of the winding and the complexity of the bounda- ries of tha machine. The finite length and the atepped boun- LN-6 daries tend to make tha magnatio field in the and regions be weakened gradually. The calculation, in this case, will be NbjSn COATING OF HIGH PURITY U CAVITIES, U. Daubach, oarried out by aeeuming the image of its end region to be de- C. Hiiller, M. Peiniger, H. Piel, and R.U. R8th, Bergische Uni- viated outwardly aad adjusting the inclination of the image ersitAt-Gesanthachscriule Wuppertal, Fa> hbereich Physi current aa well as tha poaitiona of ita atax ting point Superconducting Nb cavities fabricated rom high purity stievt aad the terminating point ao that the boundary conditions win material or postpurified by solid gette with Y or Ti provide be well satisfied. Por the influence due to all of the boun- high field and Qo levels due to the the stabilization of daries other than tbat of end regions as described above, we defects. Por accelerator applications ei ipecially at fi are used to adopt the image current as usual. With tha appli- above I GHz the coating of such cavities with Nb3Sn 1. cation of th* Blot and Savart Formula repeatedly,numerical oal- rewarding because of the significantly reduced rf loss culetion method ia uaed to caloulate the 3-D magnetic operating temperatures of about 4.2 K. We have devclopi fialA due to tm* oolls by integral directly and the magnetic fied vapor diffusion technique using specially constructed UHV linkage by line integral of tha vector magnetic potential to furnaces to produce uniform Nt>3Sn layers on I and 3 GHr accele- obtain the inductance of a coll* The reeulta of the numerical rator cavitiea without loosing the high theroijil conductivity of calculation of a SC alternator model.which has two interchan- the Tib wall. In a first experiment with a single cell 3 CHz geable armature windings — itralght and helical — have been cavity of medium purity niobium (RRR • 160) we have achieved observed a good agreement with the measured values. £ACC" IO HV/>m with a °*6 ^i" thick NbiSn layer. This iu so far the highest Eact: value for our NbjSn cavities but it is low compared to the 25 MV/ro achieved in the same cavity bpforc same in both cases within the resolution of our tetnperaturt LN-3 mapping system* Possible reasons for the reduceu breakoovn field for NbjSn will be discussed on tin' basis of thermal made! CRYOGENIC HICROSTRAIN MEASUREMENT USING LASEK LIGHT calculations. INTERFERENCE, T. Chart*, v.. IVRSB^ K. ftgntsuna, K. Kaiiio and 7. Oniahi, Electrotechnlcal Lab. HITI Japan fc°Francis Bitter Na- tional Magnet Lab, MIT - We have developed a new system of cry- LN-7 counting He-He LASER light interference pulses generated be- tween two half mirrors ir. testing extepcion of a anr.ple si.erl- SUPERCONOuaiNG PROPERTIES OF B1 NITRIDES FILMS nen. The system directly measures an absolute value of B cryo- OBTAINED BY GAS-ftTAL REACTION FOR R.F. APPLICATIONS, genic microstrain In a unit of a 1/2 wave length of the LASER light ( 310 ran - red LASEP or 266 nn - green LAKER in liquid V.e.) P.Fabbricitorc, PFcmmdcs, G.CGAMICO, HMmtnlch, RPirodl, INFN For this reason, the method has the advantage of the conven- Sczlone dl GENOVA - Superconducting critical field and critical tional strain gauge method in absolute measurement or Tree cal- temperature of nitrides rums (NM4) as a function of the heat ibration. An output signal of the aicrostraii, fror. cryostat of the creep te3t facility is a LASER light signal, not any el^c- treatment under controlled nitrogen pressure are determined The characterization Is performed by two steps: noisy cisrcu*c31ances e• s• suferconducting niafinet systeiQ^ thi^ 1) NoN samples are reacted In a foumace filled with nitrogen LASEP nethod of detecting or monitoring a cryogenic nicroStrriin is considered to be superior to the r.train gauge method. The and then tested to check the critical temperature biggest design probieo of the optical method was th<' so-callod 2) A r ( cavity Is built by bulk niobium and reacted as the long term stability e.g. a thprnsl contractloti «n>J expansi on tested samples, RF tests are performed at 45 GHz to measure the sented. Typical cryogenic creep test result, o OH [.olyt*>lm- surface resistance and the critical field fliicroethylene (FTFE) knovr. as Tefron are Fiict. presorted. Several samples have been produced at a reaction temperature of about 1500 "C at different nitrogen residual pressures and reaction times The temperature cycle or the reaction has been round to be a critical parameter, due to the formation of anwanted non-superconducting phases as NbN 1 at SOX N or low-critical temperature phase as NbjN 74 analytical relation Jc=f(B) can be obtained from the LN-8 exper1 menlal data by using the least square method. Therefore it can be analytically used for the INFLUENCE OF FIELD EMITTER SWITCHING PHENOMENA ON THE PERFORMANCE OF SUPEERCONDUCTING RF CAVITIES, the max I man field Baax in the magnet binding, the Q. S. Shu. W. Hanung, J. Kirchgcssncr. D. Moffai, H. Padamsee, D. Rubin, J. field distribution of the double pair Heiaholtz coils Scars. Laboratory of Nuclear Studies. Cornell University. Ithaca. NY 14853. - The phenomena of switch-on of pre-breakdown emission current has been me thod. The opti»izatI on problem for the magnet i c observed in DC field emission studies. We report on switch-on of emission field homogenelty and the 1 east coiI volume can current in supcrconducting(SC) RF cavities operating at high surface electric natheaatleal Iy Iead to a non11 near equalion and t t is fields. The switched emission state, which we call state II, is the most serious rather difficult to be solved. An approprlate probrem we face in pursuing even higher electric fields in SC cavities. It is numerical method hts been developed to solve it. A observed thai due to 1 -2 state It switched emitters, ihc loial deposited power compu ter program has also been cons trueted with whi ch by impacting electrons will increase by a factor of 2-3. and the cavity field we have made a scries of designs of NNR~imaging level will decrease simultaneously.' The switched emission continues superconduct unabated even at the reduced field. A high speed supcrfluid He temperature parameters. mapping system was used to locate and characterize the activation and evolution of state 11 emitters. Suppresion of the excess emission with RF processing is possible upto a point, after which He processing is necessary, but not completely successful. Upto now the best results after overcoming state II rmitrers is 45 MV/m (1125 Oc) surface fields in our 1.5 GHz 1-cell LN-12 Nb cavities, achieved by UHV heat treatment followed by He processing. OPTIMAL DESIGN Of KR1 MAGNETS WITH MAGNETIC SHIELDING, "Work supported by the National .Science Fundation. with supplementary A.Iiihiyaca, M.HonSefc, N.Ishidi anj T.Or.uki, Departnenl cf suppon from the US-Japan collaboration. £lectrlcai Er.gttieering, Was^ds UniverBity. - In *-ht c-nue of or. MR I installation in ncapiials, the lagnetic shielding is often roaulrpd to protect tht? ^riVircr.D^nt Tree th^ Dtronfj ieQkfig& sn^netie f]ux and tc reiiuce the lnTluence of environaentel cagnetic subBtanees or the hcnagenelty. In the previous paper, LN-9 we proposed a new optioal iesigr. aetfcod Car MR1 oagnetfl with oagnetic shielding. Thie aethod la a coupling procedure cf the A LABORA1ORY SLFfcRCONDLCTING HIGH OHADIK\T NAG\ET!C SEPAHATOB L.O-Yan. Y.J-Yu. Z.K.fcang. •he oathecailcal prcgranilng method for ac-ving the Z.Y.Kao, Z.X.Ye. C.L.Xue. P.Ye, Y.L.Cheng, X.M.Li, corresponding optiaizatiori yrobleo. 'JP car, easily consider the 4.k.Kong, H.T-Iang, Institute of £|ectrical conditions which restrict the leakage aagnetlc flux Tram an MRI enginee ring, Academia Sinica. BeiJing, China - In cngr-et, thp cagnetic flux density ir. the ceil winding, and the order to know the effectiveness of hi£h grad tent caxisuE coil rurrent density by etploylng the aatheaatical •a^netic separation for Kau tin clay purification and progracsing sethed. In this paper, the relative oerits of coal desuIfui> z* 11on in China and to develop suitable three different types of sagr.etlc shielding hav*- been technology, a superconducting HUNS facility has been inVPStigated and cocpared '-sing the presented optical design constructed and put into operation at the institute oeT^iod* The first Is ti conv^nlilcnfil accrosch vhich sets a of ElectrIcal Engineer trtfi of the Chinese Academy of t*iici£ and heavy iron yoite &t*cund the oain oagnet* Tne second Science. The working separation chamber is HOfin in iii a ocni'ination of an ircn ycke and a rocn shielding which JG dia«eter and jounm in length. The magnet is wound tc pla~e a thin Iron shield en the nallo. The laet is to use with 0.75 and o. 5am i n d nine tei NbT i supei conduct i ng an active shielding which adopts superconducting coils tc coaposite. The winding is compact and wax-fi11ed. The cane ' the aain field, In otead of the iron yoke aa a prisary tes t proves th»t the magnet can operate at 5T. Some shlelair.g of tr.e aecund cne. Results of a 1 .C-tesla-B8gnet special attentions have been pa id in design and construction uf the magne t cryostat in order to work as long &H PORK i bl c. In the ^et beneflcicition mode, there are t*u sepaiation systerns avai1ab1e, one is the upward pumping feeding system and another In *ilh the downward gravity feeding. The rate of flnw and the linear velocity are 0-0.5 I /» and 0-100cm/s LN-13 respectively. The preliminary sanpl e test results for Kaolin clay pui i f I icaliun and coal desu I f ui' i Kat i un MAGNETIC SHIELDING BY A TUBULAR SUPERCONDUCTING WINDING IS PARALLEL AND TRANSVERSE FIELDS,* K.TaUhata, S.Nlahijla». M.Ohgaml, T.Ok«d«, S.Nakagawat, H.Yoshiv*+, ISIR Osaka Lntveraity, Ib«c*k.l, Osaka 567, +Kawas«kI Heavy Industries Ltd., Kmwasaki-cho, Akashi-clty, Hyogo 673 Hagnetic shields with superconducting windings have been studied aiming at a practical application of superconducting shleldlngs. The LN-10 tubular shields were aade by windings using NbTl S!TEHOMU'criSC PMMANFST SUBNETS* Stffan L WipT' and multlfllasentary composite wires and impregnated with Wood's Jlenr-. I l.aqucr ("nnPu»«. Inc Lm Abnv-s NM. 75 Session MT High Tc Superconductors: Magnetic Properties and Applications 1:30-3:15 p.m., Thursday, August 25, 1988 MT-1 MT-4 ENHANCED Hd AND LOW-FIELD FLUX TRAPPING IN HIGH-TC THE FABRICATION AND CHARACTERIZATION OP HIGH TEMPERATURE CERAMIC SUKRCONOUCTIHG SPONGES, £. W. Collings, A. J. SUPERCONDUCTING MAGNETIC SHIELDS, J.U. Purpura and T.H. Clem, Harkworth. and K. R. Harken, Jr..BATTELLE, Columbus. OH 43201, Naval Coastal Systems Center - Tubes fabricated from arnd R. W. Rollins, Ohio University, Athens, OH 45701 - Magnetic poJycrystalJine JfBa^Cu307.5 arc characterized. Details of the hysteresis studies have been carried out on both powder and fabrication procedure are discussed. The sicroatructurc and sintered samples of "1-2-3" high-Tc ceramic superconductor (of composition or the tubes determined from n-ray diffractomctry, nominal composition, YiB«2C"3Oy)- Estimates of Hci, the lower SEN and x-ray dispersive analysis are described. The tubes have critical field, have been obtained from the results of field also been characterized by means of SQUID magnetomctry. In cycling to +/-17 kgauss at various temperatures between 4.2 and particular, the axial and transverse shielding effectiveness or 92 K. In a second series of experiments the field-cycling the tubes have been measured and these results arc compared with amplitude was incremented in steps of 50 gauss starting at 100 theoretical predictions. The temperature dependence of magnetic gauss, whereupon it was noted that entry into the nixed state fields trapped axially in the tubes has been measured and was delayed to fields many times larger than Hci(4.2 K). It is estimates of penetration depth are given. Studies an flux believed that the reason for this has to do with the magneti- creeping into the tubes are described. These experimental cally porous nature of 1-2-3 (and possibly other high-Ic results are correlated with resistive measurements of Tc and ATc ceramics) which permits field penetration into the surfaces of performed on pellets processed in conjunction with the tubes. regions that are dfmensionally commensurate with a penetration Findings from the microstructure studies are correlated with the depth, the existence of which was noted in earlier low-field observed superconductivity properties. Finally these results on magnetization temperature dependence studiesU. "id elsewhere). the high temperature materials arc compared to results obtained If field penetration "consumes" an appreciable fraction previously on tubes made from conventional superconductors. of the material's volume, the energetic requirement to terminate the ftux-exclusion state by transition to the normal state (type 1) or the mixed state (type 2) is delayed to fields higher than the usual Hc or Hcl, respectively. Artificial superconductors relying on this principal (initially expounded by LondonU)) MT-5 have been investigated in the early 1960s both experimentally (Pb in porous gUssO)) and theoretically (a fine-scale laminar MEISSNER MOTOR USING HIGH-Tc CERAMIC SUPEROONDUCIORS, structured). A.IAKEOKA. ft ISHIKAWA. K.HIRI. U.SUZUKI. K.KUWANO. Functic-nti (1) E. H. Codings et a I.. Adv. Cryo. Eng. (Materials) 34^ Materials Research Center, SANYO Electric Co.,Ltd. - We 633 (1988). (2) H. London, Proc. Roy. Soc. (London) A152. 650 (1935). manufactured • new superconducting motor using bigh'Tc oeruiic (3) C. P. Bean, Rev. Mod. Phys. 36,. 31 (ifffl). superconductors for the first time in tbc world. We c*ll it * (4) A. El Bindari and M. M. LitvaTT Rev. Hod. Phys. 36^ 98 (1964). "Heissnor Motor" , which utilizes tbe repulsion caused by tbe Hcissner effect and tbc difference of temperature around its wheel to drive the motor txle. We investigated the fundamental characteristics of this motor. It consists of a 54 ma4 wbacl MT-2 with 16 superconducting plates around tbc wheel, a heater KAGHET1C SHIELDING EFFECT ON OHIDE SUPERCONDUCTING above tbe wheel, and a permanent magnet below. The plates are PLAT-S. A YaJiara and K ffatcuba The FUTUKAHA E iec 111. fs. Ltd prepared by sintering • compound of YBa,Cu,0,.i, and are 15 mm - •> hav# studied mnetic shielding by ende supercani'jciin? in diameter and 1.5 MI thick. Tbc critical temperature is 93 plates for applicatier to Frcsuce a shieldirj apparatus A K Cooling down only tbc lower part of tbc wheel in liquid •dfneiic fi*ltJ parallel :o the Plate.coaled to "K.«as applied nitrogen, a plate near the magnet repels according to tbe Meissner effect and generates a torque to drive the motor. The 50 fl x 50 •• plates were used Kith d thicknes3.fi. aftjeh Mas rotating superconducting plates arc heated in turn at tbe top varied froi 0 5 tc b le and :he &,pt'.i?A field tr.ier.s ::y -JE*-* of tbe wheel and turn into tbc normal state. At this state, uas 0 to ]0C oersteds tbc plates «asily approach to tbe permanent Mgnet. At present, tbe motor rotates at 40 r.pm. and has a torque of exceeded a critical ;n!ensity.Ec..:he ia«neti-: flu* penetrated 0.6 ftf-cm. praportional to the Thickness.d of the piate spec liens The results Here analyzed fcy !he critical state' mc>i*? I Th* speciiens were assuied ID be bulk superconductors, whose aime MT-6 superconduct inj sufc-strrJ:*ures «»re et I naively ir IT rcin^ctPd SYNCHRONOUS ROTATION OP A PLOATING HAGNET IN 3.ctd in MtiLch irtt&r(r&nul&r curren^'pinnirj p& T hs n &rfc press^t AH ALTERNATING MAGNETIC F1BLD, J.C. Haciarlane and R. Driver, CSIRO Division of Applied Physics, Sydney, When the appiied field was raised abave 3a> xht Bedsur^i Australia 2070 - We have observed stable, synchronous flux shoved hysterisis. mtti a tagnetic flux trapped in the rotation of a bar magnet levitated above a ring o£ y- fca-Cu-0 at 77K; the roLation is maintained by a single-phase alternating current in a solenoid located outside the magnet-superconductor system. The froi lagn&tic fields of intensity upto Bo* could be r!ei/plopee alternating field amplitude IB of order O.I mT (1 Oe) by the \i5e cl these neM superconducting oxide sys:»a rms, and its frequency is around 20Hz. Possible mechanisms for this new phenomenon arc discussed with reference to other relevant experiments on flux penetration (1) and motion (2) in ceramic supercon- ductors. The effect is not found with a circular MT-3 magnet. It is proposed that field maxima related to HACHETIC SHIELDIHC BY SUPESOOrOKTrNG Y-Ba-Cu-O HOLLOW the shape of the magnet penetrate the superconductor CTL1HBEHS.« J. 0. IlllU. H. P. Ifaley. and H. Sheinberg. Los by disrupting weak Josephson-like contacts. The Alams National Laboratory - ¥e have performed K]» flux tube- applied ac field, if close to the natural relaxation typ* experiment* on hollow •upercoriducting cylinders of time for flux motion in the superconductor, provides sintered ceraalc YBaaCuaOT. A lube of 7.3 mm ID. 97 me long, "positive feed-back" to maintain the magnet's and with a vail thickness of 5.6 mm excludes on applied field rotation. The effect has been recorded on videotape. of about 40 Oe at 75 K and traps a large remnent field. The References: (1) J.C. Macfarlane, R.B. Roberts and R. shielded field corresponds to an average critical current Driver, Appl. Phys. Lett. 51, 1038, 28 Sept. 1987. density of about 90 K cwT3. Flux tube experiments ai various (2) R. Williams and J.R. Matey, Appl, Phya. Lett. wall thicknesses and temperatures will be discussed in terms 52 f 751, 29 Feb. 1988. of critical state models for bulk and granular superconductors. •* fork supported In part by the U.S. Department of Energy 76 help of microscopic and ciystalographic observations/ of MT-7 materials, using a scanning electron microscope, and an X-ray FABRICATICK OF Y-Ba-Cu-O SUPERCONDUCTOR P3B MACMETIC diffractometer. Our results showed that Y-Ba-Cu-O BEARING, M. Ituh, H. Ishigaki, and A. Hida, Kmki University superconductor had a possibility to be used as magnetic - We have studied the preparation of a pellet of Y-Ba-Cu-O bearings. superconductor for a purpose of application to magnetic bearings. Pellet sables were formed by pressing the calcined powder which contained "t-fh1 5s^0^ and CuO, and trten sintered at the temperature of 91CT. Mechanical properties as well MT-8 as the electrical properties were measured. The mechanical properties included load carrying capacity of magnetic SCREENING AND LEVtTATlON BY HIGH T- bearings (repulsive force due to the Meissner effect! as SUPERCONDUCTORS. A.M. Campbell. Department of Engineering, we! 1 as material properties such as hardness, fracture University of Cambridge - The fields due to a magnet and a superconducting strength, and density. The electrical properties included sphere or sheet are calculated assuming the superconductor does not carry a bulk resistivity, magnetic susceptibillty, and critical current. The screening depends on nz/c where c is the screen thickness and z temperature. Several parameters ard processes of fabrication the size of ihe system. Only if this factor is small arc significant screening and have beer examined to improve the above properties. These lcvitation observed. The friction between a levitated magnet and a include the pressures of powder pressing and annealing superconducting plane, and the forces tending to rotate particles, are also conditions. Effects of the above fabrication process on calculated- The turning forces arc likely to be dominated by pinning and the reH±.anical and electrical properties were discussed with the shape of the panicle rather than the anisntropy. Session ML) High Tc Superconductors: Thin Films IV 1:30-3:15 p.m., Thursday, August 25, 1988 MU-1 MU-4 OZONE-PROCESSIKC OF HBE-CROL7J VEa Cu 0- FILMS.* D. MULTIPLE HETHWEPITAXY AND SUPHRLATTICE TORMATION OF D. Berkley, D. II Kin, K. Beauchaap, B. Nease. ft*R . Johnson, lnHHCuUA'BaCuO SYSTB1. M.Tonouchi, Y.Yoahizako, M.Iyori, an) and A. M. Goldman, Culvers icy of Miimcsota ~ Vc present T.Kobsyoshi, Faculty of Engineering Science, Osaka University results of experiments designed to determine the efficacy of — The present work dmonstrateB the advanced epitaxial irowth using an ozone vapor source In the preparation of thin fll«s tpohnology for the high Tc superconductor naleriala. CX.r of the YBa.Cu-0 ("123") Buperconducttng oxide. The vork is cmphaMiH was placed on conducting the Multiple heteroepitaxi&l directed at producing Mgh-quality Ellas of this MterUl growth and the superlattiet.- formation, both of which are without a post-anneal £r«atn>nt jii.d without using high pr«5- believt*! as hey technologies for the bnsic research and future di'vic-c ajiplicationH. As the first step to the superlattice fonmtion, we haw investigated an ultrathin f3 1M epitaxy of faces imcontaslnated by exposure to an environment l#i* high Tc superconductor. Whthin the thikneas ICSB than 10na, the rryatal Unity of the nagnetron-Hpottered YBftCuO fibi were greatly enhanced reactivity with respect to Molecular oxygen nffM:i«l, tt» large extent, by t.ho HUbatmte Material. The of an ozone jt-t directed at thin films of the metallic con- deformations of the p?rovakit,c structure were commonly stituents of the "123" compound This hat been accomplished nlwprvpd whenever SrTiO- was uaed and deipite of the using quartz crystal aonitors (QCM> to Masure the change in or ient At ion. Whereas, MffO substrate gave the excellent thickness due to oxide growth of films pre-evaporated onto the results. As the second ntep, the attempt was done to grow real QCM The eftvet of applying ozone during and after the multi-heterostructure and the superlattice using LnfiaCuO (Ln= Nd, Kr) / YBaCuO / SrTiOg systeme. The Bound RHEED pattern was and Knudsen cell sour IT os will be reported. ohserved for the former consisting of five alternating layers ( rach lnyer being 60m thick ). However, in the latter, the 'Supported in part by the Air Force Office of Scientific crystal line dpformation taken place at the bottom thin layer Research under Cram 87-0372 and by the Central growth |1.2n«l propagated up to the top (the six layer). The Administration of the University of Minnesota forumUon of tjje Buperlnltice on the MgO substrates is now undnrwny, MU-2 LOU-TEHPEJtATUHE IN-SITU GROWTH OF Y-1A-CU-0 THIN FILHS MU-5 ON SI, A12O3 AMD SrTlOj SUBSTRATES.* R.H. Silver, A B. Berezln. OX 1 OF- SU'KHCOMILCTOH BSCCO AM) VBCO FILMS ON SrTiO, AND «nd A L. d« Lotann* - tfe hava built • differentially pumped VSZ SlItSTRATFS I'RKPARH) BY LASER SISTHRD I'OHDER DKPOSITK PROCESS, electron btiB «vaporator deiljntd to deal vlth the special K.Aj-.itsuia.T.Ohdra.K.L'chijaia.K.Tsukaioto, and T.V.inaei&a*;i requlttaents of thin fllii of oxide superconductors The growing surface li ipraycd Kith plaiaa-aEClted oxygen while the Hlrctrotrchnic.il Laboratory . S critical te»peraturn of oxide sources and rate Monitors operate In a lov background pressure superconductor risi»s fro* 23 K of \b,O lo 90 K of V-Ba-Cu-O(V(lC This illoHt us to grow 0.7 alcron-thlctc fllas of Y-Ba-Cu-O on II) and 100 K of Bi-Sr-C.i-Ctii-OtnSCCOJ.Tficsf- iaicrials h.ivn highur SI, AKOj *nd SrTlO-j *ubitrat«« at a aubatrtte tenparature of possibilities of realizing a futtirr supcrrondurtJPR drvic« vhir.h 54QC which ire superconducting without the need for annealing. The resistive traniltloni of aoit fLias shov an orutt of 9QK works lit liquid nitroKcn tPipor.iturn.Thin fill grovtli torImi<|ui's •nd zero raiistance by 6IK, with alBllir properties Independent of new high Tc oxide supfrrondurtors an; real }y iR^orlant •f the substrata used. The beat fllas shov R-0 at 83K on <>5por;iit 11 y for the olcctronir duviro iipl'l irations. Me h/ivc bvf-u SrTi0j(H0J. The films show a uniform grain structure at the dnvetopirm d LASf-R SINTEKKO POKDfifl DEPOSITE process.* high poKcr resolution LinIt of a high-power Noaarakl optical microscope CO, I.ASF-H be.ia is applied Lo jin oxtrcaly sull quantity of nSCCO (appro*. 0. !> silcron). SEH Images. on the other hand, show alnost no structure due to lick of constrast X-ray or YBCO fine ponder vhich is dropped froa .t iir.ro feeder and diffraction indicates * preferred orientation for growth on deposited nnlo ,i substr-itc.br have successfully andc Ba-Sr-Ca-Cu most St and SrTlOj substrates. The Uportince of the various -O(BSCCO) fills on ¥ BJ siabiliznd Zr(VSZ) .ind SrTiO, substnHns process paranatirs Is currently being evaluated. The by this L.-isrr Sirttnred I'ovdrr n«'|i')sit« prorensu. This fill hus temperature of completion of the suptrconductIng transit Ion 1 seams to depend strongly on the oxygen pressure. A preliminary about 80 K ons^l tcipcr<*tLurr, Nor* details ami rcsuls of rr.nr^y •easureaent yields critical currents of at least 104 A/cto at 4.2K for a fila on silicon. * Supported by Motorola, Inc., HSF-DHR, and AFOSR MU-6 CnafARISON OP YBI9CU,0- FILMS GROWN BY SDLID-STATE AND VAPDP-rflASE EPITAXY,* J. TUvacchio, J. R- G»v»ler, J. Greggi, MU-3 and A. I. Brag'uski, Vestinghousc RAD Center - Epitaxial films of YBagCu-O- have been grown on single-crystal SrTiO, and MgO OPTIMIZATION OF THIN-FILM YBa2Cu3O7 DEPOSITION substrates by two routes using rf and dc magnetron co- BY DC SPUTTERING ONTO SAPPHIRE SUBSTRATES, EJ.Tomlinson, sputtering. In the first case, aaorphous oxide films were G.W.Morris, R.E.Somekh. Z.H. Barber, K.Butler, M.G.BIamire, deposited at z substrate temperature 400*C and the crystalline P.L.Sampson, and J-E-Evens, Depi. Materials Science & Metallurgy, film grew by solid-state epitaxy in an in-situ post-anneal at University of Cambridge, U.K. • Thin films (0.5 urn) of the high temperature ""850*C. In the second case, a substrate tenperaturc of ~650*C superconductor YBa2Cu3O7 have been deposited onto sapphire substrates was used which was sufficient to crystallize the film as it was coated with an oxide buffer layer by d.c. magnetron sputtering. Both metal deposited. By a comparison of in-situ RHEED and XFS with Auger (1.4 A/sJ, and hydrostatically pressed and sintered ceramic (0.5 A/s) targets depth profiles and transmission electron nicroscopy, we have have been investigated. The effects of the deposition conditions on the found that a auch thinner degraded layer forzed at the composition and superconducting behaviour of the films have been studied to substrate/filn interface in the case of vapor-phase epitaxy, optimize ihe quality of the films. The need to avoid a high temperature < 10 na. Only the in-sjtu XFS leasurenents of the filns grown (>850*C) heal treatment with sapphire substrates, so as to minimize diffusion at -650*C showed the Cu spectra typical of vacuum-scraped into the film, has led to the use of a healed substrate holder during deposition, YBagCu,07 surfaces. Comparisons will also be made of film with deposition temperatures in the range 650-750°C. The deposilion nicfostructure, growth orientation, and stoichioaetry of the temperature has a marked effect on the relative sticking coefficients of the surface layer. The effects of the alternative growth atomic species, and so, in the case of the ceramic target, the development of a techniques on film properties relevant to microwave non-sioichiomeiric composition was required for depositing films ai elevated applications and tunneling will be discussed. temperatures. Activated oxygen has been incorporated into the deposition process to enhance the oxygen uptake of the films. Supported in part by AFOSR Contract No. F4962O-88-C-OO39. 77 Session LO CEBAF Magnets 1:30-3:15 p.m., Thursday, August 25, 1988 LO-1 CEBAF SUPERCONDUCTING SPECTROMSTER Spectrometers to detect electrons and hadrona in coincidence. DESIGN, *P. Brindza, J. Akont, R. Carlini, L. Harwood, J. These spectrometers require two high accuracy dipoles each to LeRow, B. Medcing, J. Mougey, J. O'Meara, CEBAF-The provide momentum analysis. A modular (truly interchangeable) CEBAF Experimental Nuclear Physics Program is baeed upon cryostable design was selected to meet the requirements for this three independent facilities each with unique capabilities. Hall A application. The characterstics of this dipole are an effective consists of a pair of High Resolution Spectrometer (HRSS), Hall field length of 3.14 meters, a peak operating field for 4 GeV/c B features a Large Acceptance Spectrometer (LAS) and Hall C particles of 1.7 Tesla, and a uniformity of 1 x 10"4 AB/B over will have a high acceptance, high energy electron spectrometer the good field region which is 1.00 m wide with a gap of 0.3 m. and matching special purpose hadron spectrometer. We will The large stored energy of 3.5 MJ and mechanical consideration demonstrate that performance and operational requirements of in the coil cryostat lead to a cry out able design using a copper these devices can be met most effectively thru the use of auper- stabilized NbTi Superconductor with a very high overall copper ' conducting devices. The Hall A and Hall C spectrometers to superconductor ratio of 50:1. The dipole is a fully iron require high quality, large volume dipole magnets, that although dominated "H" geometry with both coils in series in a common are not beyond the range of conventional magnets, the most cryostat. The design details will be presented along with economic choice is for a superconducting device. The spectro- conductor analysis, cryo-atability analysis, quench analysis, meters require high gradient, large aperature quadruples that cryottat stress analysis, and cryogenic analysis. Field and force could sot be produced without the use of a superconducting Cos caculations will be presented. 28 device. The LAS requires a "thin" layer volume toroidal magnet for momentum analysis. This device would be unachiev- •Work performed under Department of Energy Contract able using a conventional type coil and the operating cost would #DE-AC05.84ER40150. be prohibitive. The physics requirements and the rational basis for the design selection will be presented. The analysis that supports the cost effectiveness of the selected design will be presented. The cryogenic system will be covered as well aa the integration of the Experimental Hall Cryogenic system and main LO-4 CEBAF Central Helium Refrigerator. AN IRON-DOMINATED SUPERCONDUCTING QUADRUPOLE FOR CEBAF;" L. H. Harwood, S. R. Lassiter, and W. Tuzel - The present design for the high-resolution •Work performed under Department of Energy Contract spectrometers at CEBAF requires a front quadrupole (Q0) that #DE-AC05-84ER40150. has a gradient x length = 6.8 T with a " good field" aperture (1 x 10 uniformity in gradient) of 10 cm radius. A room temperature design was found too power hungry and interfered with the beam. Engineering and construction of a small LO-2 COS(20) magnet was considered to be quite expensive. A A SUPERCONDUCTING TOROIDAL MAGNET FOR Panofsky design was not considered due to the extreme THE CEBAF LARGE ACCEPTANCE SPECTROMETER, 'J. sensitivity of the field quality to errors in conductor placement. O'Meara, J. Alcorn, P. Brindza, M. Chew, G. Doolittle B. A conformal mapping of a window-frame dipole into quadrupole Mecking, C. Riggs, W. Tu«I, CEBAF-The CEBAF Physics geometry worked well at NSCL (1). A similar design has been Program has a Large Acceptance Spectrometer covering nearly all developed with the following characteristics: Physical length of the 4r solid angle for studying complex electronuclear (total) - 1.2 m; iron length = 1.1 m; iron outer dimensions = interactions. This device relies on a six coil toroidal magnetic 54 cm x 60 cm; peak gradient = 0.2 T/m; pole radius = 2Q field to provide momentum analysis. The desire to maximize cm; " good field" radius = 10 cm; coil peak field — 1.5 T; solid angle coverage led to a thin superconducting toroid design. conductor = I mm dia.; Cu/NbTi = 7:1; current = 400 A; The main device has the following parameters: an outside turns = 250/quadrant; stored energy = 50 kJ. diameter of 4.6 m, an active length of 5 in, a peak field in the toroidal volume of 1.2 T, and a stored energy of 18 MJ. An 'Work performed under Department of Energy Contract #DE- intrinsically stable design was selected to minimize the overall AC05-84ER4Q150. space requirements of the toroid. The individual coils of the toroid are approximately kidney shaped, the negative curvature coming from the requirement to have good particle focusing properties. The overall design will be presented along with stress analysis, conductor and quench analysis, heat leak analysif LO-5 and cryogenic cool down analysis. The six coils are powered in A SUPERCONDUCTING COS 2$ QUADRUPOLE series and are passively protected by a set of diodes and heaters DESIGN FOR THE CEBAF HIGH RESOLUTION in each coil. The analysis and operational characteristics of the SPECTROMETER, *W. Tuzel, J. Alcorn, P. Brindza, protection system will be presented. A. Gavalya, J. Mougey, S. Nanda, CEBAF-The pair of High Resolution Spectrometers (HRS ) at CEBAF require large aperture, high gradient quadruples. A superconducting Cos 20 •Work performed under Department of Energy Contract design has been selected to meet these requirements. The #DE-AC05-84ER40150. quadrupole has a coil diameter of lm and a peak gradient of 5 T/m with an effective field length of 1.8m. The stored energy of this quad is 3.5 MJ. The details of the design of the coil, shrink fit support collar and cryostat will be presented. The LO-3 analysis of the superconductor, quench behavior and coil A SUPERCONDUCTING CRYOSTABLE DIPOLE protecticn system will be covered. The cryogenic behavior of the DESIGN FOR THE CEBAF HIGH RESOLUTION coil along with thermal stress will be included. SPECTROMETERS, 'Paul Brindza, J. Alcorn, V. Bardos, M. Fowler, J. Mougey, J. O'Meara, A. Sana, CEBAF-A major *Work performed under Department of Energy Contract facility at CEBAF is the pair of identical High Resolution #DE-AC05-84ER40150. Session MV High Tc Superconductors: Bulk Properties II 2:00-4:30 p.m., Thursday, August 25, 1988 are present in which this multiple-conductance-peak structure MV-1 is clearly evident and experimental results of tunneling into SINGLE-ELECTRON CHARGING EFFECTS AND ELECTRON TUNNEL- ultra-small metal particles (2.0-10 nm in diameter) which dem- ING IN THE HIGH-TEMPERATURE SUPERCONDUCTORS,* J.fl. Barner ard onstrate the existence of these effects. Also discussed are S.T. Ruttgicro, University of Notre Dame and K, Mullen and E. the implications of charging effects with regard to device ap- Ben-Jacob, Univsrsity of Michigan, Ann Arbor He discuss our plicat ions. latest results on charging effects in small-particle systems +S.T. Ruggiero and J.B. Barner, "Multiple-gap tunneling struc- froffi both the experimental and theoretical standpoint as they ture observed for high-T superconductors: Charging effects as relate to tunneling results in the new high-Eenperature super- possible cause" PRB36, 8o70 (1987). conductors. As previously discussed by UB.t current results of tunneling into the high-T superconductors show string ev'dence *Hork at Notre Dane supported by the National Science Founda- for charging effects as manifest by multiple, peri ; conduc- tion from Grant NSF DMR-86 10375 and Work, at the University of tance peaks. Re discuss new theoretical results i mneling Michigan partially supported by NSF Grant DMH 86 08305 and into systems in which both charging and supercondi. • a effects Grant DAAL O3-87-k-0O07 from the Array Research Office. 78 London penetration depth obtained froe the bulk critlcal MV-2 magnetic fields, which suggests the weak counting effects MAGNETIC PROPERTIES AND MICROSTRUCTURE OF SINTERED HICH- •song superconducting grains. Be discuss the relation between T Bi-Ca-Sr-Cu-O ASD Tl-Ca-Ba-Cu-0 OXIDES, H. Kumakura. A ... and jL. tea also measured the profile of the magnetic K. Togano. M. Uehara, H. Maeda. K. Takahaehi*, H. Kakao* and flui trapped Inside bulk YBaCuO samples with small Hall H. Shlmizu**, National Research Institute for Hetale, *Sanyo Elect., **Furukava Elect., JAPAN- We have measured magnetic ssnsors, and discuss the relation between jt and the profile. properties, H£l and H , values for Bi-Ca-Sr-Cu-0 and Tl-Ca-Ba-Ca-0 polycrystaH ine oxides prepared by a povder method. Nominal composition was Bi.Ca.Sr.Cu.O and MV-7 Tl2Ca,Ba2Cu;J0x, respectively. Magnetic susceptibility indicated that the Bi-satnple contained two superconducting phases with STUDY OF TRANSPORT PROPERTIES AND REIAXAlTOK T^'s of 6SK and 103K. The Tl-sample, on the other hand, contained only one superconducting phase whose T was 105K. EFFECTS IN HIGH-T SUPOTCONDUCTORS BASED ON AC SUS- Hcl at-I7K derlved from nafEnetization curves was 4.5x10 T and CEPTIBILITY MEASUREMENTS, P. Gtattry. P. Lobotka, 1.5x10 T, respectively. Hysteresis in magnetization curve at 77K of Bi-sample was touch smaller than that of sintered and S, T»kmom, Electrotechnical Institute of EPRC, Tf-Ba-Cu-O. Hysteresis of Tl-sample, on the other hand, was Slorak Acad. Scl*, Bratislava — The cowpletx eatgnetic nearly the sane magnitude as Y-Ba-Cu-0. This difference in hysteresis may cotce from the difference In microstructural susceptibility at different teajpermturtta, frequen- feature. H ,'s were evaluated from the resistive transition cies and amplitudes of the Magnetic field v»a MMU* curves obtained in various magnetic fields up to 12T. For both samples, low temperature portions of the transition curves were red for hiefa-Tc superconductors prepared by diffe- shifted to lower temperature with increasing magnetic field, rent technologies (sintered ooapactt, «ol-g*l, era- while high temperature portions were only slightly influenced by the magnetic field. However, Tl-sample showed much sharper porated and sputtered thin fllmw). By coejpaxlnc tbe transition curves than Bi-sample, when compared In a same both parts of the susceptibility, an original aw- magnetic field. H .(midpoint) at 77K, estimated froa a linear extrapolation, was 5IT and 50T for Bi-sample and Tl-Bample, thod tma developed to calculate tbe critical current respectively. These values were about twice as large as that of dmntity, Thm obtained value* are in * ^ood agreeaent Y-Ba-Cu-o due to larger temperature margin for 77K. H 2(midpolnt) at OK, estimated using UHH theory, was 108T and with the resietively seasured one*. Fro* the suscep- 130T, respectively. J measurement was also carried out at tibility •jeasureBWitts, the current-voltage characte- various temperatures and magnetic fields. ristics and the Measured relaxation effects, conclu- sions are wade on the transport properties of diffe- MV-3 rent laaples (intra- ve, lntergranular critical cur- PREPARATION OF Y Ba.CiuCv POWDERS BY MOLTEN SALT ROUTE, rent densities, the role of the proxivity effect, *H. Akinc, A. Celikkaya, R.Tlillis. Department of Materials Science and Engineering, Iowa State University - Y Ba.Cu-0- , powders were percolation m»chanis«r etc.). prepared by mixing Ba(0H)2-fiH-O. Cu(CH-C00>2'fl-O and°Y(S0^) powder and heating to about 1OO"C. Helt produced first a paste MV-8 then underwent a pyrophorlc reaction to form a fine oxide powder. The oxide further was heat treated in oxygen acnosphere to produce NOVEL "BATHYSPHERE" CRYOSTAT FOR VARIABLE TEMPERATURE superconducting phase. Influence of procedural variables on the EXPERIMENTS ON HIGH Tc SUPERCONDUCTORS, John Moreland, Y. K. povder characteristics including slnterability and superconductive Lit, R, H. Folson and T. E. Capoblanco, Electromagnetic properties were investigated. Applicability of this process to Technology Division, National Bureau of Standards. Boulder. CO - fabricate fibers and coatings are discussed. We have developed a novel cryostat for variable tenrperature tescing of high Tc superconductors. The cryostat is a bathy- •Supported by NSF by grant *MSM 8718273 sphere consisting of an overturned stainless steel Devar sus- pended in liquid helium. A sanple-heater-theraoaeter assembly is located at the top of the encapsulated (and theraally insulated} vapor space inside of the Devar. The sample can be MV-4 rapidly cycled from 300 K to 4 K at a maximum rate of 5 K/min PLASMA SPRAYED HIGH T SUPERCONDUCTOR COATINGS, R. G. with a thermal hysteresis of less than O.I K. Helium vapor CaBtro, S. A. Richardson, and P°. U. Stanek, Materials Science and flows through a plug in the bottom of the bathysphere so that Technology Division, Las Alamos National Laboratory - The plasna pressure of the surrounding heat exchange vapor is roughly spray process Is well suited to depositing the new high tempera- ambient. This provides aaple heat transfer to and from the ture superconductor (HTS) oxides onto various substrata materials sample to naintain thermal equlllbrluta in the vapor space. and configurations with uniform coating thicVneasca ranging frosi Results for resistance versus temperature of none high Tc copper 20-200 microns. This presentation describes the spray deposition oxides will be presented. techniques and post coating treatments required for producing large area HTS coatings. Hicrostructures and magnetic and t Visiting scientist from Institute of Physics, Chinese Academy electrical properties of HTS coatings produced by conventional of Science, Beijing, China. compared. MV-9 CHARACTERIZATION OF HIGH T SUPERCONDUCTOR BI MV-5 LUMINESCENCE METHODS, T. FujWara and T. Kobayaahi, Osaka rf-MAGJJETRON SPUTTERING OF Bi-Ca-Sr-Cu-0 THIN FILMS," University - We have systematically investigated photo- and A. Ku3amaul,T C. Roesler.tt J. E. Tkaczyk, j.s. Moodera, C.X. therially stiaulated luiinescancea froi high Tc superconductors Hao, G.A. Gibson, R. Meaervey, and P.M. Tedrow, Francis Bitter in order to establish those luiinescence methods as a powerful National Magnet Laboratory,ttt MIT — Thin films of the high characterization technique and to obtain essvntlal knowledge for T material Bl-Ca-Sr-Cu-0 were prepared by the rf-magnetron the development of nev light-emitting superconducting devices. technique from a stoichiometrlc target In pure Ar atmosphere on In Er-Ba-Cu-0 and Nd-Ba-Cu-0 aystamsi a aeries of sharp esiselon sapphire substrates. The samples were annealed In pure 0, at lines have been observed in the near-infrared region, which are 500°C for 1 to 5 minutes. Their structure and composition were tentatively assigned to electronic transitions between spin- studied by X-ray diffraction and RBS. The superconducting orbit levelB of trivalent Er and Md ions. Their spectral shape transition was very broad, with an onset at 85 K. The upper and/or peak positions are quite different froa those of Er20o critical field wa3 measured. We will describe the influence of and Nd203 as & source material, suggesting that the analysis of target composition, substrate, and the addition of 03 during photoluBinescence spectra gives us the Information about a the sputtering. microscopic field surrounding the rare-earth ions. On the other hand, such luminescence has not been observed in Eu-Ba-Cu-0 and Supported by AFOSR grant FU9620-85-O0005. Tb-Ba-Cu-0 systeas, although Eu^Oo and TbgO, exhibit radiant ..Supported by Coopagnie de Salnt-GoOaln, France. photolumineacencea under the stie meaeureaent condition, which I Supported by the Office or Naval Research. might reflect a difference of their band structures. We have Supported by NSF. also aeasured x-ray excited theraally stimulated luilnescence of these oxide superconductors to obtain further informations about them. In Gd-Bs-Cu-0 system, we have obtained characteristic thernally stimulated luaineseance glow curves, dependent on Gd MV-6 coapoBition, sample preparation condition and cumulative x-ray EVALUATION OF GRAIN-COUPLING STRENGTH OF TBaCuO irradiation tiae, respectively. The activation energies of the SUPERCONDUCTORS BY THEIR MAGNETIC-FIELD PROFILE MEASUREMENTS, related traps are 0.1-0.3 eV in this system. These results show K.Yoshida, T.Klsu, N.Fuchlgul and K.EnpuJcu, Department of that thermally stimulated luminescence measurements are useful Electronics, Kyushu University 36, Fukuoka BIZ, Japan - In to characterize defects included in the materials and to make order to evaluate the strength of grain coupling, which clear the aechaniaa of their creation and annihilation. Recently, we have also observed thermally stimulated determines the critical current of polvery*talline oxtda luminescence froe BiSrCaCu^O. At the conference, the details superconductors, m have studied the relation between tha will be demonstrated. critical current and. the spatial distribution of the magnetic field for YBaCuO thin films and bulk superconductors. Ve used the dc SQUID and the Hall magnetic sensor for the measurements of the magnetic-field pmetntion depth and trapped aagnetic-flux profile*, respectively. The Misurement of the magnetic field penetration depth of YBaCuO thin films is based on the measurement of the loop inductanace of a dc SQUID which is placed on the YBaCuO thin film to be measured, which acts as a superconducting ground plane for the SQUIDr Observed magnetic-field penetration depth i.,, of polycrystalline films deposited on HgO substrates amounts to -l^m for samples with the thickness of l-3ji m and the critical current density jr -10* k/ot at 4.2R. This value is auch larger than the 79 Al l A s z \ I V \ 920%:. 5h Y \ slow-cool iI >. \\ \ S0O-C.5H IWJ I qo«tich 0.73 0.77 OiBl 0.65 100 150 200 250 PHOTON ENERGV (eV) TEMPERATURE (K) Fig. 1 Typical Er-related photoluaine- Fig, t> Sample preparation condition scence spectra in Er-j pBag gCuO,. It dependence of glow curves obtained in iH assigned to intracenter transition M B CO from the firBt excited spin-orbit state ^Ii3/2,.to the x15/2 ground state of Br* . 100 200 300 400 $00 TOTAL IRRADIATION TIME (min) Fig. 5 Cumulative x-ray irradiation time dependence of the intensities of glow peak a - and B observed in GdQ /B&n ftGuO.Thei r dependences are quite different. Fig. 2 Typical Nd-related photolumine- Ba ( uO scence spectra in »d1.2 p.8 ' i' Three luainettcances can'oe observed, which are attributed to transitions between spin-orbit levels, F$/2~ and 11/2^ 3/2" 11/2 3/2 *13/2 BiSrCaCu2O 100 150 200 250 TEMPERATURE (K) Fig. 6 Theraaliy stimulated luBinescenc glow curve obtained in BiSrCaCugO. The inset shows the temperature dependence of the saaple resistivity. W0 150 200 250 TEMPERATURE (K) Fig. 3 Thermally stiaulated lumine- scence glow curves obtained in Gd-Ba- MV-10 Cu-0 system. Their ahape depends on Gd THERMAL RESPONSE FOR COPPER OXIDE SUPER- composition. CONDUCTING THIN FILMS, M- 6. Rizkafla. Purdue University at Indianapolis - The classic treatment of the heat transfer from a current-carrying copper oxide superconducting thin film to a substrate at 30°K was found for the case of a super- conducting thin film used as an electric switch. The calcu- X Ha E HVI I lations were then extended to the maximum operating frequency for the given conduction current. The results of these cal- A 0.11 !.«.»= 1.21 culations Is the thermal response time for the switch due to a 0.1 : pulsed heat source. a 019 5,13 «10 1.21 0.33 c (OOt) 11.17.10) (1911 0 0.2< 1.2S .»' 1.01 MV-11 S RESPONSE OF YBaCuO THIN FILMS TO ELECTROMAG- as E 10.191 II.<2.IO I 11.91) NETIC RADIATION ANP THEIR ELECTRICAL CHARACTERISTICS, : F 0.X 3.oax» 1.21 A.S.Afanasyev,A.F.Volkov,V.N.Gubankov,Yu.Ya.Divin, and P.n.Shadrin, Institute of Radioengincering and Electronics,USSR Academy of Sciences-We have invest i- gated the characteristic features of the interaction Table I Characteristics of glow peaks. of electromagnetic radiation with thin films of E, a and 1 denote activation energy, YBapCugOy high-T superconductor. The current-vol- frequency factor and kinetic order, tage characteristics I(V) of these films and the vol- respectively. tage responses V to electromagnetic radiation with the frequencies f=60-75 GHz have been measured at the temperature range 4-1D0.K. We have found that the be- haviour of V(T) and V(I) dependencies is not con- sistent with those for the bolometric effect,for the electron heating by electromagnetic radiation in the resistive state of superconductor,and for the classi- cal detection on the nonlinear current-voltage chara- cteristic. The model calculations of the temperature dependencies of the resistance and of the response 80 crystal substrates - safine, MgO. Sri it),. Maximum critical temperature at zero resistivity was 1 * 82 K. I he suifane oi films is Eimooth witti pancake-stiajjed gFSins. Ihu tunnel stiut;- MV-12 COWLEX AC CONDUCTANCE OF YBaCuO FILH5, P. K. Srivaatava1, P. Debfily1, H. E. Hintermann1, 8. Jeanneret/, C. Leemann2, J. Weber2, 0. Caccivio2 and P. Martinoli2, [i] CSEM, CH-2000 NeuchBtel, [2] Inatitut de Physique CH-2000 Neuchfltel - Magnetron sputtering from a ceramic YBa2Cu307 target in a mined Ar - 02 atmosphere was used to prepare YBaCuQ films oo sapphire substrates. The superconducting transition of the films was in- vestigated by measuring their complex ac-response to a small oscillating driving field with B two coil mutual inductance technique. The results are consistent with a description of the ceramics in terms of Josephson coupled superconducting islands distributed on two dimensional lattices. In particular, in samples where the Josephson penetration depth is much larger than the sample thickness, the superfluid component, as mea- sured by the imaginary part of the response, exhibits a sudden drop in the region of the transition, in striking similarity to the behavior observed in artificially prepared two dimensional MV-15 Josephson junction networks. TI-SAVED NEW Tl-Ca-Ba-Cu-O SUPERCONDUCTOR WITH Tc ABOVE 120 K. H. lhara, M. Hirabayashi. N. Terada. M. Jo, K. MV-13 Hayashi, M. Tokumoto, K. Murata, Y. Kimura, R. Sugise. and T. INFLUENCE OF RADIATrOM DAMAGES ON SUPERCON- Shimomura, Electrolechnical Laboratory, Vmezono. Tsukuba, DUCTIVITY IN XBa2CU3O7_ FILMS, A.A.flikonov, G.V. Ibaraki 305 Japan -- We found a new high-Tc Tl-saved and Ca- Sotnilcov and A.S.Tokarev, I.V.Kurchatov Institute of rich Tl-Ca-Ba-Cu-O superconductor. This Tl-saved high-Tc Atomic Energy - The influence of proton bombardment superconductor is very important in science and technology, with E « 3 - 3.7 MeV in various nedia on supercon- because of its new composition and structure, high Tc and the ducting (SO) and structural properties of Y-Ba-Cu-0 films obtained with the aid of pulsed laser deposi- toxicity and shortage in natural resources of thallium. tion on SrTiOi substrates is investigated. Films of The new Tl-saved superconductor has shown the Tc value of the 1500 X thickness had the initial To - 88.5K. 120-130 K which is almost the same as or higher than that of The dose dependence of T (*t) is studied. o a high-Tc Tl2Ca2Ba2Cu30|o+y (2223) phase. The magnetically It is shown that in the samples investigated Tc drops linearly with increasing irradiation dose and the measured onset of Tc is 122.0 K at its maximum. The rate ol this drop is, approximately, five times composition of the phase is nearly TICa4Ba2CU6O i3ty or quicker, as compared with NbiSn, and there alao takes TlCasBa2Cu6Oi44.y. The Tl content in the new phase is about a place a broadening of the SC transition. The magnetic quarter of that in the 2223 phase. The structure of the phase is susceptibility measurements suggest a reduction of tetragonal with lattice constant of a=5.45 A and c=38.2 A ( or a' the SC phase quantity. = a//2*= 3.85 A and c' = c/2 =19.1 A ). The c-axis is longer than that of the 2223-phase by 2.5 A. Then four or more CuO layers would be responsible for the high Tc of the new MV-14 superconductor. TtMELIM* SPECfROSCOpy IN WIN FILMS WCO/Pb F1MCL STRUCTURES, 5- BenaCfca, V.H. Svistunovt A. Plecenik, S.Chraiiik, The Tl-saved phase was prepared from the starting 3. Levarsky, 5. Ga2i, V. Strbik, S. Takacs, Institute of Elec- materials of TI2O3, CaO and BaCuO3 by firing at 890 °C for 10 trical Engineering EPRC SAS Bratislava.Czechoslovakia, Physico- min and then furnace-cooling in oxygen atmosphere. Other tecftnical Institute of Acad. Set. Ukrainian SSK, Donetsk, USSR conventional process has been studied by changing the starting - Experimental results on electron tunneling into thin super- materials. The preparation of thin film by sputtering and wire conducting films YBa2Cu,Ok in YBCQ/Pti tunnel junctions are re- ported. Thin superconductinp. films YBCO (thickness »0.7 .urn) with Ag-sheath is under going. were prepared by codeposition of V, BaO, and Cu onto single 81 Author Index Abdelmohsen, M.J.: LN-5 Barnes, F.S.: ED-23 Bruzzese. R.: LM-2 Abdelsalam, M.K.: LM-7, Baronavski, A.P.: MC-4 Brynestad, J.-. ML-6, LN-5 Barton, R.: MK-7, MR-1 MN-4 Adam, J.D.: EF-19 Baum, H.P.: ED-37 Buckley, J.R.: ED-2 Adenwalla, S.: MQ-7 Beall, J.A.: ED-31, ED-34, Budai, J.D.: MN-4 Adrain, H.: MK-6 EE-2 Buhrman, R.A.: EB-7, Afanasyev, A.S.: MV-11 Beasley, M.R.: EB-5, EM-5, MK-1 Agatsuma, K.: LN-3, EB-6, ED-33, EF-15, Bumble, B.: EI-6, EK-2, MS-13, MU-5 EM-6, MR-1.MR-2 EN-11 Aihara, K.: ME-4 Beauchamp, K.: MU-1 Burbank, M.B.: ED-30 Aikin, R.M.: ME-5 Bein, D.: MQ-7 Burch, J.: EG-6 Akinc, M.: MV-3 Ben-Jacob, E.: MV-1 Burkhardl. E.G.: EK-1 Akiyama, K.: EN-7 Benacka, S.: MS-12, Butler, K.: MU-3 Akoh, H.: EB-1, EL-12 MV-14 Buttyan, J.: EG-3 Aksenov, P.V.: MG-6 Benjegerdes, R.W.: LA-5 Aksenova, E.N.: MG-2, Berezin, A.B.: MU-2 Cabrera, B.: EE-6, EI-5, MG-6 Bergren, N.F.: MH-1 EL-10 Alba, G.P.: EL-8, EL-9 Berkley, D.D.: MU-1 Caccivio, O.: MV-12 Alcorn, J.: LO-1, LO-2, Betts, K.: ED-30 Cai, X.: MD-5 LO-3, LO-5 Beyer, J.B.: ED-27, Cakauskas, E.J.: EJ-4 Alford, N.M.: EK-6 ED-36, EF-18, EJ-10, Camerlingo, C: EJ-8 Allen, L.H.: EE-4, MO-5, EJ-11 Campbell, A.M.: MH-5, MQ-2 Bhushan, M.: EG-7 MH-6, MT-8 Als-Niesen, J.: ML-1 Bielecki, A.: EI-2 Campbell, I.A.: MO-6 Althaus, R.F.: LA-5 BiSChof, H.: LL-6 Cantor, R.: EH-1 Alvani, C: MM-4 Blamire, M.G.: EG-2, Cao, C: ED-9 Amos, R.S.: EJ-5 EG-5, MU-3 Capobianco, T.E.: MV-8 Andersen, N.H.: ML-1 Bland, R.W.: EL-8, EL-9 Capone II, D.W.: MF-1 Anderson, A.C.: EG-7, Blaugher, R.D.: EC-6, Carelli, P.: EE-7, EF-14, EJ-9, MF-5, MR-4 EG-3 EF-23 Ando, T.: LB-4, LB-5, Blazey, K.W.: MQ-1 Carini, J.: EB-6 LJ-2, MP-6 Blosser, H.: LH-10, LK-1 Carlini, R.: LO-1 Anlage, S.M.: EM-6 Bloyet, D.: ED-7 Carolan, J.L.: LK-3 Antaya, T.A.: LH-10 Boatner, L.A.: MN-4 Carson, J.A.: LF-3 Aoyagi, M.: EA-5, EJ-1 Bochvar, A.A.: MG-6 Carter, W.L.: EJ-4 Apfelstedt, I.:MM-11 Bocko, M.F.: EF-1, EF-2, Casadio, S.: MM-4 Araki, K.: EC-11, ED-35, EL-13, EM-3 Casas, J.: LC-1 EN-7 Bohn, C.L.: MQ-5 Caspi, S.: LA-3, LF-2 Argana, J.: MR-6 Bonmann, D.: LH-5 Castro, R.G.: ME-5, MV-4 Ariga, T: LL-11 Bormann, R.: ML-3 Caton, R.: MQ-6 Askerzade, I.N.: EC-12 Bosch, J.: MK-8 Cave, J.R.: MB-2 Asner, A.: LH-1 Boss, R.D.: MH-4 Celani, F.: MO-6 Autler, S.H.: LC-14 Bossert, R.C.: LF-3 Celikkaya, A.: MV-3 Auzolle, R.: LH-7 Bottura, L.: LJ-4 Ceresara, S.: LM-2 Avitzur, B.: MI-13 Bowen, J.L.: LE-5 Chaklader, C: ED-30 Awschalom, D.D.: EM, Boyce, J.B.: MR-3 Chan, H.: EG-6 EI-6 Bozovic, I.: MR-2 Chan, S.W.: EK-5, MK-5 Braginski, A.I.: EB-3, Chang, C.C.: MR-7 Bai, G.R.: MS-6 EL-4, MU-6 Chang, C.L.: LE-2 Bailey, R.E.: LL-2 Brauer, D.J.: MQ-4 Char, K.: EB-6, MR-2 Bain, R.J.P.: EI-3 Bravman, J.C.: MK-7 Chargin, A.K.: P-4 Bakhvalov, N.S.: EN-14 Bray, S.L.: MB-3, MG-7, Chase, E.W.: MR-7 Cheeks, T.L.: EK-5, MK-5 Bakker, H.A.: ML-2 MH-1.MP-1.MP-2 Chen, F.K.: LE-6 Balestrino, G.: EB-4 Brindza, P.: LO-1, LO-2, Chen, J.: ED-15 Ballentine, P.H.: ED-26, LO-3, LO-5 Cheng, Q.H.: ED-15 MR-6 Brogan, W.T.: MF-5 Cheng, Y.L.: LN-9 Bao, Z.L:ED-9,MS-1, Broholm, C: ML-1 Chew, M.: LO-2 MS-2 Broussard, P.R.: EL-1, Chin, D.: ED-29 Bar'yakhtar, V.G.: ML-4, MO-5, MO-8, MQ-2 Chinone, K.: EH-7 MM-6 Brown, B.C.: LA-3, LH-3, Chisholm, M.F.: EK-2 Barale, P.J.: LA-5 LH-4 Christen, D.K.: ML-6, Barber, Z.H.: MU-3 Brunet, Y.: LL-10 Bardos, V.: LO-3 Brunk, G.: EN-10 MN-4 Barner, J.B.: MV-1 Bruno, A.C.: EH-8, EI-8 Chromik, S.: MS-12, 82 MV-14 Devred, A.: LA-3, LI-2 LN-7 Chumbley, L.S.: MO-3 Dick, B.E.: LE-5 Ferrari, M.J.: EB-5 Chunfang, L: MI-3, MJ-5 Dickson, S.C.: EL-8, EL-9 Fevrier, A.: LC-2, MB-2 Chwalek, J.M.: EB-7 Dieckmann, G.: MS-9 Fietz, W.A.: LJ-5 Cirillo, M.: EF-14, EF-23 Diegel, M.: ED-1 Fife, A.A.: ED-30 Claassen, J.H.: EE-4, Dignan, T.G.: EL-8, EL-9 Filippenko, L.I.: EF-6 EL-1.MK-4, MO-5, Dinger, T.R.: EK-2 Filippenko, L.V.: EH-14 MO-8, MQ-2 Divin, Y.Y.:MV-11 Fisher, M.A.: ED-26 Claeson, T.: EJ-18 Doi, Y: LH-8 Flis, V.S.: MM-6 Clark, A.F.: ED-31 Donaldson, G.B.: EI-3 Fluckiger, P.: EN-12 Clarke, J.: EB-5, ED-33, Donaldson, W.R.: ED-26 Flukiger, R.: MJ-1, EE-1, EI-2 Donati, G.: LM-2 MM-11 Clausen, K.N.: ML-1 Dong, L.: ED-32 Fogle, W.E.: EH-5 Clem, T.R.: EE-4, EH-11, Doolittle, G.: LO-2 Foglietti, V.: EE-7, EF-14, MT-4 Dovgopol, V.P.: MM-6 EF-23 Coffey, K.R.: MF-7 Doyle, W.F.: MH-3 Fokken, A.: LH-7 Colclough, M.S.: ED-3 Dozier, W.: EG-6 Folsom, R.M.: MV-8 Collings, E.W.: MI-8, Drake, R.: EL-3 Foner, S.: MC-3, MC-7, MT-1 Dresner, L.: LI-5 MF-7 Colwell, J.H.: EH-5 Driver, R.: MT-6 Fork, D.K.: MD-3, MR-3 Cooley, L: MG-10 Drung, D.: EE-9, EF-3 Forrester, M.G.: EB-3, Cooper, J.: EJ-20 Dubey, S.S.: MN-2 EL-4 Costa Ribeiro, P.: EI-8 Dustmann, C.H.: LH-5 Forster, M.: LH-5 Costabile, G.: EF-12 Dykaar, D.R.: EB-7, EN-1 Fowler, M.: LO-3 Cottingham, J.: LA-2, Francavilla, T.L.: MC-4 LA-3 Eberhardt, F.J.: MH-5, Frank, D.J.: EJ-15 Cragg, A.: ED-30 MH-6 Freyhardt, H.C.: MC-2, Craighead, H.G.: EK-5, Eckels, P.W.: LI-3, LL-4 ML-7 MK-5 Edeskuty, F.J.: LC-7 Fruchter, L.: MO-6 Crain, J.: MO-4 Edwards, D.A.: LH-3 Fu-Chang, Y.: MI-4 Craybeal, J.M.: MO-4 Egawa, K.: MI-12 Fuchigami, N.: MV-6 Cristiano, R.: EL-7, EN-8 Eidelloth, W.: ED-23 Fujimaki, N.: EA-4 Crocoll, E.: EE-9, EF-3 Eikelboom, J.A.: MC-8 Fujimori, H.: MC-1 Cromar, M.W.: ED-34, Ekin, J.W.: MG-7, MH-1 Fujioka, T.: LC-3, LJ-2 EE-2, EE-3 El-Marazki, L.: LN-5 Fujiwara, Y: MV-9 Cucolo, A.M.: EB-4 Ellis, J.F.: LJ-5 Fukumoto, Y: MS-4 Cui, G.: ED-9, MM-3 Engelhardt, R.: EL-11 Fukutsuka, T.: LC-10 Cukauskas, E.J.: MO-7 Engl, W.: LL-5 Fuller, W.W.: MQ-2 Cunningham, C.E.: EE-6 England, P.: EK-5, MK-5 Funahashi, Y: LF-6 Czipott, P.V.: EI-4 Engler, N.H.: LF-3 Enpuku, K.: EF-13, EH-3, Daeumling, M.: MD-5, EJ-12, MV-6 Gallagher, W.J.: EI-6, MG-10 Eriksen, G.F.: EN-5 EK-2, EN-11 Dahl, P.: LA-2, LA-3 Eriksson, J.T.: LH-13, Gallop, J.C.: ED-10, Dai, Y.: ED-9 LL-9 ED-38 Daly, K.P.: EK-4, MR-5 Ermakov, A.B.: EF-6 Gama, S.: MI-7, MM-12 Danchi, W.C.: EF-7 Eujen, R.: MQ-4 Gambardella, U.: MM-4 Dang, C: EG-6 Evanson, S.: EI-3 Gambino, R.J.: EK-2 Dasbach, D.: LN-6 Evetts, J.E.: EG-2, EG-5, Gan, Z.: MI-2 Daugherty, M.A.: LC-6 ME-2, MJ-2, MU-3 Ganetis, G.: LA-3 Davidson, A.: EJ-15, Eyssa, Y.M.: LC-12, Garber, M.: LA-2, LA-3, EN-9, MK-3 LG-7, LN-5 LH-6, LM-3, MB-1, Dawson, A.M.: LD-5, MG-1 LD-6 Fabbricatore, P.: LM-6, Gardner, R.D.: EI-5 Dayem, A.H.: EK-1 LN-7 Gare, P.: EL-11 Dean, S.O.: LD-2 Face, D.W.: MO-4 Gauss, S.: MJ-1 Debely, P.:MV-12 Fagaly, R.L.: EI-7 Gavaler, J.R.: EB-3, EL-4, de Boer, F.: MH-2 Fan, N.Q.: EI-2 MU-6 Dederer, J.: LG-3 Fang, E.: EC-2 Gavalya, A.: LO-5 Delayen, J.R.: MQ-5 Faris, S.M.: EA-1, EC-7, Gavilano, J.L.: EH-12 de Lima, O.F.: MI-7, EF-17, EL-2, EL-3 Gazi, S.: MS-12, MV-14 MM-12 Fast, R.W.: LF-4 Gazit, D.: MD-3 de Lozanne, A.L.: MU-2 Feigelson, R.S.: MD-3 Geballe, T.H.: MD-3, Del Vecchio, P.: LJ-1 Feldman, M.J.: EJ-5, MR-1, MR-2, MR-3 DeKamp, J.C.: LC-13 EJ-6, EJ-7 Gee, M.: ED-38 Demenko, D.P.: MM-6 Feng, S.: MI-2 Gehan, J.T.: MB-6 de Oliveira, A.C.: ED-12 Feng, Z.X.: LH-12, LN-11 Geller, S.: ED-23 Deutcher, D.: MO-2 Fernandes, P.: LM-6, Gerhauser, W.: MK-6 83 Geri, A.: LJ-1 Hahn, M.R.: MR-2 Herrera, J.: LA-2, LA-3 Gershenson, M.: EH-4 Halbritter, J.: MO-1 Herrup, D.A.: LH-3, LH-4 Geschwindner, D.: MA-7, Haldar, R.: MI-13 Herwig, R.: EE-9 MJ-6 Hate, J.R.: LD-5, LD-6 Hibbs, A.D.: MH-5, MH-6 Gherardi, L: MM-10 Hamada, M.: LC-10 Hida, A.: MT-7 Ghosh, A.K.: LA-2, LA-3, Hamajima, T.: LJ-2 Hidaka, H.: MS-4 LM-3, MB-1, MG-1 Hamanaka, K.: EE-8 Hidaka, M.: EA-3 Gibson, C.R.: LJ-3 Hamasaki, K.: EF-8 Higo, Y.: LC-9 Gibson, E.D.: MI-11, Hamazaki, Y.: EA-5 Higuchi, M.: EH-7 MO-3 Hamilton, C.A.: EA-2 Higuchi, N.: ME-1 Gibson, G.A.: MV-5 Hammond, R.: EB-5 Hikata, T.: MI-6 Gierlowski, P.: MQ-3 Hammond, R.H.: ED-33, Hilal, M.A.: LC-12, LG-7. Giessen, B.C.: MI-13 MR-1 LM-7 Gilbert, W.: LA-3. LA-5 Hampshire, D.P.: MB-5, Hilton, G.C.: ED-21 Ginley, D.S.: ED-36 MP-4 Hinken, J.H.: EF-16 Giovannella, G.: MO-6 Han, B.S.: EN-2, LH-12 Hintermann, H.E.: MV-12 Glowacki, B.A.: ME-2, Han, S.: LH-11, LH-12, Hirabayashi, H.: LF-6 MJ-2 LN-11 Hirano, T.: ED-11 Go, D.: EE-2 Hanasaka, T.: EE-5 Hiyama, T.: LB-4 Goldfarb, R.B.: MB-4, Hanft, R.W.: LA-3, LH-3, Hoehler, A.: MS-10 MC-6 LH-4 Hoenig, M.O.: LB-3, Goldman, A.M.: MU-1 Hansen, J.B.: EN-5 LC-14, LJ-6 Goldstein, M.J.: EE-4, Hao, C.X.: MV-5 Hoff, H.A.: MD-1 EH-10 Harada, Y.: EC-15, EF-21 Hoffman, D.J.: LL-8 Golovanshkin, A.I.: ED-24 Hardy, G.E.: LF-5 Hohenwarter, G.: ED-36, Gomory, F.: MV-7 Hariharan, Y.: ML-5 ED-27, EF-18 Gonczy, J.D.: LF-3 Harmer, M.A.: EK-6, Hohkawa, K.: ME-4 Goodrich, L.F.: MB-3, ME-2 Hondoh, M.: LN-12 ME-6, MP-1, MP-2 Harmston, C: ED-4 Hong, S.: MA-7, MJ-6 Goodzeit, C: LA-2, LA-3 Harris, E.B.: ED-21 Hong, Y.: MQ-7 Goto, E.: EC-15, EF-21 Harrison, K.: LH-10 Honjoh, S.: LC-17 Gottlieb, M.: EL-4 Harrop, S.: ED-3 Hosoda, Y.: MI-6 Gough, C.E.: ED-3, EK-6 Hartmann, R.A.: MC-8 Hosoya, M.: EF-21 Gould, D.: MP-1 Hartung, W.: LN-8 Houwman, E.: EH-1 Gray, K.E..MF-1, MF-4, Hartwig, K.T.: MB-6 Howard, R.E.: ED-34, Haruyama, T.: LH-8 MK-2, MS-11 EK-1 Harwood, L: LO-1, LO-4 Green, J.B.: EG-7 Hsiang, T.Y.: EB-7, EN-1 Hashimoto, K.: ED-19, Green, M.A.: LA-5, LF-2, Hsu, H.S.: MH-3 LK-3, MG-8 ED-28 Hu, Q.: EF-4, EM-4 Green, M.I.: LA-5 Hashimoto, 0.: LH-9 Huang, H.S.: MD-4 Green, S.M.: MD-6, MO-9 Hashimoto, T.: EJ-12 Huang, X.: LC-5, LC-12, Greene, A.: LA-2, LA-3 Hassenzahl, W.: LC-7, LN-5 Greggi, J.: MU-6 LL-7, LN-4, P-2 Huang, Y.: LC-6 Gregory, E.: LA-6, MA-4, Hasunuma, M.: ED-11 Huang, Z.L.: MD-4 MA-5, MB-4 Hasuo, H.: EA-4 Huber, M.E.: EI-5 Gregshammer, P.: MF-4 Hasuo, S.:EG-1, EG-4, Huebener, R.P.: EL-13, Grimson, J.H.: LF-4 P-1 MK-8 Grisel, J.: LF-1 Hatou, T.: MS-7 Hunt, B.D.: EF-5 Gross, R.: EL-13, MK-8 Hauser, B.: ED-17, ED-8 Huson, F.R.: LE-4 Groter, H.-P.: LL-5, LL-6 Hayakawa, H.: MS-7 Hwang, D.M.: MR-7 Gruner, G.: EB-6 Hayashi, K.: ED-13 Hwu, S.J.: MQ-7 Gualco, G.C.: LN-7 Hayward, G.: EI-3 Hylton, T: EM-6, MR-2 Gubankov, V.M.: MV-11 Hazelton, D.W.: MJ-3 Hylton, T.L.: EB-6 Gubser, D.U.: EE-4, MC-4 Heaney, M.B.: EI-2 Gudoshnikov, S.A.: Hebert, D.: EC-1 Ichihara, T.: LB-4 Hedbabny, H.-J.: EJ-3 EH-13 lhara, M.: MS-8 Heiden, C: ED-1, EH-2, Gueraud, A.: LC-2 lijima, Y.: MF-2 Gung, C.Y.: LC-14 MS-10 Ikeda, K.: MM-8 Guo, Z.: MD-4 Hein, M.: MQ-4 Ikisawa, K.: MM-8 Gurney, W.S.C.: EN-4 Hein, R.A.: MC-4 llyichyov, E.V.: ED-25 Gurol, H.: LE-3 Heinemann, K.: ML-7 Imai, K.: ME-3, MI-1 Heinrich, B.: ED-30 Imam, M.A.: MD-1, MD-2 Henning, CD.: LB-1 Hackworth, D.: LG-2 Imamura, T.: EA-4, EG-1, Henry, R.L.: EL-1, MO-7 Hadley, P.: EF-15 EG-4 Haeuser, B.: MO-1 Henshaw, W.F.: MN-3 Inam, A.: MK-5, MR-7 Hagihara, T.: ED-13 Hensler, R.: LG-1 Inomata, H.: EF-9 Hahn, E.L.: EI-2 Herbelot, O.: LJ-6 Inoue, A.: EB-2 84 Inoue, H.: LH-8 MI-13, MJ-3 Konopka, J.: MQ-3 Inoue, K.: MF-2, MI-5 Kao, Z.Y.: LN-9 Kornev, V.K.: EC-12 Ishibashi, K.: EL-12, LF-6 Kapitulnik, A.: EB-6, Korpijarvi, J.: LL-9 Ishida. I.: EA-3 MD-3, MR-1.MR-2 Kosaka, S.: EA-5, EH-7, Ishida, N.: LN-12 Kaplunenko, V.K.: EC-14 EJ-1 Ishigaki. H.: MT-7 Kapoor, R.: MN-2 Koshelets, V.P.: EC-14, Ishigohka, T.: LC-9 Kasai, N.: EH-6, EH-7 EF-6, EH-14 Ishihara, T.: ME-1 Katase, A.: EL-12, LF-6 Kosuge, M.: MF-2 Ishikawa, A.: MT-5 Kato, T: LB-4 Kosuge, S.: MD-7 Ishiyama, A.: LN-12, Katz, J.D.: ME-5 Kotani. M.: EE-5 LL-11 Kaugerts, J.: LA-3 Koyanagi, M.: EH-6, EH-7 Israelsson, U.E.: MM-1 Kautz, R.L.: EN-3 Kramer, G.: EF-3 Ito, H.: EB-2, MS-5 Kawakami, A.: ED-18 Krasnoslobodtsev, S.I.: Itoh, K.: MP-1 Kawamura. H.: EA-5 ED-24 Itoh, M.: MT-7 Kawano, K.: LB-4 KrebS, H.J.: LF-4 Ivanov, Z.: EJ-18 Kawashima, M.: MG-3, Kreilick, T.S.. LA-6, MA-4, Iwasa, I.: ED-35 MI-6 MA-5, MB-4 Iwasa, Y.: LN-3 Kazacha, G.S.: EN-14 Kresin, V.Z.: MO-2 Iyer, N.C.: MN-1 Keene, M.: ED-3 Krischel, D.: LD-1 lyori, M.: MU-4 Kehlenbeck, M.: MC-2 Kruglov, V.S.: MG-6 Kelly, E.: LA-2, LA-3 Kubik, PR.: ED-30 Jackel, L.D.: EK-1 Kephart, R.D.: LF-4 Kucera, J.T.: MO-4 Jackson, H.W.: MM-1 Kerber, G.L.: ED-22 Kuchnir, M.: LA-3, LH-3, Jackson, T.N.: EJ-14 Kerns, J.A.: LI-4 LM-5 Jacobs, E.W.: MH-4 Kerr, A.R,: EJ-7 Kula, W.: MQ-3 Jain, A.K.: EF-11 Kes, P.H.: MF-3, MH-2 Kulkarni, S.K.: ED-4 Jakob, B.: LD-3, MP-3 Ketchen, M.B.: EI-6 Kumakura, H.: MV-2 Jaminet, P.A.: EF-7 Ketkar, M.A.: EJ-10 Kuo, F.:EA-1,EC-7 Janaki, J.: ML-5 Ketterson, J.B.: MQ-7 Kuo, S.M.: LC-4 Janawadkar, M.P.: ML-5 Kettunen, L.: LH-13 Kupfer, H.: MM-11 Jardim, R.F.: MI-7, Khabipov, M.I.: EC-14 Kuriki, S.: EH-9, EK-3 MM-12 Khamas, S.: EK-6 Kurosawa, I.: EA-5 Jeanneret, B.: EN-12, Khanna, S.K.: EF-5 Kussmaul, A.: MV-5 Kim, D.ri.: MU-1 MV-12 Kustom, R.L.: LG-6 Kim, M.R.: MO-3 Jensen, H.D.: EN-6 Kuwano, K.: MT-5 Kim, Y.: ML-6, MN-4 Jiang, C: MD-6, MO-9 Kuwano, Y.: ED-11 Kimura, N.: LH-8 Jiang, H.: ED-9, MM-3 Kuzmin, L.S.: ED-24 Kimura, S.: LC-3 Jiang, J.F.: ED-20 Kwasnitza, K.: LD-3 Jie, B.B.: MS-2 Kimura, T.: MS-8 Kimura, Y.: ME-1 Jin, D.: ED-15 Laabs, F.C.: MO-3 King, C.G.: MA-3 Johnson, B.R.: MU-1 Lacaze, A.: LC-2, MB-2 Kirchgessner, J.: LN-8 Johnson, D.L.: MQ-7 Laibowitz, R.B.: EK-2 Johnson, M.: EB-5 Kirtley, J.R.: EN-11 Kisu, T.: MV-6 Lam Chok Sing, M.: ED-7 Johnson, R.I.: MR-3 Lamm, M.J.: LA-3, LH-3, Johnson, R.P.: LH-3 Kita, S.: ED-14 Klass, U.: EL-13 LH-4 Johnson, R.T.: EL-8, EL-9 Klein, N.: EL-14, MQ-4 Lanagan, M.: MQ-5 Johnson, W.W.: EL-13 Klein, U.: EF-16 Langham, CD.: ED-10, Jones, C.K.: LL-4 Kleinsasser, A.W.: EI-6, ED-38 Jones, H.: MP-1 EJ-14, EK-2, EN-11 Laquer, H.L.: LC-7, LN-10 Jones, T.E.: MH-4 Klimenko, E.Y.: MG-2, Larbalestier, D.C.: MA-1, Jutzi, W.: EE-9, EF-3 MA-2, MA-6, MB-5, MG-4 MD-5, MG-10, MP-4 Kabasawa, M.: MD-7 Ko, H.: EC-3 Larsen, A.: EN-6 Kadin, A.M.: ED-26, MR-6 Kobayashi, T.: ED-14, Larsen, NT.: EL-5 Kado, H.: EH-6, EH-7, ED-19, ED-28, MS-4, Larson, E.: LF-3 LC-9 MU-4, MV-9 Larson, T.M.: MH-1 Kadowaki, K.: MH-2 Kobayashi, Y.: ED-35 Lassiter, S.R.: LO-4 Kahn, S.: LA-2, LA-3 Koch, H.: EH-1 Lathrop, D.K.: EB-7, Kaiho, K.: LN-3, MS-13 Koch, R.H.: EK-2 MK-1 Kamezawa, K.: LF-6 Kohjiro, S.: EH-3 Laumond, Y.: LC-2, MB-2 Kaminsky, G.G.: MC-5 Koinuma, Y.: MS-3 Lebech, B.: ML-1 Kaminsky, P.G.: EM-2 Koizumi, K.: LB-4, LB-5, Lechter, W.L.: MQ-2 Kamisada, Y.: MF-6 LJ-2 Leduc, H.: EF-5 Kampwirth, R.T.: ED-37, Komashko, V.A.: MC-5 Lee, A.: EK-4 MF-1, MF-4, MK-2 Komatsu, T.: ED-18, MI-1 Lee, A.E.: MR-5 Kang, J.H.: MK-2 Kong, Q.W.: LN-9 Lee, AT.: EL-10 Kanithi, H.C.: MA-3, Konopka, A.: MQ-3 Lee, B.: EN-2 85 Lee, G.S.: EC-4, EC-5 Maeda. H.: LC-11. LK-4, McLean. T.S.M.: EK-6 Lee. P.J.: MA-1, MA-2, MI-5, MV-2 McNalford, N.: ME-2 MA-6 Magsig, C.T.: LC-13 McVittie, J.P.: EL-10 Lee, S-: ED-30 Maix, R.K.: LH-6 Mears. C.A.: EF-4. EM-4 Leemann, C.: EN-12, Makida, Y.: LH-8. LH-9 Mecking, B.: LO-1, LO-2 MV-12 Male, AT.: LL-4, MN-1 Meguro, S.: ME-1 Leo, R.D.: EB-4 Male, S.: MH-5 Mehler, M.J.: EK-6 Leoni, R.: ED-33, EE-7, Maley, M.P.: ME-5, MT-3 Mei. Y.: MD-6, MO-9 EF-14, EF-23 Mankiewich, P.M.: ED-34. Meier-Hirmer, R.: MM-11 Lerch, P.: ED-33 EK-1 Mele, R.: MM-10 Lerose, J.: LO-1 Mantone, A.: MA-7, MJ-6 Melnikov, V.S.: ML-4. Leung, E.M.: LL-2 Mantsch, P.: LA-3 MM-6 Leung, M.: EL-1 Mao, S.N.: MD-4 Meng, X.F.: EJ-5 Levarsky, J.: MS-12, Marancik, W.: MA-7 Menovsky, A.A.: MH-2 MV-14 Maritato, L.: MM-4 Meservey, R.: MM-13, Levine, S.: MN-5 Marken, Jr., K.R.: MI-8, MV-5 Levinsen. M.T.: EN-6 MT-1 Messi. R.: MO-6 Levy, M.: ED-37, MQ-6, Markworth, A.J.: MI-8, Metra. P.: MM-10 MQ-7 MT-1 Meuser, R.: LA-3 Lewandowski, S.J.: MQ-3 Marshall, A.: MK-7, MR-1 Michels, P.H.: LL-2 Li, C: ED-9, MM-3 Marston, P.G.: LD-5, Mikhailov, I.G.: ML-4 Li, C.Y.:MS-1,MS-2 LD-6 Miki, Y.: EE-3 Li, G.: MS-1, MS-2 Martens, J.S.: ED-27, Mikkonen, R.: LH-13 Li, H.Q.: ED-6 ED-36, EF-18 Miller, J.R.: LD-4, LI-4, Li, J.: ED-9, MM-3 Martinoli, P.: EN-12, LJ-3, LM-4. MJ-4, Li, K.W.:LH-11 MV-12 MP-5 Li, Q.:LN-1,LN-2 Martoff, C.J.:EL-10 Miller, R.E.:EM-1,EM-2 Li, X.M.: LN-9 Martovetsky, N.N.: LI-1, Millis, R.: MV-3 Li, X.S..LH-11 MG-4 Minervini, J.V.: LJ-4, Li, Y.K.: MV-8 Masarie. K.A.: EE-2 MG-5 Lian, Z.: MI-3, MJ-5 Maslennikov, Y.V.: ED-24, Minowa, N.: LH-8 Lichtenberger, A.W.: EH-13 Missert, N.: MR-1 EJ-5, EJ-6, EJ-7 Massie, L.W.: LL-8 Mito, T.: LH-8, LH-9 Lichtenwalner, D.J.: MF-5 Masur, L.J.: MH-3 Miura. A.: LC-3 Likharev, K.K.: EC-14, Matachi, A.: EK-3 Miyabara, K.: ME-4 ED-24, EJ-19, EN-14 Mathes, H.J.: MO-1 Miyamoto, N.: EC-15 Lilleyman, S.: ED-10 Matlashov, A.N.: EH-14 Miyashita, S.: MI-12 Lin, A.Z.: ED-6 Matrone, A.: LJ-7 Modena, I.: EF-14, EF-23 Lin, C: MM-3 Matsuba, H.: ME-3, MT-2 Moffat, D.: LN-8 Lin, G.Y.: LH-11 Matsuda, M.: EK-3 Mole, C.J.: LL-3, LL-4 Lin, L.Z.:LH-11 Matsui, T.: EF-9, MS-3 Monaco, R.: EF-12, EN-3 Lin, X.: MI-2 Matsumoto, K.: LC-10 Monfort, Y.: ED-7 Liu, F.W.: ED-6 Matsumoto, T.: MI-9 Moodera, J.S.: MM-13, Liu, M.L.: MD-4 Matsumoto, Y.: EL-12 MV-5 Liu, Y.Z.: MD-4 Matsushita, T.: MM-7 More, N.: MG-9 Lloyd, F.L.: EA-2, EF-4, Mattauch, R.J.: EJ-5, Moreau, A.: MQ-7 EM-4 EJ-6, EJ-7 Moreland, J.: ED-31, Lo Cascio, D.M.R.: ML-2 Matthiesen, M.M.: MO-4 ME-6, MV-8 Lobotka, P.: MV-7 Matui, T.: EF-8 Morgan, C: LA-3 Lockhart, J.: EE-3, MG-9 Matusita, K.: ED-18, MI-1 Morgan, G.: LA-2, LH-2 Lorenzen, H.W.: LL-5, Maurer, W.: LD-1 Mori, K.: MI-5 LL-6 Mazur, P.O.: LA-3 Mori, T: MM-6 Lowe, B.J.: LG-1 McAvoy, B.R.: EF-19 Morisue, M.: EC-10, Loyd, R.J.: LE-1, LE-2, McCallum, R.W.: MI-11, EC-11.EC-9, ED-35, LE-6 MI-9, MO-3 EN-7 Lubbig, H.: EN-10 McClay, C.P.: EJ-7 Morita, H.: MC-1 Lubell, M.S.: LD-3, LJ-5 McCubbin, J.: ED-30 Morozovsky, A.E.: ML-4 Lue, J.W.: LJ-5 McDonald, D.G.: EL-5 Morris, G.W.: EG-5, MU-3 Lukens, J.E.: EF-11 McDonald, W.L.: MA-1 Morris, S.: EJ-20 Lumley, J.M.: EL-11 McGinnis, D.P.: ED-36, Moskalik, M.: LH-10 Lundy, R.: LA-3 EF-18, EJ-10, EJ-11 Motowidlo, L.R.: LE-3, Luo, H.L.: MD-6, MO-9 McGrath, W.R.: EF-5 MI-13, MJ-3 Luongo, C.A.: LE-2, LE-3, Mclnturff, A.: LA-3 Mougey, J.: LO-1, LO-3, LE-6 Mclnturff, A.D.: LC-13, LO-5 Luton, J.N.: U-5 LH-3, LH-4, MA-1 Mourou, G.A.: EB-7 McKinnell, J.: MA-1, Moyamoto, N.: EF-21 Madfarlane, J.C.: MT-6 MA-2, MA-6 Muck, M.: EH-1 86 Mueck. M.: EH-2 Nitta. T: LL-1 Pankajavalli. R.: ML-5 Muhlfelder, B.: EE-3, No, K.: MI-11.MI-9 Parodi, R.: LM-6, LN-7 MG-9 Noack, M.A.: MI-11, MI-9, Pashkin. Y.A.: ED-24 Muirhead, CM.: ED-3 MO-3 Pasztor, G.: MP-3 Mukae. K.: MS-3 Noge, S.: ED-18 Paterno, G.: MM-4 Mukai, H.: MI-6 Noguchi, T.: EE-8 Patt, R.: EL-3 Mukhanov, O.A.: EC-13, Nolen, J.A.: LC-13, LH-10 Peacock, A.: EL-11 EC-14 Nordman, J.E.: ED-27, Pechen, E.V.: ED-24 Mullen, K.: MV-1 EF-18, EJ-10, EJ-11, Peck, S.D.: LE-6, LF-5 Muller, G.: EL-14. LN-6, MS-9 Pedersen, N.F.: EN-9, MQ-4 Noskov, V.L.: MC-5 MK-3 Murakami. T.: EJ-13, Noto, K.: MC-1 Pegrum, CM.: ED-2, EJ-17 Nozaki, A.: MI-12 EN-4 Murase. M.: EH-9 Numata, K.: MI-5 Peiniger, M.: LN-6 Murduck, J.M.: EG-6. Peoples, J.: LA-1, LA-3 MF-1 OLarey, P.M.: MA-1 Perot, J.: LH-7 Muroi, M.: MS-3 OMeara, J.: LO-1, LO-2, Peters, C: LA-3, LA-4, Murphy, J.H.: LL-4 LO-3 LF-2 Murphy, M.F.: LK-2 Oae, Y.: EL-12 Peters, M.: EH-1 Musenich, R.: LN-7 Oberly, C.E.: LL-8 Peters, O.: LH-7 Muto. Y.: MC-1 Ochi, K.: EC-9 Petersen, D.A.: EC-1 Mydosh, J.A.: MH-2 Ochi, N.: MS-5 Pfotenhauer, J.M.: LC-5 Mygind, J.: EN-6 Odehnal, M.: ED-2 Phelan, P.E.: LC-4 Ogama, T.: MI-12 Piel, H.: EL-14, LN-6, Nagae, T: LH-9 Oh, B.: MR-1 MQ-4 Nagamori, Y.: ED-13 Ohara, T.: LN-3, MS-13, Pines, A.: EI-2 Naganima, M.: LJ-2 MU-5 Piosczyk, B.: LD-1 Nagano, M.: MS-3 Ohgami, M.: LN-13 Pizzella, V: EH-8 Nagasawa, S.: EA-3 Ohmatsu, K.: MG-3 Platt. C.E.: EK-4, MR-5 Nagata, M.. MG-3, MI-6 Ohmori, T.: LF-3 Plecenik, A.: MS-12, Nakagawa. H.: EA-5. Ohta, H.: EE-5, EF-9 MV-14 EJ-1.EL-12 Okabe, Y.: EB-2, EJ-16, Podney, W.N.: EI-4 Nakagawa, S.: LN-13. MS-5 Poeppelmeier, K.R.: LN-14 Okada, T.: ED-13, LC-10, MQ-7 Nakajima, H.: LB-4, LJ-2 LL-1, LN-13, LN-14, Politis, C: MD-6 Nakanishi, M.: EH-6, MM-2, MM-8 Ponce, F.: MR-3 EH-7 Okada, Y.: EA-5 Ponto, L.: MQ-4 Nakao, M.: MV-2 Okamota, S.: ED-13 Pope, W.L.: LF-2 Nakayama, A.: EB-2, Okamoto, Y.: MN-5 Popov. A.G.: MM-6 MS-5 Okuno, K.: LB-4, LB-5 Portis, A.M.: MQ-1 Nanda, S.: LO-5 Okushiba, H.: ED-13 Pourrahimi, S.: MC-3, Narita, T: ED-35 Olsson, H.K.: EF-22 MC-7 Neal, M.J.: MO-4 Onishi, T.: LN-3, MG-3 Powell. J.C.: MN-1 Nease, B.: MU-1 Ono, M.: LC-3, MD-7 Prodell, A.: LA-2, LA-3 Neeb, N.: MS-10 Ono, R.H.: ED-31, ED-34, Prokhorov, V.G.: MC-5 Nelson, H.H.: MC-4 EE-2, EF-7 Provenzano, V.: MN-3 Neuhaus, M.: EE-9 Onuki, T.: LN-12 Provost, J.: ED-7 Neuhauser, B.: EL-10 Orlando, T.P.: MO-4 Pruymboom, A.: MF-3 Newitt, D.: EI-2 Orr, J.R.: LA-3 Przybysz, J.X.: EC-6, Ni, B.: MM-7 Ortoli, E.: LG-3 EG-3 Ni, J.: MS-6 Oshima, M.: ME-4 Pshentsova, N.P.: ML-4, Nicol, E.T.: LF-3 Osofsky, M.S.: MD-1, MM-6 Nielsen, M.: ML-1 MD-2 Pullano, M.: EE-7 Niemann, R.C.: LF-3 Osterman, D.P.: EL-2, Purcell, J.R.: LE-4 Nigro, A.: MS-11 EL-3 Purpura, J.W.: EE-4, Niki, K.: MT-5 Ozeryansky, G.M.: MI-13, MT-4 Nikonov, A.A.: MV-13 MJ-3 Nikulenkov, E.V.: MG-6 Oadri, S.B.: MO-7 Ninomiya, A.: LC-9 Pace, S.: EB-4, EF-23, Qian, X.: LG-6 Nisbet, R.M.: EN-4 MO-6 Qin, J.: EF-13 Nisha, M.: LJ-2 Padamsee, H.: LN-8 Nishi, M.: LB-4, LB-5, Pagano, S.: EF-12, EN-8 Rachford, R.J.: MQ-2 MP-6 Palevski, A.: MK-3 Radcliffe, W.J.: ED-10, Nishijima, S.: MM-2, Pan, S.K.: EJ-7 ED-38 ED-13, LC-10, LN-13, Pan, V.M.: MC-5, ML-4, Radhakrishnan, T.S.: LN-14, MM-8 MM-6 ML-5 Nishizawa, M.: EC-9 Pande, C.S.: MD-1 Radparvar, M.: EA-1, 87 EF-17, EL-2, EL-3 Sakai, Y.: MM-8 Shen, T.Z.: MS-6 Radparvar, R.: EJ-2 Sakaiya, S.: ED-11 Shen, Z.: MI-2 Raicu, E.: EF-20 Sakakibara, Y.: LF-6 Shepard, K.W.: MQ-5 Raider. S.I.: EN-11 Sakaniwa, K.: LC-9 Shibui, M.: LJ-2 Ramesh, R.: MO-9 Salathe, D.G.: LH-6 Shibuta, N.: MI-6 Rangaswany, S.: MI-13 Sales, B.C.: MN-4 Shimada, M.: LJ-2 Rath, R.C.: MR-6 Sampson, P.L.: ME-2, Shimamoto, S.: LB-4, Raveau. B.: ED-7 MU-3 LJ-2, MP-6 Rayne. R.J.: MN-3 Sampson, W.: LA-2, LA-3 Shimizu, H.: MV-2 Reardon, J.D.: MI-13 Sampson, W.B.: LM-3, Shimizu, N.-. EC-15, Rechen, J.: LA-3 MB-1, MG-1 EF-21 Reiger, M.: EF-10 Samuelsen, M.R.: EN-5 Shinada, K.: EE-5 Remsbottom, R.: MA-1 Sanada, Y.: LC-3, LJ-2 Shinbo, Y.: MD-7 Repp, J.: LG-2 Sandell, R.: EC-5, EG-6 Shinoki, F.: EB-1 Richards, G.L.: MB-6 Sandstrom, R.L.: EI-6, Shintomi, T.: LH-9 Richards, L.: MD-1 EK-2, EN-11 Shiraki, H.: LJ-2 Richards, P.L.: EF-4, Sarma, B.K.: ED-37, Shitov, S.V.: EF-6 EL-6, EM-4 MQ-6, MQ-7 Shoji, A.: EA-5, EJ-1 Richardson, S.A.: MV-4 Saslry, G.V.: ML-7 Shou-Tian, C: MI-4 Ried, D.L.: MB-4 Sastry, V.S.: ML-5 Shu, Q.S.: LN-8 Rifflet, J.M.: LH-7 Sato, A.: LK-4 Shutt, R.: LA-2, LA-3 Riggs, C: LO-2 Sato, M.-.EC-11. LB-4 Siddall, M.B.: LM-1 Rinderer, L: LC-1 Sato, R.: MI-1 Signorelli, E.: MS-11 Rizkalla, M.E.: MV-10 Sato, T.: LB-4 Sikkenga, J.: LK-6 Robbes, D.: ED-7 Sauvageau, J.E.: EL-5 Silvennoinen, R.: LH-13 Robertazzi, R.P.: EM-5 Savo, B.: EB-4 Silver, A.H.: EC-5, EG-6, Robins, K.E.: LM-3 Sborchia, C: LD-3 EK-4, EM-2 Robinson, Q.: MQ-7 Scanlan, R.: LA-3 Silver, R.M.: MU-2 Rocha, R.: LE-4 Scanlan, R.M.: LA-5, Silvestrini, P.: EL-7, EN-8 Roeland, L.W.: MH-2 LA-6, LF-1, MA-3 Simon, R.: EE-2, EK-4 Roemer, G.: ED-30 Schaper, W.: MC-2 Simon, R.W.: EG-6, EL-1, Roesler, G.: MV-5 Schenstrom, A.: ED-37 EM-2, MR-5 Rogalla, H.: ED-17, ED-8, Schermer, R.: LA-3 Singh, A.K.: MD-1, MD-2, EJ-3, MO-1 Scheuermann, M.: MK-3 MN-3 Rogers, C.T.: EK-5, MK-5 Scheurer, H.: MM-11 Singh, S.K.: LL-3, LL-4 Rollins, R.W.: MT-1 Schilder, J,: MS-12 Sizemore, J.: MK-7 Romani, G.L.: EH-8 Schilling, O.F.: ED-12 Skocpol, W.: ED-34 Romano, P.: MS-11 Schindler, J.W.: MH-4 Skotheim, T.A.: MN-5 Romanovskii, V.R.: LC-8 Schmitt, P.: MK-6 Smathers, D.B.: LM-1. Schneider, W.: LA-2, Rosatelli, R.: LJ-7 MC-6 Rosenthal, P.: EB-5, LA-3 Smatko, V.: MS-12 ED-33, MR-1 Schrodt, D.J.: MN-3 Smith, A.D.: EG-6, EM-2 Rossi, S.: LM-2 Schurr, J.: EL-14 Snigirev, O.V.: ED-24, Roth, R.W.: LN-6 Schwartz, D.B.: EK-1 EH-13 Rowell, J.M.: P-3 Schwarzmann, E.: ML-7 Snortland, H.J.: EM-6 Royer, R.: LA-3 Schwenterly, S.W.: LI-7, Snow, E.S.: EL-1 Royet, J.M.: LF-1 LJ-5 Sobolewski, R.: EB-7, Rozen, J.R.: EI-6 Sears, J.: LN-8 EN-1, MQ-3 Rubin, D.: LN-8 Sekine, H.: MI-5 Soderlund, L.: LH-13 Rudman, D.A.: EJ-9, Sekula, S.T.: ML-6, MN-4 Sodtke, E.: EH-2 MF-7, MO-4 Selim, R.: MQ-6 Soldatov, E.S.: ED-24 Ruggiero, S.T.: MV-1 Semenov, V.K.: EC-12, Somekh, R.E.: EG-5, Russek, S.E.: EB-7, MK-1 EC-14, EH-13, EJ-19, EL-11, MU-3 Russo, M.: EJ-8 EN-13, EC-13 Song, J.: ED-15 Russon, C.J.: MH-3 Seppa, H.: ED-5, EH-5 Sotnikov, G.V.: MV-13 Ryhanen, T.: ED-5 Serdyukova, S.I.: EN-14 Soulen, R.J.: EH-5 Rylov, S.V.: EC-13 Serpuchenko, I.L.: EC-14, Souza, J.: MO-4 EF-6, EH-14 Spadoni, M.: LM-2 Sacchetti, N.: LM-2 Seuntjens, J.: MD-5 Spargo, J.: ED-22, EJ-20 Sadakata, N.: MI-10 Shadrin, P.M.: MV-11 Sparvieri, N.: MO-6 Sadananda, K.: MO-1, Shao, K.: ED-9 Specking, W.: MJ-1 MD-2 Sharifi, F.: EH-12 Spielman, S.: MR-1 Saggese, A.: EB-4, MO-6 Shchedrin, V.D.: EC-12 Spivakovsky, V.B.: MM-6 Saha, A.: LO-3 Sheinberg, H.: MT-3 Sreedharan, O.M.: ML-5 Sakae, T.: EL-12 Shejun, D.: MI-3 Srivastava, P.K.: MV-12 Sakaguchi, Y.: ED-28 Shen, N.X.: ED-16 Stanek, P.W.: MV-4 Sakai, S.: EC-8 Shen, S.S.: LD-3, LD-4 Starch, W.: MA-1 88 Steeves, M.M.: LB-3, Talvacchio. J.: EB-3. Uchikawa. Y: EE-5 LC-14. U-6, MC-6 MU-6 Uchiyama, F.: MU-5 Steinbeck, J.: MR-4 Tamura, H.: EA-4 Uehara. M.: MV-2 Stern. J.A.: EF-5 Tanabe. H.: ED-14 Ueminami, K.: MM-8 Stewart, M.: ED-10, Tanaka, A.: LJ-2 Ullmann, B.: ML-7 ED-38 Tang. H.T.: LN-9 Umeda. M.: ME-1 Stirling, G.: EI-3 Tang, J.: MM-5 Urata. M.: LC-11.LK-4 Stone. M.E.: LF-4 Tang. L: ED-6 Urbina, C: EE-1 Strait, J.: LA-3 Tang. Y.S.: ED-20 Straughn, B.L.: EK-1 Tang, Z.D.: ED-20 Vaccarone, R.: LJ-7, Strayer, D.M.: MM-1 Tao, Y.: ED-32 LM-6 Strbik, V.: MS-12. MV-14 Tateishi, H.: MG-3, Vaglio, R.: EB-4, MS-11 Strieker, D.A.: EL-8. EL-9 MS-13 Van de Klundert, L.J.M.: Strom, U.: EL-1 Tavehelidze, A.N.: ED-24 MC-8 Strum, M.J.: MJ-4, MP-5 Taylor, C: LA-3, LA-4 Van den Berg, J.: MH-2 Stumpf, R.: MK-6 Taylor, C.E.: LA-6, LF-2 Van der Beek. C.J.: MH-2 Suenaga, M.: MN-5 Tazoh, Y.: ME-4 VanDuzer, T.: EC-1, Sugahara. M.: EJ-13. Tedrow, P.M.: MM-13, EC-2, ED-29, EF-20 EJ-17 MV-5 Van Harlingen, D.J.: Sugimoto, M.: MI-10 Terajima, A.: LF-6 ED-21.EH-12 Summers, L.T.: LM-4, Tesche, C: EE-3 Van Sciver, S.W.: LC-6 MJ-4. MP-5 Tesche, CD.: EN-11 Vasilenko-Sheremetiev, Sun, J.2.: MD-3 Theriot, E.D.: LF-4 M.G.: ML-4 Sun. K.J.: MQ-6 Thieme, C.L.H.: MC-3, Vasiliev, A.V.: EH-13 Sutton. E.C.: EF-7 MC-7, MF-7 Veca, G.M.: LJ-1 Suzuki. E.: MF-6 Thier, N.: MM-9 Vecsey, G.: LD-3 Suzuki, H.: EA-4 Thomas, G.: MO-9 Vedrine, P.: LL-10 Suzuki, K.: EC-10 Thompson, J.R.: ML-6, Venkatesan, T.: EK-5, Suzuki, M.: MT-5 MN-4 MK-5, MR-7 Suzuki, T: MD-7 Thompson, P.: LA-2, Verhaege, T.: MB-2 Svensmark, H.: EN-5 LA-3 Verhoeven, J.D.: MI-11, Svistunov, V.M.: MV-14 Thuns, P.: LN-6 MI-9, MO-3 Symko, O.G.: ED-4, EN-2 Tien, C.L.: LC-4 Villegier, J.C.: EJ-2 Syphers, M.J.: LH-3, Tixador, P.: LL-10 Volkov, A.F.: MV-11 LH-4 Tkaczyk. J.E.: MM-13, von Goeler, F.S.: MA-5 MV-5 Voronova, M.A.: EN-13 Taber, M.A.: EI-5 Togano. K.: MV-2 Vrba, J.: ED-30 Tachikawa, K.: MD-7, Tokarev, A.S.: MV-13 Vyshenskii, S.V.: EC-13 MF-6, MI-10, MP-1 Tollestrup, A.V.: LH-3, Vystavkin, A.N.: EC-14, Tada, E.: LB-4 LM-5 EF-6 Tahara, S.: EA-3 Tolpygo, S.K.: ML-4 Takacs, S.: MV-7, MV-14 Tomlinson, E.J.: MU-3 Wachi, Y.: LC-3 Takada, S.: EA-5, EB-1, Tompklins, J.: LA-3 Wada, T.: LK-4 EJ-1.EL-12 Tonouchi, M.: ED-19, Wada. Y.: EA-3 Takahashi. K.: ME-1, ED-28, MS-4. MU-4 Wagner, G.R.: EF-19, MV-2 Torriani, I.: MI-7, MM-12 MN-1 Takahashi, M.: EB-1 Torrioli, G.: EH-8 Wagner, M.K.: MR-5 Takahashi, Y.: EE-5, Toth, A.: ED-22, EJ-20 Wakata, M.: Ml-12 LB-4, LB-5 Tracey, J.E.: LJ-6 Wald, L.: EI-2 Takahasi. Y.: LJ-2 Track, E.K.. EF-17, EL-3 Walk, P.: MO-1 Takahata, K.: ED-13, Tran, H.: ED-30 Walker, L.H.: LE-5 LC-10, LN-13. LN-14, Tretiatchsnko, C.G.: Walker, M.S.: LE-3 MM-2, MM-8 MC-5 Walsh, T.E.: LE-1, LE-5 Takahata. M.: EE-5 Tsaur, B.-Y.: MR-4 Wan, K.L.: EF-11 Takai, Y.: MS-7 Tsuda, K.: MS-3 Wanderer, P.: LA-2, LA-3 Takami, T.: EE-8 Tsuge, H.: EA-3 Wands, R.H.: LF-4 Takano, S.: MI-6 Tsuji, H.: LB-4, LB-5, Wang, F.: LN-1, LN-2 Takao, T.: LC-17 LJ-2 Wang, F.R.: MS-2 Takata, M.: ED-18 Tsukamoto, K.: MU-5 Wang, S.: ED-20, ED-9, Takayasu, M.: LC-14 Tsukamoto, O.: LC-17 MM-3 Takeno, K.: EL-12 Tulin, V.A.: ED-25 Wang, S.L.: MS-1, MS-2 Takeoka, A.: ED-11, Turck, B.: LB-2 Wang, S.Z.: MS-1, MS-2 MT-5 Turowski, P.: LD-1 Wang, Z.: EF-8 Takeuchi, H..- EH-9 Tuzel, W.: LO-2, LO-4, Wang, Z.K.: LN-9 Takeuchi, K.: EB-2, LO-5 Watanabe, K.: MC-1 EJ-16, MS-5 Twerenbold, D.: EL-11 Weber, H.W.: MF-4 Takeuchi, T.: MF-2 Weber, J.: MV-12 89 Wei, C: MI-2 Yang. S.Z.. ED-15, ED-16 Wfei. T.: MS-6 Yazawa, T.: LK-4 Welch, D.O.: ML-2 Ye. P.: LN-9 Wellstood, F.C.: EB-5. Ye, Z.X.: LN-9 EE-1 Ye. Z.Y.: MS-1 Wenger, S.: LH-1 Yeh, W.J.: ED-4, EN-2 Wengler. M.J.: EF-1, Yin, D.: ED-9 EF-2, EM-3 Yin, D.L.: MS-1, MS-2 Westerveld, J.P.A.: ML-2 Yongzai, Y: MI-3 Whitaker. J.F.: EB-7 Yoshida, K.: EF-13, EH-3, Whiteley, S.R.: EA-1, EJ-12, LB-4, LB-5, EC-7 MV-6 Whitlow, G.A.: MN-1 Yoshikawa, N.: EJ-13, Whitmore. S.: EM-6 EJ-17 Whittaker, E.A.: EM-2 Yoshiwa, M.: LN-13, Wiech, U.: MM-11 LN-14 Wiegert, R.: MQ-7 Yoshizaki, K.: MI-12 Wiener-Avnea, E.: ED-22 Yoshizako, Y: ED-28, Wiesenfeld, K.: EF-15 MU-4 Willen. E.: LA-2, LA-3 Young, B.A.: EL-1O Williams, J.E.C.: LK-5 Yu, D.: MM-5 Williams. K.E.: MO-4 Yu. J.L.: MD-4 Willis, J.O.: ME-5, MT-3 Yu, X.: ED-20 Wilson, C.T.: LJ-5 Yu, Y.J.: LN-9 Wintree, W.P.: MQ-6 Yurek, G.J.: MH-3 Wintenberg. R.E.: LJ-5 Yurke. B.: EM-2 Winzer, K.: MM-9 Yuyama, M.: MF-2 Wipf, S.L.: LC-7, LH-6, LN-10 Zakosarenko. V.M.: Wire, M.S.: EK-4 ED-25 Wolf, S.A.:EE-4, EL-1. Zalek, S.: MA-7, MJ-6 MC-4, MO-2, MO-8 Zbasnik. J.: LA-4 Wolf, T.: MM-11 Zeigler, J.: LE-4 Wolff, S.: LH-7 Zeitlin. B.A.: MA-3, MI-13, Wong, J.: MA-4, MA-5 MJ-3 Wong, R.L.: LI-4 Zelensky, G.K.. MG-6 Wong, S.C.: EJ-9 Zeller, A.F.: LC-13, LH-10 Wong, T.: MN-5 Zeng, X.: ED-9 Woody, O.P.: EM-1 Zerobin, F.: LH-1 Wordenweber, R.: ML-7 Zhalko-Titarenko, A.V.: Wu. K.-Y.: ED-23 ML-4, MM-6 Wu. P.H.: ED-15, ED-16 Zhang, D.: MM-5 Wu, X.D.: MK-5, MR-7 Zhang, H.: MI-2 Wu, Z.Y.: MD-4 Zhang, J.: MI-2 Zhang, K.S.: MD-4 Xi, Y.: MI-4 Zhang. Y.: ED-1, LN-11 Xie, K.X.: ED-20 Zhang, Z.N.: EF-1, EF-2 Xie. L.M.: MS-6 Zhao, X.: MD-4 Xin-Shan, L.: MI-4 Zhao, Z.: MQ-7 Xinhang, C: EO-32 Zhaoling, Y.: MI-3. MJ-5 Xu, M.F.: MQ-6, MQ-7 Zheng, D.J.: ED-4, EN-2 Xu, W.: ED-18 Zheng, Y: ED-37 Xue, C.L.: LN-9 Zhou, R.: MA-7, MJ-6 Zhu, J.: MI-2 Yahara, Y,: MT-2 Zhu, X.: MI-2 Yamada, Y.: EE-5 Zhuravelev, Y.E.: EH-14 Yamamoto, A.: LH-8 Zichy, J.A.: LD-3 Yamamoto, H.: MI-5 Zimmerman, J.E.: EK-4 Yamamura. H.: LB-4 Zimmermann, I.: MC-2 Yamanoi, Y.: LH-9 Ziqiang, S.: ED-32 Yamaoka, H.: LH-8 Zorin, A.B.: EJ-19 Yamashita, T.: ED-18, Zurbrugg, C: EN-10 EF-8, LC-10 Yamashita, Y: MM Yan, L.G.: LH-11, LN-9 Yanagisawa, T.: MU-5 Yand, Y.: MS-9 90