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LA-UR- 92-1355

Title: ANT IPROTON DRIVEN F1lCROF 1SS ION-ll!S ION ON CLOSER IN SPIKTION

LJHx+-92-1355

IE92 013527

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LosAlamos NATIONAL LABORATORY

LOSAlmnos NMond Lnbofalow, an Mlrmativo dorvqual Owortunw ●n’dw, ISowwd @ Ih. UWWOW d cdlfotnla tot Ih. Us hwfiff~nl of En.fov undw conkocl W 7405 ENG 30 W acwptmx of thm wlwk, Iho pubhtwt focagnwos that M. U S Govomwnt mtams a MMBCIWW Ioydly hw Mans. 10 publish or roprodua Iho publmhd form of thmcwwn.mori, or 10●llw othofs to do ●, lot U S (30vornrwnl purpoaoa Tho Loo Alwnon NaIIwml labomtory rquosta Ihd tho publmh.r lclofflltf Ihlo artlclc so worh pdomud under M ouqwxs of the U 9 Dopwtrrwl d Enorgy % lwnNO O.nln$ ANTIPROTON DRIVEN MICROFISSION-FUSION ON CLOSER INSPECTION

R.R Wienke AppUed Tbewetlcat Pbyslcs Division LAMAlasnosNational Laboratory Los Alamos, N.M. 87S45 (S05) 667-1358

ABSTRACT

A closer Ioak al the energelics of antiproion in real sysiems, coupled 10 h.ydro@namics, nwerials srrenglh, mawpor!, equations of slate, and relaled inleraclion$ is necessary 10 assess ultimate viabilip. The systema!ics of amiprolon microjission-fu sion are \he subject of \his anal,ysis, as well us technology constraints.

INTRODUCTION

PotciM schenws for employing antiprolon- annihilation as a driver for space propulsion, power gen- eration, condensed rrumcr physics cxpeMw’!Ls, biomedical treatment, and others become rnorc interesting and viahlc with the advent ot’ pcnlable storage tsaps (Penning) ad rclaled prod-of-principle sIor*ge experirswnts al LEAR recently. In the fission arena, mimspcllet expxi.mcnLs at UscPhillips LAordtory SHIVA facility (imploding solid liner) arc planned to study anti proton annihilation on uraniurm by injecting some 107 anti from a porl - able over approximalcl y IO nsec, Ttw (Jcsign and construction of this tral~ hi+vc been undctlitkcn tsy Los Alarms Nationiil Laboratory, Correspondingly, nurrumus cakmliuions supporting t.bc iipplicahon ot’ antiproton cbivcn energclics have thus hccn proposut and rcporled. A clo.wr look at the cncrgclics of armproton annihilation in reiil systcnm, coupled to hydrodynamics, nwtcnids slrcngth, p i‘1’ rsimspofi, equatmns of state, and rclulcd intm+c. Y.’Ii ‘ uons is nccessiiry 10 assess ultmuitc viahihly. Tlw systcmalics 01 armproion nticrotissl[~ll-thslol] arc Ihc sutqcct of tlw pruwntation, as WCI1us Icchnology constrains. In reviewing Iitcral’m!, il iippciils thiil eslimalcs of antiprotnn encrgclics arc oprirmsliu, appamnlly rm)lut m malcrial equations-of-waw, ncuwomcs, and bum r.rciimmmwcmployd in analyses. Anliprotoo iinnihiliilion in rmtlcr is onc of the most cncrgctic rwwions ohsmvcd routinely in high tncrg) ph)- !dcs, some 1X7 (;cV per annihiliition. In actinidc fuels, soch us phmmium MINI urismum, anliprolon wsnihih+lmn al the nuclear surfucc also induces tkwion wilh very high probability and numlwrs of nculruns, The corrduniition of IIW two cffecLs mighl hc cxpxtcd 10 inilialt! and dnw! Wdon-t’usion in hyhrsd or sirnplc systcrns, In MMIIOII 10 tlw encrgct.ks d’ annihiltitiun, the transpofi of anliprolons through nwttcr, UIIIII tlwy arc slopped and cupturwl on Uw The kind .s of nculruns in highly comprcwcd mislunul htis hum rdudicd ~&%;lH’P’I nlu$t ti considcrcd, and Ibc conclusions htivc tirncly bcwina on unliprolon dnvcn sy!utmv, namely Ihal vhlually impossi- ble c&rqwemcsJ stales of arc rcquirt!cl for him. Similarly, Ihc ntiluru ot iumihilislmn tilsu rcquh’cs trnrIsporrInII antiprotons in firmly fashion through maucr, so M 10 SJISINWIU t.lw annihiltitlon Iwutrons unifomd) in the Milt region.

ANTIPROTON” FIS!$ION

Taking the phm+riggcrcd CERF$data of Angclopmlos’ shown in FigIIru 1, wc have conmIcIcIJ a fission mulligroup cross scctio tahlc [or mrliprotom, 10 tm used in c91culiWons of t]mhm, fudon. ml fission. I fusion encr@ctics. The spectnnm hwludcs two wnqnmcnl Maxwell-Bolwsnann diswiltutbrss, wcounting for diru’1 md evapmtion IXOCCIISeS,plus a Walt dintrinution, accounthi$ for Ilwion. SCVCIIfitPBSSMCICSS, (t7,#JlT,~J,F:j),k%thefom A 4E 1’2 exp[-(E, +E )/Tf ] —= Y(E)= ~ a, — exp (–E/Ti ) + UJ sinh (21J,:’ZE1’2 / Tf ) , (1) a~ nT,3 i-d,r [1 [ (nE, TJ)”2 1 with i denoting direct, evaporation processes, and ~ fission. Ille T are characteristic temperatures, while the a are numbers of normalized 10, ~ (3,=;, (2) i-d, r,.f and Ef is a fissiou tier energy. Specifically, we have Mid, ;= 13.6 ,

ad =4.39 , T~ = l12,8MeV ,

a, = 1.53 , T, = 10,3 MeV ,

a, = 7.68 , T, =2,3 McV , E, = .727 MPV , (3) using a Lcvenherg-Marquardl non-linear Icasl squares algoriIhm. MuMgroup (g) fission fractions, Z, uscti in .$n and Muntc Carlo neutron transport CMIM, ranlxcsrimatcd, l“, (4)

Figure 1 contrasLs tlw fission spectra (crmvcnicnlly nrsrmiilimd) for neulrons and antiprolorss iucvden! 011 U13N. Clearly Ihc anliprolon spectrum is more peaked al hlghcr cnergws than the nm.mon spectmm,

ANTIPROTON” TRANSPORT

3,4 A mulligmufr Irthniquc 10I Iranspmlinp chtirged particks has km dcwlopul, and anKNnIIS to dclh]lng a downscathmxl cross SLMIOI1, 0’, over many cln!rg) gruups. (j, in lc!m~%ot’Ihc UqNXirrwnlirl (or Iheorclicdl) slopping power. dli / ils, fur L tlw energy iind s Ihc path Icngth II h~t twcn cmplnycd in apphcaliorrs (Ion tn!isrm, ICF. u md prolon energy dcpmliun in I’IIUIS,CL) wllh suwcss II Is appropriistc i’or Irimspomng iinllprolons III nkstwbsls, when cnc:gy dcposiuon and range iiru m!ccss~ In cah’uliihons l“oril~~%tcs,lwstiprotom, USIMII) with knwtlc cncr. gio in ltrt kA; range.

numtmritrg sonk .3t), or mom, for parriclcs hl Uw kW FHIIW, Inlcgrals over mrcrgws can Iw camut OUI nud-poinl 10 midpoint wow groups, #, The mnq) cncr~) dqMwul in 4 UCII, rE, lx Ihl’ lllfttrcml’ or [h?ullcll’Curmnl nlfl(m nunJs ouIftow, J~”, Ilnkx group cncr~y, l.’?,

c, ~ /:, J;” ,

(7) Figure L Comparative Flsslon Spectra [n UD~.

150

,.,, ...’ 125 LEGEND 100 .-+%iR--...,,...,,,,.,.,,,,,,.,..,.,...... ,,.,,,,

?5

50

“,, ..,, 25 ,,, . . ‘- .,.., . ...,

0 I I 012345678 9 10 II 12 13 14 15 energy –– mev

F@H % Antlprolon Slopplng Pbwen [u UUB.

10 I I 1 I

9 LEGEND tem~=10 ev ,,. 8 Cv.. ~~~~~~cmp.yi(!v,Crn,p,: ,,.,,’,,’ ...... ,, ,.... 7 ,.,.,,,,,..,, .,,!,,,, 6 ,., ,,,,. ,.,!,,’” .,’ 5 ,..,’ .,, 4 - 3

2

1 ...... ’

...... ”.””” 1 I .~ 0 b-- ● !)() o 10 20 :)() 40 k(w (8) #-l Groups are defined over a range of irwiderrl kinetic enerfl down to Ihermal energy, in decreasing group size accord- ing tOEq. (6). 3,9 ArNiproton stopping powers m aclinides can k written in general form (kAf/cm ),

aE nAZ2 Cm(SC)-(2Kfn’ 1 exp (-lc~) , (9) % = 1“303x10-’9 [ AE ][ 1 for Z and A the charge and atomic mass unit of stopping material, K lhe antiproton energy E, scaled by lempera- hue, T,

(10)

A & Coulomb cutoff as a function of lemrm!ralurc and energy, erf Urc error function, aml n k slopping pamcle nornkr dcnsity (ions, ). Compiiru~ to protons, anli~~otolis am slight 1y Iwrgcr-rmged. Olw IoIIsl~, ail) seI of arlliprolon rangcawrgy dara could bc Ih’tcd in similar functional Iorm. Figure 2 dcpicls l.hc clr!!rron slopping! power for antiprotons in normal dcnsily UUH, at wmpcrahrrm 0110 CV, 100 W, and I keV. Such range of enq?ics might be CXPCIUI in pon.ahlc trap irpplicalirms.

SYSTltMATICS

Some calculalions5’7’8 ’1’ of ticrollssiol].lllsio[l” In apl)lwations have been repxlcd, and a discussion of sys- Iernatics is illuminating. RCSUIIS,exhitriling tolal fuel tium in I gr 10 10 gr taqxls, ar’u nol realislic, considering drive pressure, compression, final density, nurrslwrs of initialing anliprolons, and iission and fusion neumon output. Related calculations unrkrwsre tic efl”ixm of viisymg antiproton ignilion Ievcls for induced fission-fusion chains al high dcnsily, suggesting only some 107 miliating anhprotons. To cnhiincu yield M a funclron of ant.rproton igniuon Icvcl, wc wlainly can:

( I ) incrcasc crmqmcssion: (2) incrcasc Iissilc miss: (3) employ coml%atmos: lmI opIimImd dc:~ifzn(minimum iintipro[on. drive prusmrc. fuel mass) must he pursuu.1 w Uhlu consmunts ol prcwnl Icchnolog), ptirlicularl} cumprcssions and nomhcrs of wlliprolons nuccssirr) 10 drl$c a cnllctil sys~. II. The high comprrxsions cilrd am \ u~ dlfliuult within cxislmg lculmologIcs, Crxmnon rcaclor nculromcs corks sllggcsl lhirl smne 1011 in~l.ialmg armprotons arc rcqulsm 10 dnvc sllch pcllcI conilguriihoos.

Ilw crwntmition d’ high Ilssion protushillly and rwulron mulhpliclty IS still wrwliw 10 iniliw uncl drivu Ilssion-limm Insmlplc or hylwrd sywnw possdll) small sysums twwauw Ihc mlllauon Imw IS shon [ 10 n.w L ihc resohmg ncum)n iotmslty is hllrh und Iinwsihlc, imd the iirsl burst of annlh!liilmn nculrons slam the chi+ln rcwlmn al Ihrw gmrmhons. Syslcms cmpluying antiprotom WIII WIWSS highur Iu’isl ncumm Inlcnsitw wnpamd lo w IICWOII gcncrtitors UOIIUIIWII!,~vaIld_dc. coltsdurulg hwlors such as tinl IprrNon hum SIN, tlut out ol rhc trap, wd pamclc rwrgc. Shells Id Ilmwwlvcs !o atlllpro[on milimon, nxalllug Ilw shorl ranflt ot twn kcV antiprutons (alwul 50 mimrnrs al 50 k# ), Anl@olon wrnihilirlmn also Icmls iwclt to mall (cqwullh) wwmhlws, Ilw goal of any capsule dcviuc i~ IO Initialc !wlf-proptigaling nuclwr rciiclions In a wwrll amount ul’ mwnirl, The malcriirl is compn’swl to hqrh den. wily, and hs hwliti should nuinluin Ihc high dcush~while ruirclmns wcur. Om’ chisllmgu is lo find prticllcal rndhmls or speeding up W uucluar reacIkms. w Ihtit I’OCIhum is rw I* CI’IICMIII) pltiytd oll WIIISI dwwemhly. R@d Wkm hrltitilion is OIICsuch rwhod, ahrg with th~ addmonal Icwrqrr of hcainl~ of Ilwmmrmclwrr fuel, Ihcn!hy n“duchq wnrc of Ihc gas mrrprcwou requhwmm,

Ovcr a whlc range of Iar#cl sbcs, I gr to 100” gr appmxinmtcl), Iwo imprmtinl faclors, wilicalit) and dismw!mhly, sflix’1 IMIOII (wI ultmalcly (IINIOII), Rcuul~wcork smnlltilmns WI sunplu walInM aqrunwnls for rrnll- Uplication ralcs suggesl xorw Iowcr Iimm ruliihn~ wmprow hlmliahou numtwr ml rule, wmpfes~ion, and capmrlc radius, Ihat is, a criticality condition,

pr > 120grlcm2 , (11) for p the average density, and r the radius at cnticalily, as well as a disassembly conslrainl,

ra> 30cm/psec , (12) with a rbe peak multiplication rate. The greater the nurntwrs of initiating antiprolons, and lhc shoflcr the injection pulse length, Ihe higher will be the multiplication ralc. The higher tlw compressibility and USCIasger IIN! capsule radius, the higher will also be the reaction rate. The experiments plannrxl a: SHIVA STAR will provide impormt and requisite dala points 10 benchmark cal- In initial capsule (homogeneous UDT ) simulations using reactor ~~e~~ a~ ~els in such applications. ., fmrly compressed slates ( 150 g /cm 3, were necessary Ior ignition-hum, To gcl 10 final dcnsilies ~~thc 150 g/cm 3 range, drive pressures in lhc 200 Mb range also appear rcquisilc, using simple equalicrns-ol-sidle. Some- where near 10” initiating antiprolons arc needed for dcnsilics M 150 gm /cm 3, Icss al higher densitities, more al lower densities.

Trap Icchnology poris 10 many sysiems and experiments, and the mechanisms of anliproion annihilation pm- scss iclcrcsling fciilums not seen before, Los Alamos National Laboratory has been invcsligaling applications of amiprotons, has performed rclalcd and scoping anliproton calculations, and hopes 10 perform some anlipromn expirrwnls, following proof of happing technology ( I or’) potiatdu arsliprolons).

ttEFERENCkX

(1) A. Angelopoulos, A, Aposlolakis, T,A. Amwong, B. Bassallcck, G. Buechc. M. Fcro, M. Gee!, N. Graf, H. KCXM R.A, ISVIS, M, Mandclkcm. P. Fapm!lis, H. Polh, H, Rozaki, L. Sakclliou, J, Schultr, J Schwcrlcl, G. A. Srnhh, G.A. Smith, T, Usher, and D. N!. Wrslfc, Phvs. l.eII. B 205, 5%)( 191M). (2) R,Fi, %unon, Cross Sections For ~ Muted /ission, Radiation Transpofi Group Menurriindum, X-6:RES- 91-331 (1991). (3) I.E. Morel, Nut. Sri. k%g, 79, 340( IW I ), (4) B.R. Wicnkc and J,E. Morel, Nut. /nrm, M~/h. I’hys. Res, A 2450, 162( 19N5).

(5) R.A, Ixwis, R, NcwIon. G.A. Smith, W.S. Tonthuckcr,iiiyJ R.J, Kwwlcltcr, ,4n Amipromn C’uIG/vsI l’or Inerliul (’on,pnemtn: I’usion Propulsion, AIAWSAfilASiSiE/ASEE JoIm Propulsion Conlumc(! Rcporr, AAIA 90-2760, OTlmIdo ( 1990). (6) D.G, Matlltind and J,R. Nix, Nut, S(I, 1,’ng. !W, 345 ( 19H2). (7) J, Ligou, Nut. Sci. F.’ng, 63,31 ( 1977), (8) R,K Cole ml J.H. Rcnkcn, Nut. Sri. En,q, M, 345 ( 1975). (9) T,A, Mchlhom and J.J, Dudustiidl, J. (.omp. Phvs, 311,M ( 19!0, ( 10) r.R, Hill and W. H. RutMJ,T/MIA’: A rime -/)cpmdtn/ I;\/?lici/ /)iscrrlt ordinol?s Pro,rr(Jm I’or The Sohmon of Muhigroup Trunspcr/ }@.wiwts, Los Abnos Scicnllllc l,ahmlo~ Rcpotl. LA-620 I -MS, Los Alarnm ( 1976). ( 1I ) R.A. Im’is, R. Ncwlon, G.A, Smith. and R.J. Kaswlcilcr, NIK. Ski. lhh’ 109,41 I ( 1991). (12 ) Y B. fildo”ich ml Y.P. Raiser, Phwcs (?/’ Shock WCILVS And Hi#h Ttmpwwt Hvdro@numic Plwmmcnu, Acmh!mic F+css, Nut Yoprk ( 1966),