Robert A. Hqrdekopf, Deputy Division Leader E&vardA. tteighway, Deputy Division Leader .*.',-.• •-•.,..•,... ^!,.v _.. _• ._ ,- •_.-
51'
nds far -. jhalt LaserInitiative^i^ELf)...... r Collider.
' Physics and Special Prpjwts......
' JS 1 -ft-"
1 j ,/
3'"^^^^*n^^^^fl5^5^^J^^?I^^^^^^^^^^^^^' ^
— ••{
/1
Stan Schiiber, AT Division Leader Foreword
Accelerator Technology Division ix hoiewoitl
SSCL 4.8%
AFEL/POP 7.1%
APT/ATW2.10/ HPMW3.1%
FEL 3.9%
NPB(Other) 6.3%
The division tenceiaan nous, was office; we are ES&H training. manager workload. Tltes© time in pmgrammatfc worn
Acieteiali/i linisum Foreword
Accelerator TiLlmalati\ DIUSIOII xi Programs and The Ground Test Acceltmtor Program ; 2 Defense Free-Electron Lasers 6 Program Development AXY Programs .; 12 A Next Generation High-Power Neutron-Scattering Facility (LANSCEII) 7.7..: ;..... 14 JAERI OMEGA Project and Intense Neutron Sources for . .. Materials Testing 16 Advanced Free-Electron Laser Initiative (AFELI) 17 Superconducting Super Collider 19 The High-Power Microwave (HPM) Program 20 Neutral Particle Beam (NPB) Power Systems Highlights 21 Industrial Partnering. 22 Programs and Program Development • The Ground Test Accelerator (GTAi Program
- 300 hours of operation. The reduced H, gas How lessens the need for pumping and thereby allows for a reduction in the length of the LEBT. Off-line tests of the 4X upgrade source "
Act clamor Technology Division Programs and Program Development • The Ground Test Accelerator (GTA) Program
The IMS was thoroughly evaluated power cryo lest bed. All 10 DTL ments made on the following: during experiment 1C. We measured modules will undergo the same test centroid steering, transverse and sequence before installation on the RFQ matching and steering longitudinal emittance. phase scans, beamline. A picture of 8 DTL modules RFQ, IMS. and DTL transmission and transmission. When we modeled in various stages of completion is DTL transverse emittance versus the beam transport for low-brightness shown in Fig. 1.1. • macropul.ie time currents, we discovered the fixed- • IMS variable field quadrupole times focusing strength of the quadrupole The first module was installed on the • IMS bwicher times steering magnets had to be reduced. beamline in vacuum vessel #1 (the • DTL times This reduction will result in a more entire 24-MeV DTL will be housed in DTL longitudinal emittance vs input "robust" behavior of the IMS. We plan two vacuum vessels). It was fully energy to grind the aperture of the steering integrated with diagnostics and controls Beam centroUL vs steering (DTL, IMS) magnets to reduce the field strength. and reconditioned in situ. Phase scans vs power f DTL, IMS) RF phase and amplitude control Drift Tube Linac (DTL) During experiment 2A, the first module verification was commissioned with the ion source, Beam jitter The two main thrusts in the DTL area RFQ, and IMS, resulting in the most X-ray calibration of DTL power included installing and commissioning complete and successful GTA commis- Slit and collector vs microstrip probe the first DTL module on the beamline sioning run thus far. The run demon- steering measurements (experiment 2A) and fabricating, strated integrated operation of all Hybrid LINDA tests assembling, and off-line testing elements of the 24-MeV accelerator. Video profile tests modules 2-10. The purpose of experiment 2A was to characterize the beam and the operation Radio Frequency (rf) Power The first module was fully assembled; of the structures, to verify the design, drift tubes were aligned at room and to prepare for beam transmission During the DTL commissioning run temperature, and the module was tuned and acceleration through all 10 DTL (experiment 2A), all elements of the rf at room temperature. This included modules. power system were operated for the tuning the cavity to 850 MHz and first time in an integrated mode. Three adjusting the couplers to achieve The operation of the 3.2-MeV accelera- tetrode amplifiers provided reliable desired axial field distribution. We tor (Fig. 1.2) was very reliable; all 425-MHz power to the RFQ (135 kW), checked room temperature alignment structures performed well. Recondi- to the first IMS cavity (.6 kW), and to and tune at the cryogenic operating tioning of the DTL module was rapid: the second IMS cavity (12 kW). One temperature of 20 K in the low-power 0.5 min without breaking the vacuum 850-MHz dual-klystron modulator cryo test bed; DTL positioners were during operation, 10 min without provided power for the first DTL also exercised, and the position change breaking the vacuum overnight, and 1 module (60 kW) and the high-power of the DTL from room to cryo tempera- hour after opening to air. The source conditioning stand. The system was ture was measured. Next, the module delivered a very quiet, reliable beam. very responsive to the daily needs of was conditioned up to 130% of the Vast amounts of data were compiled as the commissioning team and worked operating power at 20 K in the high- a result of the wide variety of measure- reliably.
Fig. 1.1. Drift tube linac module satlis (Juanila Romero. AT-4). Production line in full operation; five modules complete.
Accelerator Technology Division 3 uiul Hrnfinwi Dt'vcloptiienl ' Ihf Lirmnul lf\t \ttfl
during ihe last commissioning run (experiment 2Ai and enabled the commissioners to collect, archive, and r-".:ic\c daia quickly and reliably. Several diagnostic processes such as emittauce scanning and phase scanning have been automated. They, work well and have reduced dramatically the lime required for daia acquisition.
i Recently during experiment 2A we introduced several new cop!1' .1 lunc- tioiis and demonstrated then: success- fully. These include ihe fasl-prolecl function, ihe alarm manager, and an adaptive feed-forward module thai controls phase and amplitude fluctua- tions of ihe rlcav its power. The j control room was made lulls opera- ; lional and is working satisfactorily.
Cryogenic Cooling Plant Fig. I.-. The 3.2-Mc\'accett'ruttir is ht'inti ft iniwnniftl in rlw (if A tunnel I It'll. Durrvl Samltnal and Ralph (iarfia, AT- I A 40-kW liquid hydrogen plant was The off-line testing of the 12 Thomp- assemblies and th.ee Taradas cups on I designed and built during the last .1 son klystrons was completed success- the diagnostics plate complete the beam i sears. This plant uses liquid hydrogen lulls. The second modulator has been diagnostics tor the 3.2-MeV accelerator. I as ihe primary coolant fora high- ; assembled and checked out on the pressure gaseous helium loop that mezzanine. The remaining modulators The beam diagnostics worked well actually cools ihe accelerator eav ilies lo are in various stages ol assembly (Tig. during experiment 2A. although : 20 K. One of (he most difficult and I.}i. The large capacitor hank used for i|uesiions remain regarding ceniroid lime consuming lasks involved creating the 2-ms pulse has been position and angle measurements ol die i preparing ihe Safely Analysis Report assembled anil is reads lor integration large aperture microstrip probes used on • and receiving final approval from the with the crossbar system and the 5-A the diagnoslics plate. Redesign ol the health and safety organizations of the high-w>lkige power supply. The low • beam tube for heller conhnuily and Laboratory and Department of Knergv. level rl control system has been symmetry of the return currents should which look .1 years and several man- designed, and circuit hoard production correct this defii ncv. years ofeffori to accomplish. More- for the prototype has begun. I over, ihe cryogenic plant passeil ils We developed and used successfully a ] acceptance lest in May and is now fully Beam Diagnostics lasi-proiect module based on the operational. The 40-kW planl will he transmission loss through the Ri Q and used lo cool ihe entire 24-MeV UU All beam diagnostics necessary lor DTK. which is measured as a current i accelerator in TV I 4.
diagnosing and controlling the beam dillerence. We also developed and 1 have been integrated into the accelera- performed off-line tests on a prototype ; We continue lo employ ihe existing tor and thoroughly exercised These beam loss monitor based on y-ras : 700-W Koch refrigerator lor all include an automated emillance scanner detection. Ihcse beam-loss monitors ' experiments wnh the existing heamline used !o measure beam emiiianee in the vwll be used ihroughoul the accelerator up lo V2 MeY and lor ihe high power KKMT Toronls. he!ore and alter ihe al higher energies. conditioning of all DTK modules. RTO and ihe DTK. are used to measure beam currenl and transmission. Controls Optics Microsmp probes localed in ihe IMS anil on the diagnostic plale measure "The controls sy stems (i.e.. sssiem I he (r I A optics team continued lo beam cenlroid position, angle, ami sofissare. application sollware. and the support the neutral particle beam space energy \ video protik- sssiem aller KK'si have kept pace with the demands experiment iM'BST. 1 design effort led the IMS measures centroiil prolile and ol ihe growing Cil A facility. These by (irutnnian. Several designs were positinn. Two sin and collector systems exhibiteil good reliabihlv produced.
At < rlrrulur I ft hntili>n\ Dnisinn Programs and Program Development • The Ground Test Accelerator (GTA) Program
The design for the ground based optics permanent magnet. The bend is de- Summary for GTA progressed successfully and signed to transmit currents up to 50 mA. culminated in a physics design for the FY i992 was very exciting technically. high-energy beam transport (HEBT) A major breakthrough was achieved It culminated with the 3.2-MeV section the 180J bend, and a conceptual during FY 1992. We developed a commissioning run that demonstrated physics design for the telescope. The method to contour high-order field the integrated operation of all elements key parameters for the optics design are components to minimize the feed-up of of the 24-MeV accelerator. The • 3.1-in diameter bend, geometric aberrations. The contoured accelerator ran successfully during 3 • //-m long. 12.5-cm diameter high-order components were built into weeks of experimentation, the beam telescope, the permanent-magnet objectives by current was quiet and stable, the if • 5th order aberration control, and tailoring the radial and rotational power system delivered power reliably, • 6 firad divergence. positions of the permanent-magnet and the cavities performed without stacks. Electromagnetic corrector electrical breakdowns. Our commis- The purpose of the HEBT is to match packages for second through sixth order sioning team will be busy for months the DTL to the bend and provide for correction permit the correction of evaluating the large amount of data longitudinal expansion and beam effects due to geometries, ambient fields, acquired. steering into the bend, which is and space charge. By using this method, accomplished with four variable field we can reduce the telescope length to Our plans for FY 1993 are to install all permanent-magnet quadrupoles while 11 m. To minimize the cost of the new 10 DTL modules into 2 large vacuum providing for a dejitter cavity if objectives, we will reuse the permanent vessels over the waveguide basement. necessary. magnets from the original 40-m tele- In parallel with this activity, we will scope objectives. complete the 5 dual-klystron modula- The bend's purpose is to demonstrate tors and build 1 preproduction low- the feasibility of 180° bending of high- level rf control system. Because of current beams with minimal emittance severe funding constraints, we will growth and beam loss. The bend bring the optics designs only to the accomplishes this with a triple achro- preliminary design review level without mat, each containing five cells with a making any long-lead procurements. defocusing, bending, and focusing
Fig. 1.3. Bill North (left). John Bancroft. Bill Reass. and Glen Zimmerman prepare five high-power klystron modulators for operation.
Accelerator Technology Division Programs and Progrum Development ' Defense free-Electron Lasers
In addition to supporting the APLE program, the APEX facility was used to support a DOE-funded experiment that demonstrated the photolithography of semiconductor computer chips using a FEL beam. Al the Boeing facility in Seattle, the joint Boeing/Los Alamos high-duty 5-MeV-photoinjector test Introduction tion. Highlights included lasing at a stand achieved operation at 25% duty wavelength of 837 nm. the shortest to factor and an average electron-beam power of lo() kW. Such high-duty During 1992 the Los Alamos Defense date for a Los Alamos FEL. Ultrahigh operation of a photoinjector was an Free-Electron Laser (FEL) Program current densities of 7000 A/cm-' were important milestone on the road to the continued 10 be teamed with Boeing demonstrated from the APEX photo- high-power FEL goal. Aerospace and Electronics in support ca'hode. significantly exceeding the of the Average Power Laser Experi- previously reported values for ment (APLE). The ultimate aim of the multialkaii photocathodes. The electron The APLE program involves many Los APLE program 's to demonstrate that a beam's brightness at the end of the Alamos National Laboratory groups: FEL can produce laser light with an APEX 40-MeV accelerator was APLE Project Office (program man- 1 : average power of 100 k\V. A major Los measured to be 3 x K) - A/(m-rad) at a agement), AT-7 (accelerator physics Alamos contribution to this effort is the current of 135 A. making the APEX and APEX project leadership), CLS-6 APLE Prototype Experiment (APEX). beam one of the world's brightest high- (drive-laser and optical diagnostics), The purpose of APEX is to demonstrate current electron beams. Single-bunch P-15 (electron beam diagnostics), the basic physics and technology of wakefield effects were measured MST-7 (photocathodes), X-l (theory APL E at low-duty factor. Following the directly for the first time using fast and simulation), AT-4 (mechanical engineering), AT-5 (rf controls), and 1991 commissioning of APEX, the streak camera techniques, and a scheme AT-8 (automation). 1992 effort focused on physics experi- for mitigating wakefield effects in a ments associated with the FEL opera- high-current accelerator was developed.
Fin. 1-4. APEX heamline in September 1992. showing the oscillator wiggler region (Patrick Schafstall. AT-7).
Accelerator Technology Division Programs and Program Development • Defense Free-Electron Lasers
Background untapered permanent-magnet wiggler photoinjector. approximately 80 cm in the Halbach configuration. from the photocathode surface. Funding for the Los Alamos Defense FEL Program is provided by the Detailed descriptions of the APEX The electron current at the cathode Strategic Defense Initiative Organiza- accelerator and FEL can be found in surface is not measured directly. tion (SDIO) and the United States Refs. 2-5. Figure 1.4 shows the Because the electron emission from the Army Strategic Defense Command oscillator wiggler and adjacent cathode is prompt, the temporal length (USASDC). Under the auspices of sections of beamline. of the electron pulse near the cathode is SDIO, a collaboration on FEL research less than or equal to the drive-laser was initiated between Los Alamos and Photoelectron Emission pulse length. We measured the charge the French Atomic Energy Commission The photocathode material used at for each micropulse reaching the wall- FEL facility at Bruyere-le-Chatel near APEX is CsK,Sb driven by a current monitor. The current at the Paris. The French are in the process of frequency doubled Nd:YLF laser.'1 cathode is estimated by dividing the commissioning a FEL driven by a We chose this configuration because total charge per micropulse by the radio-frequency (rf) photoinjector linac it produces high electron-beam width of the drive-laser's FWHM similar to that at APEX. During FY current for modest drive-laser power. pulse. 1992, a number of mutually beneficial We studied the photoemission exchange visits were made to both FEL current as a function of both drive- The variation of drive-laser phase and facilities. laser power density on the cathode power have their analogs in thermionic and injection phase relative to the rf. cathodes. Phase is analogous to the Following the initial lasing of the Figure 1.5 shows the photoemission cathode voltage, and power is analo- APEX FEL in June 1991, we directed characteristic curves for our cathode. gous to cathode temperature. (Note our efforts in FY 1992 toward charac- In generating these curves, we held that increasing the drive-laser power terizing the electron and optical beams the cathode's diameter at a constant does not increase the emission energy with tiie goal of verifying the design 3 mm and the drive-laser pulse of an electron; it increases only the codes used for the APLE FEL design. length at 10 ps. For each drive-laser number of electrons emitted.) Figure A secondary goal was to complete the power, we varied the injection phase 1.5 illustrates the source-limited regime APEX beamline through the 150- and measured the charge extracted (low drive-laser power) and the space- degree bend and FEL amplifier leg. A using a wall-current monitor charge-limited regime (high drive-laser new effort was undertaken to bring the immediately downstream from the power). At low drive-laser power, the sections of the APEX beamline under automated computer control. These Space charge limited goals were achieved as planned. regime 5 nC, 290 A, 68 nC/cms peak Achievements 6000 i - - - sin (if)'5 fit to data During FY 1992, the APEX linear T3 o accelerator operated in a hitherto unexplored regime of high current and high charge (>100 A at 1 nC) and low emittance (< 5 Jt mm-mrad normal- i 4ooo >. £ ized, rms).' The 40-MeV linac has four 0) Q. separately driven tanks: the First is a 6 D E MeV cn-axis coupled structure, and the remaining three are side coupled. All S o 2000 the structures operate in the nil mode Normal source limited at 1.3 GHz. The peak current is e 0.4 nC, 35 A, approximately 300 A in 15-ps full- 5 nC/cm2 peak 111 width-at-half-maximum (FWHM) bunches. Individual bunches are separated by 46 ns. This bunch spacing Osin NJ! •*••- 90 180 is determined by the round trip time for Drive Laser Injection Phase (deg.) the optical pulst in the FEL resonator. The FEL configuration used for our Fig. 1.5. Phoioemission current density at the cathode vs drive-laser injection phase relative experiments was an oscillator with a to if in the space-charge-limited regime (drive-laser power density = IS MW/ciir). aril the near-concentric resonator and an source limited regime (drive-laser power density = 1.3 MW/cnr). the cathode radius was 1.5 mm and the drive-laser pulse width was 10-ps FWHM.
Accelerator Technology Division Programs ami Program Development • Defense Free-Electron Lasers
curve makes the transition from spaee- over440 micropulses. The predicted Transverse Wakefields charge-limited emission (0" to 20") to curve is generated using the code We have paid particulai attention to the source-limited emission (flat top) PARMELA. the primary beam- mechanisms that degrade the emiUance and then back to space-charge limited dynamics code used for electron-linac and brightness of the electron beam. again. This corresponds to the normal design at Los Alamos. During FY \W->2. we focused on Ihu operating drive-laser power and current effects of transverse wakefields in the density at APEX. The uimtimnilizt'd emittance at 135 A linac. Because of dipole rl fields in the is 0.046 K mm-mrad, which is suffi- side-coupled accelerator tanks, trans- At high drive-laser power (IS MVV/enr cient for FEL lasing at wavelengths as verse kicks are experienced in the or 18 uJ/cnr per mieropulse), the short as 160 run. The measurement of electron beam that induce head-to-lail emission is always in the space-charge- such low emittances at high charge and transverse-wakefield kicks in the limited regime. In fact, we have current from a photoinjector linac micropulsj and hence result in emitlance observed current densities as high as verifies the solenoidal emittance growth. The trajectory required to 6800 A/cnr. The corresponding charge compensation scheme proposed by minimize the wakefields is not intu- emitted per micropulse is 68 nC/cnr. Carlsten.- itively obvious to the accelerator For a nominal cathode diameter of 10 operator. To assist in determining the mm, an extracted charge of 50 nC per Figure 1.4 shows the corresponding optimum trajectory, we installed our micropulse would be expected for the normalized rms brightness as a function streak camera to monitor the electron equivalent drive-laser power density. of current. The brightness is defined as micropulse temporal and spatial profile This regime is far from our normal on a screen located at the end of tank D. operation. Because our accelerator is B = 21/^ . Consequently, we were able to directly not designed to effectively transport observe the effects of the wakefields on such high charges and currents, we where I is the micropulse current and e the electron beam as shown in Fig. 1.7. anticipate that significant emittance is the rms cmittance. The factor of TC in The operator can easily choose a growth will occur. However, thvse the definition of emittance is explicitly trajectory that minimizes ihe wakefields results demonstrate the capability of used to determine the brightness. The and optimizes the emittance. A detailed photocathode systems to produce very maximum brightness observed to date knowledge of the opiimum trajectory is high currents. is 3 \ 10" AAm-rad)2. at a current of not required. The degree of emittance 135 A and an electron-beam energy of degradation resulting from wakefields is Emittance and Brightness 36 MeV. The energy spread, whicii shown in Fig. 1.6. In this figure, the PARMELA curve without wakefields Following the photoinjector. the beam was averaged over 220 micropulses. corresponds to the emittance when the is accelerated to approximately 40 was measured at 0.24'/f FWHM. This K electron beam is steered to minimize MeV by three side-coupled /2- measurement compares with a wakefield effects. The PARMELA curve standing wave structures referred to as PARMELA prediction of 0.15'* for a with wakefields corresponds to the tanks B. C. and D. Each tank is single micropulse. electron beam when it is steered to separately powered by a Thomson center on the screens between each TH2095 klystron. Between each tank accelerator tank. we have insertable view screens from which the electron-beam profiles are imaged using optical-transition radiation (OTR). Electron-beam micropulse current is determined from PARMELA: 20 with wakefields wall-current-charge monitors and OTR streak-camera micropul.se measure- ments. 15 DATA Emittance, rms (K mm-mrad) Emittarje is measured at the end of the 10 linac using the quadrupole-sean technique. The emittance numbers PARMELA: quoted here are normalized root-mean- without wakefields square values. Figure 1.6 shows the emittunce as a function of micropulse 1 nC 5nC current measured at an electron-beam 100 200 300 400 energy of 36 .VIeV. The numbers Micropulse Current (A) plotted are the geometric mean ol two orthogonal measurements averaged /•Vi;. I.ft. Electron hewn rms normalized emillance v * mil ro/nihe current.
Accelerator Technology Division Programs and Program Development * Defense Free-Electron Lasers
FEL Performance 0 • o = APEX Data The detailed specifications of the 3.0 •-o... APEX FEL resonator and wigglers are o given in Ret". 5. Typically, lasing has ••---p. been at wavelengths near 3 j.im. The 1.0 "o- 6.9-m resonator is an asymmetric, near- '6 concentnc design. The asymmetry Normalized 03 results from placing the optical waist at Brightness (10t2A/(m-rad): the vviggler center, which is 0.5 m 0.1 upstream from the resonator's geomet- Old Los Alamos linac ric center. The resonator mirrors are with thermionic gun coated with a multilayer dielectric to 0.03 reflect greater than 99% at 3.0 urn. A 1 nC , 5nC small traction of light, which is 100 200 300 400 transmitted through the optic, is Micropulse Current (A) transported to a diagnostic table located within 5 m of the out-coupler. Sensors Fig. 1.7. Electron beam rms normalized brightness at 36 MeV vs micropulse current. The on this table allow for characterization estimated brightness from our previous accelerator with thermionic injector and 20-MeV of the small-signal gain, cavity loss, energy is shown for comparison. energy, spectral content, spatial intensity distribution, and temporal intensity evolution. tion and operating parameters have at the start of the macropulse can make been performed using the FELEX the initial lasing unstable. The resonator mirrors {end to suffer code." This small-signal gain predicted coaling damage when the macropulse- by FELEX is approximately 200%. Our average intracavity mirror flux is high. experimental measurements show gains Consequently, the macropulses are kept in excess of 160%. The start up of the short (20-40 us), and the charge is kept optical macropulse is shown in Fig. 1.8. low (1 nC). During the lasing described We have found the small-signal gain below, the electron-beam micropulse is measurements difficult to perform. usually 10-ps FWHM, with a FELEX simulations show that the gain macropulse energy spread of less than is large for only a small number of 0.5% and a normalized rms emittance micropulses (approximately 10 of approximately 4 K mm-mrad. micropulses or 0.5 us) at the start of the Simulations with the above confisura- macropul.se. Furthermore, rf transients
(a)
Fig. I.H. Direct observation of transverse wakefield kicks an electron micropulses (a) head-to-tail kick removed by optimum choice of steering. Accelerator Technology Division Programs and Program Development • Defense Free-Electron Lasers When the FEL is lasing at wavelengths step mirror as a replacement for one of Physics and Industrial Control System near 3 um, very strong sidebands are our regular resonator mirrors.'"" We (EPICS) control architecture developed evident (Fig. 1.9). Such strong side- believe the phase-step mirror technique for the Ground Test Accelerator as part bands would reduce the efficiency of a will be more applicable to high-average of the Neutral Particle Beam program. high-extraction FEL with a tapered power FEL applications than the By the end of FY 1992, we had wiggler. Recently, we directed our Brewsier plate technique. converted all the beamline magnets to efforts toward the study of sideband computer control. An automated suppression techniques. The first Short-Wavelength Lasing method of measuring the electron-beam suppression technique we attempted was During FY 1992, approximately 25% emittance was implemented using the the introduction of Brewster plates into of APEX effort was devoted to a DOE- quadrupole-scan technique. Automa- the resonator cavity.5 We found that funded program to develop ultraviolet tion of the drive-laser was considered these plates strongly suppress the FELs for photolithography of semicon- to be one of the more intractable sidebands. The suppression occurs at all ductor computer chips. The goal of the problems. A major breakthrough was a plate angles including Brewster's angle. proof-of-principle experimtMit at method developed to determine the At Brewster's angle the insertion loss of APEX"'- was to show the modestly phase of the drive-laser mierooulses the plates is approximately 0.5% per sized FEL could be used to produce relative to the rf phase of the accelera- pass. We believe that the suppression ultraviolet light (250 nm). As part of tor. Using this mc'.hod. we were able to occurs because the Brewster plates act this effort, we have begun harmonic implement automated feed-forward as a dispersive element. The first lasing with both our existing perma- control on the drive-laser phase that sideband is displaced by approximately nent-magnet wigglers and a new gave long-term stability of less than 2 y/c in wavelength from the fundamen- electromagnet microvviggler. By the ps. In addition, the drive-laser tal. Dispersion in the plates results in a end ol'FY 1992, we had lased at micropulse temporal width was also round trip path-length change of 17 um wavelengths down to 827 nm with a brought under automatic control. The relative to the fundamental. Previously permanent-magnet wiggler. Using the pulse width is now controlled at 10 ps we showed that detuning a cavity microwiggler, we observed spontane- with a jitter of less than 0.5 ps. These without Brewster plates by approxi- ous light emi.^uii at wavelengths close techniques eliminated many of the mately 10 um was sufficient to suppress to 500 nm. manual adjustments previously sidebands. However, detuning the cavity required to maintain the drive-laser in also results in a reduction in the gain on Automation stable operation. Control of the electron the fundamental. The Brewster plates The APEX control room was originally current from the photoinjeclor was allow the detuning of the cavity for the designed and constructed in the early automated by developing a feed- sidebands while maintaining cavity 1980s. All controls were manur., with forward loop between a current monitor synchronism on the fundamental. no computer intervention. In 1992 we and a drive-laser power attenuator. received funds from USASDC for the We have begun collaborating with purpose of developing computer Future Plans Mission Research Corporation to test a controls and automation for subsystems new method of sideband suppression. of APEX. As a bash, for our control Continued contraction of the national This technique involves using a phase- system, we chose the Experimental t'efense FEL program resulted in a funding reduction for the Los Alamos program. In July of 1992, a partial termination nciice was received from USASDC, which will result in the elimination of the APEX experimental program and the FEL theory effort in FY 1993. The remaining Los Alamos effort in defense FELs will be in direct APLE support in the areas of photo- cathode drive-lasers, electron beam diagnostics, and low-level if controls. APEX will continue lo operate for part of FY 1993. The main effort will be lo support the photolithography program by pushing the lasing wavelength to smaller values with the ultimate goal of 250 nm. Fig. 1.9. Start up of losing at 3 fjm, showing a small-signal gain of 160% per pass. The individual micropulses are 46 us apart. 10 Accelerator Technology Division Programs ami Program Development • Defense Free-Electron Lasers References 1. B. E. Carlsten, J. C. Goldstein, E. J. Pitcher, and M. J. Schmitt, "Simulations of APEX Accelerator Performance in the New Non-Thermalized Photoinjector Regime." (to be published in Mid. Instnt. & Methods). 2. B. E. Carlsten, L. M. Young, M. E. Jones, L. E. Thode, A. H. Lumpkin, D. W. Feldman, R. B. Feldman, B. Blind, M. J. Browman, and P. G. O'Shea, "'Design and Analysis of Experimental Performance of the Los Alamos HIBAF Facility Accel- erator using the INEX Computer Model," IEEE J. Quantum Electron. 27, 2580 (1991). 3. P. G. O'Shea, "The Los Alamos High-Brightness Photoinjector," in High- Brightness Beams for Advanced Accelerator Applications, (College Park, MD, June 6-7. 1991), AIP Conference no. 253, p. 182. 4. P. G. O'Shea. S. C. Bender. D. A. Byrd. B. E. Carlsten, J. W. Early, D .W. Feldman. R. B. Feldman, W. J. D. Johnson, A. H. Lumpkin, M. J. Schmitt, R. W. Springer, W. E. Stein, and T. J. Zaugg, "Initial Results from the Los Alamos Photoinjector-driven Free-Electron Laser," NucL Instru. & Methods A318, 52 (1992). 5. P. G. O'Shea, S. C. Bender, B. E. Carlsten, J. W. Early, D. W. Feldman, R. B. Feldman. J. C. Goldstein. K. F. McKenna, R. Martineau, E. J. Pitcher, M. J. Schmitt, W. E. Stein, M D. Wilke, and T. J. Zaugg, "Performance of the APEX FEL at Los Alamos National Laboratory," (to be published in NucL Instru. & Methods). 6. J. W. Early, J. Barton, R. Wenzel, D. Remelius, and G. Busch, "The Los Alamos FEL Photoinjector Drive Laser," IEEEJ. Quantum Electron. 27, 2645 (1991). 7. B. E. Carlsten. J. C. Goldstein, P. G. O'Shea. and E. J. Pitcher. "Measuring Emittance on Non-Thermalized Electron Beams from Photoinjectors," (to be published in Nucl. Instru. & Methods). 8. B. D. McVey, "Three-dimensional simulations of FEL Physics," Nucl. Instru. & Methods A250,449 (1986). 9. J. E. Sollid. D. W. Feldman and R. W. Warren, '"Sideband Supression for FELs," NucL Instru. & Methods A285. 153 (1989). 10. A. H. Paxton and M. J. Schmitt. "Sideband instability in FELs - a new tech- nique for supression," IEEEJ. of Quantum Electron. 26, 1167 (1990). 11. B. E. Newman. R. W. Warren, J. C. Goldstein. B. E. Carlsten, M. J. Schmitt, S. C. Bender, D. W. Feldman. and P. G. O'Shea. "The Los Alamos POP Project: Design of FEL Experiments in the Ultraviolet and Beyond," NucL Instru. & Methods A318. 197(1992). 12. R. W. Warren. P. G. O'Shea, S. C. Bender. B. E. Carlsten, el al.. "Lasing in the Ultra-Violet with a Microwiggler." (to be published in Nucl. Instru. & Methods). Accelerator Technology Division II ami /' '" /VIWIJ/I/HC/I/ • l.\T /Vn With the closure of ihe Nl' office of 1X)H al the end ni IW2. the APT pro- gram is in he lransfcrred lo the Defense Programs (DP) office. Accelerator Design 1992 Status Report for AXY s'udv of ihe concept. The study was The APT linac reference design calls fora 1-CreV, 200-niA cw proton linac. Programs structured as a collaboration between Los Alamos Nalional Laboratory The high-energy-beam transport serves one of two alternate production target/ Potential applications c high-power (LANL). Brookhaven Nalional Labora- blanket assemblies, with a specification aeecieraior-driven spallalion neuiron tory (BNL). S.india Nalional Labora- ol'75'f overall plant availability The sources expanded dramatically during tory (SNL), and was initially managed linac architecture pictured in Fig. 1.10 |W2. the Department of Energy by the New Production (NP) office of consists of a funneled front end that iDOlii funded an IS-monih design DOE. NP's purpose is lo provide APT combines 100-iuA beams from two 20- siud> of Aceeleriiior Produciion of input to the Programmatic Environmen- MeV 350-MH/ linacs, followed by two Iriiium i APT i. ihe Nalional Academy tal Impact Statement (PEIS) lor Com- 700-MH/ high-energy accelerating of Sciences re\ iewed Accelerator plex 21 and to assess ihe technical structures lhal provide a 1-deV. 200- Transmutation of Waste (ATW'I. and a feasibility and costs ol the APT con- mA output. Each of ihe low energy I aboraiory-Industry collaborajion put cept. LANL is responsible for the APT linacs consists of a 75-keV proton forward a proposal lo studs Accelerator acceleralor design and lor a target/ injector, a 3-MeV radiofrequency qua- Based Conversion (ABC) of Russian blanket and processing system based on drupole (RFQ). and a conventional weapons plutonium. A I..os Alamos convening the irilium decay product drift-lube linac (DTL). The accelerat- proposal was also submitted lo the "He back into tritium. BNL is respon- ing structure following the funnel is a Defense Nuclear Agency (DNA) for sible for a target/blanket system similar short-tank bridge-coupled drill tube huilding the lust stage of a high-power to the one presented to the Energy linac (BCDTL) lhal contains no qua- coniiiuious-\v.i\c lew ) proton linac Research Advisory Board (ERAB) in C drupole magnets in the drill lubes. The from end 10 demonstrale key aspects of I JS9. based on a matrix of lead and final accelerating structure, which is Ihe technology The steadily increasing LiAl rods. SNL is responsible tor the about S50-ni long, is a coupled-cavity nuinber af programs are now referred env ironmental, safety, and health linac (CCL) in which each 14-cell tank in colleciiveh as AXY. where ihe A evaluation of the APT design and spe- is driven by a single high-power klys- Mauds lor high-power acceleralor. and cifically for coordinating the PEIS tron. A kev feature of ihe high-energy ihe remaining letters represent the input. The APT study is lleshed out by structures is a large aperlure-lo-beam- specilic application. contracts with industry for engineering support, costing, and A/E services to si/e ratio in order lo meei ihe very low define the Balance ^[ Plant (BOP). beam loss requirements needed for Considerable progress was made in developing acceleralor conceptual designs, in identity ing and addressing Furnel key technical issues lor high-power cw BCDTL Coupled Cavity Linac (CCL) IIJKICV and in examining important (700 MHz) (700 MHz. 200 mAl design questions, such as mechanisms Injectors t loi ihe generation ol beam halos. A I- I M-Cell Tanks weck workshop on high-power accel- Doublet Focusing 20 MeV 100 MeV 1000MeV erators ami spallalion targets was held 3 0 MeV Emittance Filter in Siivenihei Ixiuivn I us Alamos 75keV designers .mil Lolleamies from ITkP 30 m — I — 110m- I 860 in and \IK II in Museovv ami Iroin other uisiiiuies in Kussi.i. Beam power 200 MW Total RF power 275 MW APT Program RF to beam efficiency 0.73 AC to RF efficiency 0.58 AC power requirement 500 MW I'ollow ing ihe SIILLCSSIIII ouleume ol a Average CCL gradient 1.25 MV/m JASON panel review ol I us Alamos Transverse output emittance 0.04 ;i cm-mrad and Mroiikhaven proposals lor Accel- CCL aperture/beam-size ratio 13-26 eralur PruduclKUi ol 1 nlium in January ihe I)()!-. decided lo kind an IS-inonlh I IV 1.1II. \l'l i: \< i-rlrriiliir Ici linnlni;\ Division Proi;mins and Proxmm Development' AXY Programs ensuring hands-on maintenance. Short mal-llux neutron sources surrounded by that would develop a reference design tanks and a quadrupole doublet focus- D,O blankets in which the materials to for an Accelerator Based Conversion ing scheme help in the attainment of be transmuted flow in aqueous-bused (ABC) system thai would be built in this objective. Alow accelerating carrier loops. This system could trans- Russia as a joint US/Russian technical gradient (1.25 MV/'ni. average) in the mute the aetinide and fission product project. The study would also assess CCL prov ides high rf efficient'} and u aste of about eight 1 -GWe light water the feasibility of implementing an Inte- minimizes life-cycle costs. reactors, converting it to stable or grated Test Facility (ITF) for shorter-lived products that do not re- prototyping the ABC process at an A high-energy beam transport (HEBT) quire deep geologic storage. A more upgraded version of LAMPF. Several system conveys the protons from the advanced high-temperature ATW sys- interactions between LANL, US indus- end of the linac to one of two alternate tem, based on a helium-cooled graphite trial participants, and relevant Russian tritium production target/blanket as- blanket with molten salt carrier loops, scientific institutes and government semblies. While one of these assem- is also being examined. It promises agencies took place throughout the blies is in production, the other can be higher electrical efficiencies, and opens year, culminating in a Moscow work- serviced. The transport system consists up the possibility of accelerator driven shop on target design and chemistry for of a doublet focusing lattice matched to suberitical fission systems that could ATW/ABC systems and a Los Alamos that of the linac. followed by an achro- convert fertile material to fissile fuel, workshop on ATW/ABC accelerator matic bend, and terminating in an ex- burn the fuel to produce energy, and design. Both workshops were held in pander based on nonlinear optical ele- transmute all long-lived nuclear waste November 1992. ments. The expander com ens the generated in the process. small-M/.e "early Gaussian beam distri- DNA Proposal bution from 'he accelerator into a large DOE Environmental Restoration and area uniform density distribution at the Waste Management (EM) i'unds have Los Alamos also submitted a proposal target face. supported chemistry and material bal- for funding to the DNA for developing ance studies for ATW. while accelera- a high-power ew accelerator front end Program Events tor and target/blanket design have been that is generic to ATW, ABC, and APT supported by LANL-directed research applications and that also has applica- The APT program received a status and development (LDRD) dollars. Key tion to a future LAMPF front end re- review in September 1992 of the refer- activities this year have revolved placement. Accelerating structure ence design. Key PEIS input data, such around a comprehensive review of frequencies have been chosen to match as estimated radioactive air releases, separations technology and transmuta- those of LAMPF. Thus, if the initial are to be provided to Sandia by the end tion systems (STATS) for high-level program can be extended into a 4- to 5- of January 1993. A comprehensive nuclear waste. This review is being year program, it will be possible to rev iew ^t' the complete APT system conducted for the DOE by a special develop a complete demonstration of design, including PELS impacts, is panel of the National Academy of Sci- the front-end cw accelerator technology scheduled for early March 1943. A set ences. The ATW accelerator design for transmutation systems. The hard- of topical reports on the design of all was reviewed by the STATS panel ware would then be converted into the aspects of APT. wiih participation by transmutation stibpanel in April as part first stage of a LAMPF accelerator industrial partners, will constitute the of a complete review of the Los upgrade suitable both for driving a final FY 1993 program deliverable. Alamos ATW schemes. recently proposed advanced spallation neutron research facility (LANSCE II) ATW Program ABC Proposal as well as an ITF that could evaluate ATW technologies. The proposal to The Laboratory i> continuing to study In FY 1992 an industry-led consortium, DNA includes an assessment to deter- Accelerator Transmutation of Waste wiih Los Alamos as a major partner. mine what is necessary to upgrade the iATW). The initial application ol this i proposed to study a special ATW sys- LAMPF linac's power level for ATW scheme was Incused on destruction of tem dedicated to converting returned technology and to implement the new the accumulated high-level radioactive Russian weapons plutonium. The pro- technology in demonstration facilities. wastes at the DOE's defense produc- posal, led by Grumman Aerospace The proposal also includes a study of tion siies. principally at Hanford. hut Corporation (GAC). is aimed at funds the intense pulse provided by the Pro- this year the study emphasis has shifted made available by the 1992 Nunn- ton Storage Ring (PSR) for weapons to include transmutation of spent com- Lugar legislation dealing with L'S as- effects measurements. mercial power reactor fyel. The base sistance to Russia in dismantling line ATW sysiein being considered nuclear weapons that have been elimi- incorporates a IhOO-MeV. 250-mA cvv nated in recent stockpile reduction proton linac thai drives lour hinh-lher- agreements. The proposal is for a study Accelerator Technology Division 13 Prut;nuns and Program Development • A Next Generation Hiifli-Power Neulron-Seatlerint; Facility {LANSCE II) The proposal noted that LAMPF is currently a 1 -MW facility with a very reliable coupled-cavity linae (CCL) section that comprises over 9O'/< of the linae. The proposal includes replacing the present 200-MHz front end with a 400-MHz radio-frequency quadrupole A new initiative is under study by a Los Hence, the conversion of LAMPF to a (RFQ) drift tube linac (DTD combina- Alamos National Laboratory (LAND high-power neutron-source driver is tion, both to increase reliability and to interdi\isional team, with strong AT very attractive, both in preserving the provide an upgrade path to even higher participation. This large project would present facility and in meeting national power. The beam (at 20 MeV) then greatly increase the capabilities of US research goals. Additionally, reusable enters a new 800-MHz DTL for accelera- neutron scattering facilities, including parts of the Itnac and the extensive tion to 100 MeV and matching to the the Los Alamos Neutron Scattering infrastructure built tip over the past 25 present CCL. This arrangement enables Center (LANSCE). LANSCE now years would substantially lower the tunneling at the 20-MeV level for an pro\ides the world's most intense burst construction cost and effort of such a upgrade to 5 MW of beam power as of neutrons for research in a wide range spallalion source over a "green-field" shown in Fig 1.11. No upgrade of the of condensed-matter topics and facility. The notion of emphasis on CCL rf power is required in the I-MW biological studies. A nominally 1-ms neutrons at Los Alamos is not new: case because the Itnac presently carries II macropulse t oin the Clinton P. several years ago AT personnel, in a current at this level (at 120 Hz) and Anderson Meson Physics Facility study known as LANTERN, suggested hence provides the same average power. i LAMPF) containing some 3 x 10" that the future of the mesa was in Additionally, by doubling the front-end particles is accumulated for about 2500 neutron production and advocated this frequency, the charge per bunch is turns in the Proton Storage Ring (PSR) direction for several purposes, includ- actually reduced from the present and is ihen delivered to a refractory ing waste transmutation, defense LAMPF operating conditions. metal target in a 200-ns burst to applications, and energy production as produce the desired spallalion neutron well as neutron scattering. Most of the We designed an accumulator ring with pulse. The net beam power to the recommendations of that study are now achromatic bends and a 140-m-circum- target approaches SO kW. A rival under active pursuit by the Laboratory. ference "race-track" configuration for the source. ISIS, operates at the Rutherford I-MW case. The achromatic bends Laboratory in the United Kingdom, and In August 1992. a site visit by the promote a high degree of linearity lhat is other smaller spallalion sources Department of Energy's Basic Energy undisturbed by chromaticity corrections. throughout the world accommodate a Sciences Advisory Committee Injection is accomplished by single-stage large community of neutron scattering (BESAC) provided us with the oppor- foil stripping and phase-space painting is workers. Such pulsed-spallation tunity to present our proposal. A planned. There are many issues in the sources pro\ ide a much higher peak conceptual design for a 5-MW facility required accumulation of over ID14 neutron intensity (though less average had been proposed internally and was particles in the ring (several times lhat intensity i than do nuclear reactors quickly augmented with technical detail successfully accumulated in the PSR). designed for neutron research. Hence. as well as a preliminary cost analysis. We will draw heavily on the lessons although reactors are useful to neutron Presentations were made by AT, learned in the PSR studies to increase scattering work, they lack the pulsed LANSCE. and Medium Energy Physics storage capability. Beam losses and the character essential to much of the (VIP) personnel to the committee. electron-proton instability are particular research. Shortly thereafter, a Los Alamos issues encountered in the PSR to which contingent was invited to a workshop in we must pay close attention. Because of Recent interest has arisen regarding i 'hicago. held in conjunction with the the increased ring size, the resistive-wall sources of substantially greater neutron BESAC committee site visit to instability, unimportant in the PSR. will intensity lluin that of LANSCE. The Argonne National Laboratory, to dominate and active damping will be European community has undertaken a present our proposal to the BESAC required. A sophisticated rf system using 2-\ear study lor a 5-.MW spallalion accelerator subcommittee. Again, a several harmonics will also be required source that would exceed existing crash effort was mounted that led to a to keep the beam longitudinally confined reactor average intensity. Discussions more detailed design and cost assess- to provide an extraction gap. When we within I.os Alamos this spring provided ment. The presentation went smoothly include the sophisticated bump system impetus for a similar proposal from the and appeared to he well received, for injection painting and an extraction Laboratory. In particular, funding tor thanks to a great deal ol effort by kicker, it is clear that the ring requires 1 LAMPI- as a nuclear physics facility is numerous individuals in the Division. extensive pulsed-powcr implementation. scheduled to end with FY I'W.i. 14 Accelerator 1 ethnology Division Programs and Program Development • A Ne.\t Generation High-Power Neutron-Scattering Facility (LANSCEII) Added • Existing before equipment upgrade 30 mA 400 MHz RF H' injector ~ Q • o o o o oSoati°onSo o o o 10JflM0 u»s 1 Compressor RFQ 800 MHz 800 MeV, 1.25 mA 75keV 65 mA H" injectors O© 0© 100 us 3 Compressor \ co oo o 000000000000000009 nnn Rinas HI ' ©0 0 0 Funnel 5 MW Fig I.I I. Upgrade path for LANSCE II. The I-MWcase is shown at the top. In a 5-MW scenario, a funnel at the 800-MHz DTL is completed and the rf power throughout is doubled. After one-turn extraction from the ring, • chopping the beam on a 1-ms time References the highly compressed beam pulse is scale to leave a gap for extraction in conducted to iwo target stations, where the ring, 1. A. Jason, R. Hardekopf, neutrons are produced by beam ' current carrying ability of the CCL, G. Lawrence, R. Macek, R. Pynn, and impingement on a refractory metal • ring stability and storage time, G. Russell, "LANSCE —The Los target. The neutrons interact with • system reliability, and Alamos '1-MW' Spallation Source," energy-moderating materials and then • system particle losses and activation. Spallation Source Workshop, Chicago, pass through holes in the shielding IL, September 1992, Los Alamos surrounding the target for use in a wide Some of these issues lead us to con- National Laboratory document variety of instruments. The LANSCE clude that a higher energy (up to 2 LA-UR-92-3497. staff will now study the high-intensity GeV) would be helpful because the target design and develop plans for a current needed to produce thi- required research facility. power is decreased and ring stability is enhanced. Such an option would The upgrade to 5 MW would require require either an afterburner linac or doubling the rf power throughout the replacement of the CCL. In either case, linac and increasing ion-source a superconducting linac provides an intensity to 100 mA as well as complet- attractive option. ing the funnel at 20 MeV. Two additional rings would be required for We expect to have a preliminary design sequential accumulation: storage in proposal ready for August 1993, which each would be increased by almost would position us for possible con- 70%. The parameters of this upgrade struction funding in 1996. Our initial are very stressing and we must prove estimates for the 1-MW-scenario that they are attainable. The major construction cost are over S500 million; issues identified so far include the planned upgrade would cost an additional $340 million. Accelerator Technology Division 15 f'i,n;runi\ ,iiul l'rn\;nii>i .I:\I\KI. (>MI(i.\ c. i. ,uht In w \CIIIIPII Scm, c h>i \lulfiti A majoi new cousiileialion in aecel eialoi lcchiiolo;j\ loi an 11 -' \ 111 - was JAERl OMEGA Project and proposed lo the coniniiiuiiy by the tune I1MI1 consiiiiction inij.'hl beyin. Intense Neutron Source for Materials Testing supercondtictim; (S('i accelerator casilics m11_'IIt be the preferred technology in technical and cost terms. JAKKI OMECA Project Intense Neutron Sources for j if a thorough I\\V1> piojjraiu was I Materials Testing I supported belore Imal counuiiineiil lo i an S(' approach was made. Al The Japan Atomic laiergy Research Work lor the IH)|7()lVice ol' lusion j present. SC rl ca\ilies ami inaunels are Institute I.I.\1-RII continues us ! beiii;j. used in many new accelerator OMIXiA Program activities in I lie ; l"uer;j\ (OIT'i eoniiiuied duriiu; I A \K>1>2 as the niaterials coinmumlx laid I insiallaiions and arc hcjiiiiuiiij: to evaluation ol new options loi disposing ' pro\e then reliahilils and cost ot radioactive waste, and again the yroimdwoik lor tnakinsj an iiilcrna lional pioposal. Meelittiis ol'lhe ; el'lecit\eiiess. I'he \er\ hii;h inlciisilv pros ided funds lo A I'-l)i\ ision lo '. inachiues under coiisuleratiou in AT international comnuiiiiu realliiiiictl the ] e\plore system layout and optimization ' I 'i\ isiou add another dimension; candidacy ol'the |)-l.i (deuieron foi the IdOOMeY. Ill-Ml inA o\ Ituac • because hi If) At it' Programs and Program Development • Advanced Free-Electron Laser Initiative (AFELI) Introduction The Advanced Free-Electron Laser Initiative (AFELI) is funded to support high-quality basic and applied research in the field of Advanced Free-Electron Lasers (AFELs) and to demonstrate these advanced technologies. AFEL research will provide an understanding of the performance and engineering limits of free-elecixon laser (FEL) systems, thereby strengthening the science and technology base for existing and future Laboratory and national FEL initiatives. The goal is to build a second-generation FEL system to research and develop advanced components. This system will incorpo- rate state-of-the-art components and be friendly and robust. Research and developmental areas include the Fig. 1.12. Permanent magnet wiggler. various subsystems of the FEL: the electron source, accelerator, vviggler Description magnet array, optical system, diagnos- i.cv and control system. State-of-the- The present design of the compact FEL current of 10 kA to generate a magnetic yrt components include ultrabright. consists of a high-brightness accelerator field up to 5T on-axis. The length of high-gradient, low-loss accelerators: and a microwiggler. The electron the optical resonator is 1.4 m. Includ- electromagnetic microwigglers: source is a laser-driven photoemitter ing operation at higher harmonics, the emittance-preserving magnetic that produces 2-nC and 10-ps-long laser wavelength extends from 7 um bunchers: and advanced optical micropulses at a rate of 108 MHz. The down to 0.4 um. resonators. This second generation of macropulse is 20 us long and has a r te FELs. referred to as compact FELs of 10 Hz. The electron beam is acceler- because of their size, has many ated to 20 MeV by a 1.2 m on-axis potential applications in industry, coupled structure operating at 1300 medicine, and research. MHz with a field gradient of 22 MV/m. The accelerated beam has excellent beam quality with a transverse emit- tance of less than 3 -mm-mrad and an energy spread of 0.3%. Two types of wigglers will be used: a permanent magnet wiggler and a pulsed-current wiggler. The permanent magnet wiggler (Fig. 1.12) has 24 I-cm periods. The peak magnetic field is 0.4T on-axis. The pulsed-current microwiggler (Fig. 1.13) is l()-cm long with a 3-mm period and has a slotted tube design. It is driven by a pulsed dc Fig. I.I.I Pulsed-current microwiggler. Accelerator Technology Division 17 rograms and Program Development" Advanced l-rec-Klcitron l.ii\ci Initiative I Ml-.l.h The experiment will use the control system developed by ATS. This control system will he used initially tor monitoring system parameters. Later in the program, the control s\stem will he used tor active control. I'ii;. I.14, Hra:ett copper limn- structure for tin mlvaiiced I'EL Untie. .i... /•'a;. 1.15. Al•£/. electron bcuiiiliiw. The HHL. I'aeilily is at Meson Physicx Facility. Technical Area 53, building 14. The accelerator and FHL are so compact that they can be housed in a 12 ft \ 25 It vault. The accelerator structure has been fabricated (Fig. 1.14). and schematic of the AFEL experiment is shown in Fig. 1.15. The heamline. shown in Fig. 1. Id, consists of permanent magnet i|uadrupoles and dipoles: permanent magnet elements are used to improve reliability and compact- ness. The permanent magnet wiggler has been constructed, and the pulsed tube wiggler is under construction. The first beam was obtained in June of IW2; the first FF.l. operation is expected in the spring of 11W. I'ii;. 1.16. Curl Timiiwr Ibtickxromul) tnul Steven Kniiji {postdoctoral fclhws) work on ilie All:!.. Hie accelerator i.\ in the background: the electron hcanilinc with /•'/•.'/. oplii\ ore on tin' optii'al table in the [orcxroinul. I.S Accelerator lechnolo^\ Division Programs and Program Development • Superconducting Super Collider (SSC) During 1992, several groups in AT In the low-energy booster (LEB), AT-7 Division were involved in providing has carried out beam-dynamics support to the Superconducting Super calculations to better predict and Collider (SSC) Laboratory near Dallas. control the effects of beam loading in These activities are summarized here the rf cavities. AT-5 collaborated with and covered in more detail in the SSC in the design of the perpendicular- specific groups involved. biased ferrite-loaded rf cavities that must swing from 47.5 to 60 MHz in 50 In the SSC linac area, AT-1 has msec at a 10-Hz repetition rate. AT-1 designed, fabricated, and delivered a 4- is also providing rf-cavity design vane, 2.5-Mev, 428-MHz radio- support. AT-3 and AT-5 provided frequency quadrupole (RFQ) to SSC. modeling support in the design of the AT-5 fabricated a tetrode amplifier for 10-Hz resonant-circuit ring magnet this RFQ, which SSC has coupled 10 system. AT-3 is consulting with the and successfully tested on the RFQ. Accelerator Diagnostics Department AT-1 has continued to provide support on the diagnostics design. Similar in the cavity design for the 1284-MHz support in all these areas is being coupled-cavity linac. Additionally, AT- provided for the two other booster 1 provides beam-simulation support to rings. the SSC Linac Group on an as-needed basis. AT-3 is modifying the design of In the collider rings, AT-3 provided some adjustable-gradient permanent- support in the prediction of the magnet quadrupoles developed for the transmission-line modes in the long Ground Test Accelerator (GTA) that strings of superconducting magnets. will be used in the SSC RFQ-to-drift Because the superconducting magnets tube linac (DTL) matching section. form a nearly lossless transmission These quadrupoles are very compact in line, power supply ripple can propagate comparison to equivalent electromag- long distances with little attenuation net designs. In the low-level rf area, and lead to emittance growth. AT-3 AT-5 continues to work closely with has proposed a way to damp these the SSC rf group to provide a low-level traveling waves and limit the magnetic rf control system, using development field ripple to less than 1 pan in 109. work done for GTA. In the accelerator controls area, SSC critically evaluated several control systems, both commercial and in use at other national laboratories, and selected the AT-8-designed Experi- mental Physics and Industrial Control System (EPICS) to be the baseline control system for use on all accelera- tor systems at SSC. EPICS is also being used in the GEM detector collaboration. Accelerator Technology Division 19 Programs ami Program Development • The High-Power Microwave (HPM) Program The main thrusts of HPM program development have been to participate actively in national HPM program management and to detect and pursue opportunities to apply the division's unique capabilities to HPM problems of national importance. HPM program management is intended to ensure AT Division maintains a program The DoD has long been concerned effective technical and financial management and program development about the accidental adverse effect of execution of programs, once funded, effort in high-power microwaves HPM on military systems, such as that and to conduct sponsor liaison. To (HPM) on behalf of all organizations at aboard modern naval ships where learn about the technical work per- the Laboratory with expertise appli- nearby systems can interfere with one formed in this area, the reader is invited cable to that technology. Laboratory- another. With the growing possibility to review the section of this report that wide program management of HPM is of intentional interference or destruc- covers Group AT-9. resident in AT Division because of the tion by a microwave weapon, this substantial concentration of the concern has multiplied and resulted in expertise in the division. Other extensive programs to understand the divisions currently involved are A, vulnerability of US military systems to CLS. IT. M. MEE. MST. P and X. HPM. A related interest in HPM This section presents an overview of effects resulted in funding by the that effort, which is described in detail Department of Energy (DOE) and its under AT-9 activity since virtually all predecessor agencies as well as the division work in this area is conducted DoD because of the importance of the in that group. "electromagnetic pulse" from nuclear weapons. Again because of the It has been recognized from the earliest availability of unique rf sources, days of radio that electromagnetic instrumentation, and facilities, the radiation (EMR) at rf wavelengths has Laboratory and division have for many potential as a weapon. Although years participated in these vulnerability technology did not effectively support programs. this application of EMR until recently because of limitations on rf power at Future generations of high-performance appropriate wavelengths, it has now- rf accelerators will require amounts of become feasible to use EMR to disrupt rf power well beyond that available or destroy military electronics at useful through a reasonable number of current ranges. Vulnerability considerations technology sources. Thus, a strong have shown that the appropriate source-development effort is an wavelengths are in the microwave important part of the nation's rf regime. Various agencies of the accelerator program. Work on ad- Department of Defense (DoD) have vanced sources for this application has active programs to develop HPM also been an important part of the weapons. The Laboratory and division division's past HPM activity. have participated for a number of years because of the unique capabilities here and because of potential synergism with accelerator applications within the Laboratory mission, as noted below. 20 Accelerator Technology Division i /triv/n/imrm • \iiilitil I'tulh If Hfiini I \l'Hl I'uwcr S\\li'in\ HivhHi;hl.\ has been dev eloped hv ALCOA and thev have achieved a puriiv ol Neutral Particle Beam (NPB) W.wy.i'i. VS'hen operated at 20 K. the vv ire has characteristics similar to a Power Systems Highlights superconductor vv ithoul the trouble- some problem ol quenching. By using high puritv aluminum vv ire in the 1 L construction ol the alternator, not only During calendar year 1 > >2. work has cooling scheme. The cooling scheme is wire weight saved, but losses are cuniiiiiied m ihe Accelerator lechnol- chosen was developed al Lawrence greatly reduced, vv hieh decreases the onv Division on ihe Direcied hnergy l.ivermore National l.ahoralorv and is cooling requirement. All these things Weapon l\>\ver Integration called a nucrochannel heal sink. The reduce the si/e of the alternator. The ,DH\\ POINl i power program. iransistor chip is bonded in an alumi- current estimated specilic weight of an I nlonunaiels. .1 MibManlial decrease m num nitride substraie. which is in turn, alternator using this technology is less program iuiidiiiLj caused a reduction in bonded to a silicon uucroehannel heat than II. 1 kg/k\V. the number of technologies ilial could sink. The heal sink has main narrow he pursued. grooves through which the coolant passes The cooling capability is ALCOA has successfully fabricated In the orii'inal Dl-W I'OIN I pr.>graiu. gieallv enhanced because ihe fins SOD feet of rectangular high purity there was .1 dual path tor all critical created hv ihe cutting process greatlv w ire: the vv ire is 0.16 in. square. technologies, h was planned 10 puisne increase the cooling are.! and the width Because high purity aluminum is very two sources lor rl power the kly strode, ol the channels are less than the soft, the vv ire undergoes an involved a vacuum tube composed ol gndded laminar laver thickness ol the fluid fabrication process thai includes being tube input structure and klystron output passing through them. draw 11. This requires the wire to be structure, and a solid-state anipliher. clad w ith a shell of Al-Fe-Ce for Similarly, two sources ol prime power Testing of the initial HAM is scheduled strength. There are many potential were also heing pursued. The for the xpniii! of IW: with final HAM applications for this technology in hv pei'Lonductin^ alternator was the testing scheduled lor the summer. transformer and rotating machinery primal \ thrust with the hihium-thiony I- design where superconducting charac- chlonde halterv hem;: Ihe backup tor Success! ul operation of ihe teristics are desirable. One need not use hydrogen for cooling: either neon short mission times livperconducling alternator requires or helium miiihi be used. hiuh purilv aluminum w ire. This wire Bu.'uv o| ihe tundui'j cuts, ihe program was reiluced to solid siak aniplitiei ilc'.elopiiicnt with a hvpeKoiuluctiii'j .illcriialoi as the prune pov.cr source \u ainhilioiis pio'jiam 4.260" was undertaken lo dcel.ip a hv hnd amplifier module ' II Wl 1 a! >^> Ml 1/ 1 lie output pov er from this module is 0.250" designed 10 he ! k\\ and the module 'ACI-J.II! 1- cMllilaled .it ''II u I he HAM js io be the Ki-it. hi 11 Mini: block I or .1 5< M 1 k\\ .imphliei I ach II \M '••>•< uld li.iv c U' -o!id siale !i,.i,lc • SS 1 1 t hip* 2.500" I he solh|.s|,,!e i! 1. iik ;s ,111 II 1 Iv pe dev kv w nh \ I . i 1.1; a-, lei'1 -Ik • mikh like me •. iii'. •'- o1 'he . 1. uu'ii !n. nle I he II \'\1 -l:o h,,s h ii' mpul -piillei v. !K lull'. and llie 1 nil|iiil •-' 'mhmei . ii"> mil •• a- •.-, eii 1- ihe heal / '• . , / //•. !<> 1,1 iUlifiilflt I Hit ulllli -II1K I' ..an I">L apple, lale.i thai Hie pi >w el ileii -il-. m llli- mi ulule h hi'jli. w hk h pl.ii.e- a -evele biuden 1! ii ilk- Ai < clcmlor Ti'c/tiit'li>t>r Division Programs and Program Development • Industrial Partnering Low-Energy Proton Accelerator Sys- tems for Medical Applications: AT-1 has united with Neutron Technologies and more recently with Babcock and Wilcox to develop Boron Neutron Capture Therapy. Similar ties may also be created to develop commercial sys- Over the past years, rapid and extensive During FY 1992, AT Division began tems for proton therapy. changes in global politics have clearly transitioning some of its projects to be indicated that weapons research is no more aligned with the commercial and Frequency Agile and Compact FEL longer a top national priority. National industrial sector. Examples of such Systems: We are identifying programs security and well-being are now more activities and identification of the rel- to develop such FEL systems with dominated by issues of economic com- evant industrial partners follow. Grumman Corporation as the industrial petitiveness. These changes have caused partner. The most noteworthy applica- AT Division to recast its business strat- EPICS: The Experimental Physics and tion for such a system is in naval ship egy so that greater breadth is added to the Industrial Control System (EPICS) de- defense in which the sensors of incom- previously concentrated focus on accel- veloped by AT-8 has been united with ing cruise missiles will be defeated. erator-based advanced weapons systems. Titan Industries and Tate Systems. They Examples of such programs are the Stra- will adapt the EPICS software package Permanent-Magnet and Soft-Magnetic tegic Defense Initiative Organization to control problems in the commercial Material Development: AT-3, with (SDIO) support for missile defense sys- marketplace. Applied Materials Corporation, has tems using neutral particle beam (NPB) p:;ipused to develop advanced mag- and free-electron laser (FEL). An oppor- Klystrode Microwave Tube Develop- netic materials for use in accelerator tunity to broaden our market for accelera- ment: AT-5 joined with Varian Industries structures and controls. tor technologies has occurred through the to commercially develop high-power, Department of Energy's (DOE) and De- high-efficiency microwave klystrons for Plasma Processing Systems for Ion fense Programs" sponsored Technology the communications marketplace (e. g., Implantation: AT-5 will supply the Transfer Initiative (TTI). This TTI was high-definition TV broadcasting). modulator and microwave systems created as a "dual-benefit" program Clearly the benefit to AT Division is a needed by General Motors to develop whereby the DOE supports Laboratory less costly microwave power source ion-implantation on large volume and development projects that have aligned manufactured in the United States for irregular surface objects (e. g., car industrial support (i. e.. the industry sup- future accelerator projects (e. g.. Accel- engine blocks). ports its own personnel and facilities with erator Transmutation of Waste |ATW| "in-kind" resources project development and Accelerator Production of Tritium Accelerator Based Conversion: This activity). The dual-benefit realized is (1) [APT]). most ambitious program development industry is the beneficial recipient of the has as its industrial partners Grumman, Laboratory's advanced technologies and Low-Level Radio-frequency {rf) Westinghouse, and Bechtel Corpora- competencies with the goal of becoming Controls: AT-5 has also found an indus- tion. The activity involves marketing more competitive in the high-technology trial partner, Kinetic Systems, to market accelerator systems similar in perfor- marketplace, and (2) the Laboratory is its low-level rf control units. mance to APT, but whose function is to the beneficial recipient of transitional drive a neutron source that converts financial support allowing for develop- Electron Beam-Plasma XUV Source: weapons plutonium or other fissile ment of new technology markets. Al- Grumman Electronic Systems and Etec material into a nonweapons grade iso- though the most visible, TTI is not the Systems, Inc., have joined with AT-7 to tope. An upgrade of such an accelerator only avenue available by which to pursue develop a unique extreme ultraviolet or based conversion (ABC) system could industrial partnering. Additionally with soft x-ray (XUV) source with applica- even "burn" the fissile material to the change in governmental administra- tions to semiconductor lithography. produce energy. tion, there will assuredly be increased incentive for the Laboratory to engage in Microwaves for Chemical Processing: The formation of these industrial part- industrial partnering as a way to DuPont has paired with AT-9 to develop nerships does not guarantee that all will strengthen economic competitiveness. high-power microwave systems that receive DOE funding. However, we This was reflected in the Laboratory facilitate chemical processing either by expect the number of AT-Division ties Director's definition of industrial bulk heating or by inducing catalytic with industry for the purpose of com- partnering as a strategic thrust area that is reactions. mercializing accelerator technologies to projected to grow to 2()c/r of the increase in the coming years. Laboratory's budget. Accelerator Technology Division Programs and Program Development • Industrial Partnering Accelerator Technology Division 23 w, li \ Technical HixhliRlus • AT-1 • Accelerator Physics and Si>ccial Projects Introduction 27 Accelerator Projects 27 Ground Test Accelerator Project Su/>/>ori 27 Photoinjector l.itutc for the Advanced Free-Electron Laser lAFEL) 27 Radio-Frequency Quudrupolc Linuc for the Superconducting Super Collider 2H Side-Coupled Linuc for the SSC 2 Beam Dynamics 29 Effects of ij "transients in the CCLfortheSSC 29 Desifiii and Simulation of a liridi>e-CoupledDTLfor Accelerator Trunsmuialion of Waste 31 Superconductivity Strong-Focusing RFQ .' 32 RFQ Linear Accelerator for PET Isotope Production 32 POISSON/SUPERFISH C 'ode Development for PC Compatibles 32 Si met tires Development Lahoraton 33 Cavity Development Activities 33 Achievements 34 Technical Memoranda 36 Accelerator Teeliniiloifv Division Technical Highlights • AT-1 • Accelerator Physics ami Special Projects Introduction so that they may eventually share about 2. In addition, the thermal photocathode production and transport expansion coefficient is lower and the The AT-1 Group, Accelerator Physics systems. thermal conductivity higher at those and Special Projects, provides accelera- temperatures. These three factors tor design and physics support for The AFEL linac differs from its two contribute to the possibility of a much various AT Division projects. The staff predecessors primarily in final energy higher rf duty factor than is otherwise at AT-1 also pursues advanced topics in (20 MeV, 11 accelerating cells versus 6 possible without direct nose cooling. accelerator physics and technology. MeV, 6 accelerating cells) and in its More subtle improvements have been Additionally, AT-1 builds small capability for cryogenic operation. The made in the form of larger focusing and accelerators for special applications. system can be cooled with either liquid bucking solenoids and in the number What follows is a summary o\' the nitrogen or water. The copper rf and orientation of the coupling slots various AT-1 activities for the 1992 structure is thermally isolated from its that connect the accelerating cavities to fiscal year. surrounding vacuum vessel, allowing in the on-axis coupling cavities. These situ rf baking to achieve the high improvements are expected to result in Accelerator Projects vacuum (<1 x 10~g torn required by the the brightest electron beam source yet. cesiated photocathode. At tempera- Ground Test Accelerator Project tures approaching 77K, the electrical The photoinjector linac was delivered Support resistance of the copper is expected to in FY 1992 and has been operating at be significantly lower than at conven- ambient temperature. Tests of cryo- The design of low-energy and high- tional operating temperatures, produc- genic operation are planned for FY energy end walls for the ten Ground ing a quality factor (Q) enhancement of 1993. Test Accelerator (GTA) drift tube linac (DTL) tanks was completed during FY 1990. These end walls are cryogenically cooled, brazed-copper units. The end walls for tanks five through eight were fabricated and tested during FY 1991. The remaining two units were completed during FY 1992. Photoinjector Linac for the Advanced Free-Electron Laser (AFEL) Under funding for the Experimental Research and Development Initiative and in conjunction with AT-7. we completed a 1300-MHz. 20-MeV photoinjector linac for the Advanced Free Electron Laser (AFEL). This unit Fig. 2.1. Schematic of U00-MH:., 20-MeV cryogenic linac for the AFEL. (Figs. 2.1 and 2.2) is now in laboratory service. In many ways, the AFEL linac is similar to both the 6-MeV high brightness accelerator FEL (HIBAF) (FY 1989. now APLE prototype experiment [APEX]) and the 6-.VleV National Center for Laser Research (NCLR) (University of Twente. FY 1991) photoinjector electron linacs. Like them, it is a compact, brazed- copper. on-axis. coupled, radio fre- quency (if) structure. It employs the same photocathode hardware as APEX. Fig. 2.2. Brazed copper, on-axis, coupled linac for the AFEL. Accelerator Technology Division 27 Technical Highlights • AT-l • Accelerator Physics and Special Projects Radio-Frequency Quadrupole Linac for the Superconducting HIGH Super Collider ENERGY END The 2.5-MeV, 428-MHz radio- frequency quadrupole (RFQ) for ihe injector of the Superconducting Super Collider (SSC) facility was delivered to the SSC Laboratory during the summer of 1992. The RFQ PICI'dP LOOPS 141 (Figs. 2.3 and 2.4) is a two- FIXED SL.UO TUNERS 130' segment, continuous-cavity MO-SECTION FLUJCE structure 2.2 meters long. Each segment consists of four vane/cavity quadrants joined by eleclroforming. LOW This is the technique ENERGY END developed for "he Beam Experiment Aboard a Rocket (BEAR) RFQ and was also Fig. 2.3. Schematic of the 2.5-MeV. 428-MHz radio-frequency quadrnpole (RFQ) linac far utilized for the Continuous-Wave the superconducting super collider (SSC). Deuterium Demonstrator (CWDD) RFQ. It was manufactured jointly by LANL and GAR Elcctroformers of ^ \ Danbury. CT. Side-Coupled Linac for the SSC We are carrying out the detail mechani- cal design for the side-coupled linac (SCL) (Fig. 2.5) for the SSC. It is a 1284-MHz structure consisting of nine modules, each with eight accelerating tanks (72 total) joined by bridge couplers (63 total). This is a graded-P structure and will be described on 1400 mechanical drawings. The drawings are being produced by a CAD program- ming technique that allows the physics dimensions of the accelerator and bridge tanks to be read from data files so that the detail and assembly draw- Fig. 2.4. Final assembly af2.5-MeV, 428-MHz RFQ linac for the SSC ings can ihen be generated. This (front-left: Dale Schrage. Lloyd Young, Phillip Roybal, Felix Martinez. Angela Naranja; rear-left: William Clark. Roy DePaula, Jim Billen, Doug Aikin). method will provide considerable savings in cost and time. The SCL will be a bra/ed-copper structure, fabricated in the Peoples' Republic of China. 28 Accelerator Technology Division Technical Highlights • AT-1 • Accelerator Physics and Special Projects Low-Power Tuning ofDTL Cavities field distributions in rf cavities. Beam Dynamics for the GTA Development work began in 1984 for 8086-based computers. The codes Effects of rf Transients in the CCL We have tuned the first five of ten 850- now run on 486 and 386 PCs and for the SSC MHz DTL cavities for the GTA. include extensive on-line documenta- Tuning included low-power measure- tion. The programs BEADPULL and Each module of the CCL for the SSC ments of the following: ramped field QUADPULL collect frequency shifts consists of 8 tanks with 16 accelerat- distribution, field stability, cavity Q, as a metal or dielectric bead traverses a ing cells each. The tanks are coupled and coupling to the rf power source. resonant cavity at constant speed. with bridge couplers. The rf power Before post couplers were installed, the QUADPULL measures fields in all drive is in the center of the module at unstabilized field distributions agreed four quadrants of RFQ cavities. the bridge coupler between the fourth with predictions based upon Analysis codes apply the Slater and fifth tanks. In simulations of the SUPERFISH code calculations and perturbation theory to convert fre- beam dynamics, the if power is turned applications for the Slater perturbation quency shifts to fields. BEADPLOT on 10 us before the beam is turned on. theorem. We adjusted and stabilized plots the field distributions and This time lapse allows the fields to the relative field distributions to within calculates field integrals. DTLPLOT build up and stabilize before they are ±0.25% of the design ramp. The low- analyzes and plots the results of axial required by the beam. When the beam power measurements also included the BEADPULL measurements in DTLs is turned on, the beam loading causes Q enhancement and the field distribu- or coupled-cavity linacs (CCL). the fields to change. This transient tion at cryogenic temperatures. There QUADPLOT does the same for state of the fields, together with their were no significant changes in the QUADPULL data in RFQs. Support- effect on the beam was studied. We relative field distribution at cryogenic ing programs such as BEADPLOT, developed a model to calculate the temperature. The room-temperature Q DTLPLOT, and QUADPLOT prepare field distribution throughout the was typically 75% to 85% of the design data for comparison with the module as a function of time. We then SUPERFISH Q, and the cryogenic Q measurements and compute averages ran beam dynamics simulations with was about 3.2 times the room-tempera- of multiple measurements. Program the results of this model corresponding ture Q. COUPLING extends the accuracy of to different times during the macro- an impedance analyzer for Q and pulse, deriving an estimate of the Radio Frequency Measurement and voltage standing wave ratio (VSWR) effect of the transients from the results Analysis Codes measurements. The COUPLING code of these simulations. plots reflection coefficients on a Smith We have developed a comprehensive chart and analyzes the resonance circle The code TRAN6 calculates the field collection of computer codes for to get p. amplitude and phase of all the acceler- measuring, analyzing, and displaying ating cells versus time. TRAN6 displays a moving picture of the TAH Mechanical design for the side-coupled linuc ISCL) for the SSC. Accelerator Technology Division 29 Technical Highlights • AT-1 • Accelerator Physics and Special Projects In Fig. 2.6 the time has advanced to tl«e* U.TSusec. 10.75 (.is. The beam was turned on at uo uo 10 us. The amplitude in the tanks has UnM-5 99.15 phase* -B.Ueg. dropped \CA- to 2'>'<. The rf power has tank3-6 58,7V phase" B.5deg. increased because the feedback system tank2-7 98.37 phase' B.7deg. tanJtl-8 98.11 phase* B.Bdcy is requiring more power to compensate puf Iwlrp 1.45 phase* 1.97deg Average Amplitude for the beam loading. The rl" power V refpaM scale on the right side of the plot means percent of maximum klystron power. The simulation had proportional, J integral, and differential (PID) feed- ^•Forward Power back built into the code. This PID feedback on the rf power simulates a nearly ideal PID feedback control *N- system; however, no feedforward that '" "*"JK may be used on the SSC-CCL rf ^•AmplitudAmplitude of accelerating control system is included. cavities Reflected Power For beam dynamics simulation, we ••••...«.., t yAraplitude of couipi ing reuormalize the design values £,/ of the V_ •*••"••«, ....,.<£ cavltiea V4X awo woe iw.oo isn \«ux> I0WJ0 KM0 accelerating electric field in any given c As expected, the si/.e of the transverse root-mean-square (rms) beam (not -1.0 sh-iwn) during the transient stage does not change when compared with the steady state situation. However, the transient fluctuation in E,, causes phase- energy oscillations in the longitudinal phase-space, as shown in Fig. 2.7. The -1.0 I II I II I I I I 1 I I 1 1 I II 1 mean energy W, of the output distribu- tion deviates significantly from the .t steady-state value within the first t microsecond after/ = 10.0 us. At ' = 10.75 us, the mean energy deviation is = 559keV. At / = 1 1.50 us the 0 4 I II II !1 H II 12 K «0 « <• U H H H U 11 II conditions are virtually the steady state situation. No particles are lost at any Fig. 2.7. Energy profile \:s tank number at (a) I = lJ.'J5 jj.\. I hi I =10.5 fl\. Ic) I = 10.75 /Is. till I = 11.0 [bund (el t = 12.0 ys. JO Accelerator Technology Division Technical Highlights • AT-1 • Accelerator Physics and Special Projects time because of the transient effect. ratio of transverse aperture to rms BCDTL and the transverse phase- There is also no statistically meaningtul beam size has been used as a figure of advance per focusing period were emittance growth during the transient merit in estimating beam losses. In chosen to optimize the transverse ratio stage. The deviation in the Phase is not order to minimize beam loss, we have of aperture to rms beam size. significant. required this ratio to be 6 or larger above 20 MeV throughout the linac. Using a modified version of the Design and Simulation of a Bridge- This condition requires adequate PARMILA code, the BCDTL shown Coupled DTL for Accelerator Trans- transverse focusing throughout the in Fig. 2.9 was simulated from 20 to mutation of Waste linac to maintain beam size and to 80 MeV as 86 individual tanks with minimize emittance growth, which intertank quadrupoles for transverse Recent Los Alamos designs of high- could produce beam halo. The ratio of focusing. In this situation there is current, continuous wave (cw). proton aperture to rms beam size is dependent essentially no transverse emittance linacs for accelerator transmutation of on the intertank spacing and the type of growth. The longitudinal einittance, waste (ATW) incorporate beam focusing lattice used. The number of however, grows because of the tunneling to achieve desired levels of accelerating cells per tank of the constant accelerating gradient. This current, emittance, and if efficiency in the high-beta accelerating structure. Typical designs have a front end consisting of two 350-MHz linacs. each Funnel composed of an RFQ and a DTL, 700 MHz, 140mA which accelerate protons to 20 MeV. The two beams are funneled into a 700- Injectors MHz CCL that has a final energy in the range of 800 to 1600 MeV. The design 80 MeV 800 MeV choice for a 700-MHz accelerating 20 MeV structure in the 20 to 80 MeV region 2.5 MeV would conventionally be an Alvarez 75keV DTL with permanent-magnet quadru- poles (PMQs) in the drift tubes. Fig. 2.N Schematic diagram of an ATW-type accelerator. The BCDTL would he used to However, for high-current cw applica- accelerate the beam from 20 to SO MeV after the beam has left the funnel. tions, the threat of radiation damage from beam loss makes the use of PMQs undesirable, and 700-MHz drift tubes 20-MeV Bridge Coupled Drift-Tube Linac Module (700MHz) cannot accommodate electromagnet Weight: Approx 3000kg quadrupoles (EMQs). The initial Power: 1.08 megawatts Coolant flow: 100 gal/min design approach was to begin the 700- bridge coupler MHz CCL structure at 20 MeV. quadrupole magnet Recent engineering analysis has shown _ 3-point kinematic that fabrication of such a structure at \ oupport quick release low-beta values would be complicated \ flange ' beam and power efficiency would be low. diagnostics We have derived a modified DTL valve concept, the bridge-coupled DTL (BCDTL). that provides an attractive solution for the problem region, with simpler fabrication and higher effi- ciency. Figure 2.8 shows a schematic- diagram of an ATW '; ,ie machine. The tunneling energy is set at 20 MeV because of increased engineering complexity; stricter beam dynamics requirements at higher energies, i.e.. \St beta LAMBDA DTL tank higher deflector fields and increased (no quads in drift-tubes) number of funnel components; and the 4 cm aperture desire to minimize beam-loss-induced activation at the transition region. The Fig. 2.'J. Conceptual engineering drawing of what a four-tank module of the IK DTL might look like. Accelerator Technology Division 31 Technic us • AT-1 • Accelerator Physics ami Special Project* constant accelerating gradient allows procedure, of an 11-MeV RFQ for basic feasibility ol the idea. We are the longitudinal focusing per unit radioisotope production for positron- also fortunate thai, at this frequency, length to become weaker as a function emission tomography (PET): (2) the rl power sources are commercially of distance along the linac. Nonethe- completion of the cavity design for the available for both the normal and less, there appears to be no effect ol 30-cm long niobium prototype cavity; superconducting cases. The next step longitudinal emittanee growth on the (3) establishment of the mechanical would be to produce an optimized transverse ciniltance. Such an emil- design (Fig. 2.10) for the prototype design and build a prototype accelera- lancc growth could result in a degrada- cavity; (4) fabrication of the niobium tor to demonstrate the concept. tion of I he ratio of the aperture to mis cavity parts and stainless-steel fixtures beam si/.e. for an electron-beam weld test; and (5) POISSON/SUPERFISH Code basic beam physics studies, including Development for PC Compatibles The results of this study indicate that measurements and analysis of the the BCDTL could be a practical output beam from the world's highest- We have adapted the POISSON/ alternative to a CCL for the 20- to 100- intensity RFQ at the European Center SUPERF1SH codes to run on 486 or MeV energy region of an ATW for Nuclear Research. 38b PCs. The PC version includes accelerator. This type of structure features not found in the standard provides adequate transverse focusing RFQ Linear Accelerator for PET version. These extra features include of high-current beams as needed to Isotope Production (1) control programs for automatically control beam-loss-indueed structure tuning RFQ. DTL, and CCL cavities; activation and is electrically efficient in We have developed a new concept for a (2) a complex version of the if field this beta regime. compact 11-MeV linear accelerator in a solver FISH: (3) memory allocation for single 3-m RFQ structure. This new temporary arrays; (4) many line regions Superconducting Strong-Focusing concept should be an attractive choice for dividing the mesh into fine or RFQ for a radioisotope-production accelera- coarse sections; (5) full support for tor for the PET application. We have multiple-cell DTL cavities; (6) plot Our objective is to develop a niobium, investigated two options: (1) a normal- files for displaying resonance-search superconducting. RFQ particle accel- conducting copper RFQ. thai would and transit-lime daia; and (7) on-line erator for high-field operation. This operate in a pulsed mode and (2) a documentation. We modified development would enable us to build superconducting RFQ that would AUTOMESH extensively to generate very compact low-velocity if ion linacs operate in a continuous (lOO'/i duty self-consistent logical and physical with energies up to about 10 MeV for factor) mode. The design concept coordinates. This new, more-robust protons and with the capability for includes a new approach, based on the code greatly reduces the number of accelerating high-beam currents. The recent RFQ that was built for the SSC crashes in LATTICE crashes that project represents a new application for application, that uses a ramped voltage previously were caused by ill-formed if superconducting accelerators. to maintain high accelerating fields mesh triangles along boundaries. throughout the structure. This results Program FISH detects and corrects Our approach is to (I) determine the in a very compact accelerator. Beam- potentially poor placement of the best parameter choices for the design of dynamics calculations for an driving point. Programs AUTOMESH, high-field superconducting proton unoptimi/ed design demonstrate the LATTICE. FISH, POISSON. SFO. RFQs: i2i identify the superconducting RFQ applications that appear to be most attractive, especially those thai represent a good entry point for a phased development of the technology; 131 design and construct a prototype superconducting 4-vane cavity, and operate H a! the highest fields possible: and (4l increase our understanding of ihe beam physics of high-current RI-'Q accelerators in order to enable us to lake ma\iimiiu advantage of the new technology we are developing. Progress during the past year includes i I I RI-'Q beani-dviKi^ncs design studies that include the di"-i jn. usina a new /•/I;. - '". The \upen -oinliu /mi; HI(J i a\il\ protot\j>e. Accelerator Technoltiftx Division Technical Highlights • AT-1 • Accelerator Physics and Special Projects and VGAPLOT return DOS exit-error Structures Development The design frequency of the accelerat- codes for use by control programs. The Laboratory ing structure matches the Los Alamos DOS exit-error codes solve arbitrarily Meson Physics Facility (LAMPF) large problems, limited only by Cavity Development Activities frequency of 805 MHz. In Previous computer resources. Each program fiscal years we concentrated our work allows free format entry of CON array At the structures laboratory we concen- on smaller 3-GHz cavities in order to elements, and provides error checking trate on superconducting accelerator establish an initial database and of the user entries. Our new root finder cavity development. This effort is develop cost-effective handling and convergence criteria have been directed at developing the database and techniques. This fiscal year we implemented in release 4 of the technical expertise required to design a concentrated on testing single-cell 805- standard version. We distribute the PC superconducting proton accelerator. MHz cavities. We have achieved version of these codes to users in the Earlier work had identified pion average and maximum values for peak accelerator community upon request. acceleration as a programmatic goal. surface electric fields of 30 MV/m and Changes in programmatic emphasis 50 MV/m, respectively. These are have given top priority to proton world class results, exceeding previ- acceleration. All of the previous design ously reported results at this frequency. and database work can be applied to the The values are consistent with the proton goal. design goals for the program, namely, a cavity average of 20 MV/m for the surface electric field. A next major step in the program is a test of a seven- cell, 805-MHz-cavity structure, complete with a stiffening structure for V-' i 4 S reducing microphonics, and a tuning fixture. The cavity (Fig. 2.11) was 3 designed in FY 1992 and has been ordered. The advantage of using superconduct- ing technology for accelerator struc- Fig. 2.I1. Prototype design drawing for a superconducting seven-cell cavity for ion accel- eration, emphasizing a mechanically rigid structure to reduce microphonics, field flatness tures is amplified as the accelerating upon ciiiilduwn to 5c'l, and high accelerating gradients. electric fields and the rf Qs (Q = rf stored energy/dissipated energy per cycle) are increased. Carefully controlled acid etching and cleaning of the niobium cells are essential if high fields are to be obtained. At Los Alamos the cells are acid-treated using facilities in MST division. The cells are then transported to AT-l's clean room for processing with ultraclean water. It is essential that ultraclean techniques are followed in the cleaning and handling of the cell. The cavity assemblies are sealed before they are removed from the clean room and subsequently inserted into the liquid helium cryostats (Fig. 2.12). Vacuum-oven treatment may be required to prevent the so-called "European Q disease.'" The treatment removes hydrogen from the niobium that can form a hydride during rela- tively long cool-down times. The Fig. 2.12. After clean-room assembly, an H05-MHz cavity is ready for testing in 2K helium superflitid liquid. (RB92 044 Oj) presence of the hydride can result in a Accelerator Technology Divixio 33 Technical Highlights • AT-1 • Accelerator Physics ami Special Projects degradation in the Q of the cell. The 3 GHz. We still need to verily the us lo seek a different solution. The iris "disease" has been cured by heat results at 805 MHz. region of the cell is a region of rela- treatment at SOOT. tively low-current density; it is, Achievements therefore, less sensitive to quenching. If rf Q values consistently equal to or We devised a fabrication procedure that greater than the design value of 5 x 109 We developed sufficient database and allowed the fabricator to weld the half- are to be obtained, the rf surface expertise to allow us to advance beyond cells at the equator, heat treat the resistance of the niobium must be low 3-GHz cavities and concentrate on 805- resultant single cell, and assemble the and the thermal conductivity high. A MHz-eavity processing and testing. seven-cell structure by welding the high thermal conductivity reduces the We have achieved approximately a individual cells together at the iris. As likelihood of the occurrence of a factor of 50% improvement in peak a test of this procedure, niobium quench at high electric/magnetic fields. surface field over the previously samples were welded together; some Annealing the niobium in a high- reported results from the worldwide samples were then titanium-getterecl temperature vacuum oven is effective database at 805 MHz (Fig. 2.13). The heat treated. Comparison of the in increasing the achieved values for Qs average value of the achieved electric residual resistance ratio at 4K (RRR) if the annealing also includes a process field, including an extrapolation to the values of the heat-treated and nonheat- that removes oxygen entrapped in the seven-cell cavity, exceeds the goal for treated samples showed that the niobium. This is done by titanium proton acceleration by -10%. damage to the RRR from e-beam gettering in a vacuum oven at ~1500uC. welding could be repaired by the Smaller 3-GHz cavities can be heat- During the fabrication of the seven-cell litanium-geltered heat treatment. We treated with ovens in the structures structure, niobium half-cells must be e- successfully tested the procedure using laboratory. An oven large i -nugh for a beam-wekled together. However, a 3-GHz cell. complete seven-cell structure is welding reduces the thermal conductiv- available to us through another division ity at the weld region. The cell is then This work, combined with additional of the Laboratory. prone to quenches from the supercon- <>nalyses of structural vibration and ducting state quenches that start at the mechanical stress, has allowed us to Under certain conditions high-pulse- equator weld, a region of relatively proceed with the next major program- povver (HPP) conditioning of a cell has high current density. The fabricator matic step, namely the procurement of improved the achievable elertric field can relieve this problem by heat- a seven-cell structure for tests in the in a below-par cell. HPP is attractive treating the entire seven-cell structure vertical cryostat. because it offers an opportunity to after welding. However, in our case, recondition an accelerating structure none of the potential fabricators had an A higher-capacity, roots-type, helium without removing it from the cryostat. oven large enough for the entire seven- vacuum pump was installed. This The testing reported here was done at cell structure. That situation required pump allowed us to achieve 2°K with 805-MHz cavities for the first time. 100 Also, the time to reach 2°K with 3-GHz 90 CERNA cavities was reduced from ~7 hours; an DESY • entire run can now be completed in a 80 LANL* few hours. CEBAF c? —* 70 SACUY O CORNELL • A high-pressure (1000 psi) ultrapure e B* WUPPERTAL D water rinse was installed this fiscal year > 60 B; KEK » in the structures laboratory's clean — 50 room (Fig. 2.14). The water rinse has CO ri So demonstrated its capability for remov- Fig. 2. IJ. A collection of representative peak surface electric fields obtained in \upercon- ducting cavities by various laboratories throughout the nurld. 34 Accelerator Technology Division Technical Highlights • AT-1 • Accelerator Physics and Special Projects The klystrons in the two COMARK transmitter modules are now operating at 805 MHz. The units previously operated at 500 MHz. We now have 10-kW cw capability and 100-kW pulsed capability at 805 MHz. These units can now be used to high-power- process cavities. Programmatic advantages accrue because we have demonstrated that cavities can be reconditioned in situ, thereby allowing us to return a faulty cavity to the line without having to return to room temperature for reconditioning. Waveguide components (variable coupler, window, and supports) for the high-power test and the seven-cell test have been designed and prototype- tested and are now undergoing final fabrication in preparation for the HPP test and the seven-cell cavity test (Fig. 2.15). In addition, the vertical cryostat for the test of the seven-cell structure has been delivered to the Laboratory. Fig. 2.14. A technician readies a cavity for rinsing with 1500 psi ultrapuie u ater Cavm cleaning and assembly takes place in a class 10 (static) clean room b\ lughh named The main program thrust is directed at personnel. Contamination control technology is also evaluated in this area using airborne completing the preparations for and the and liquidborne particle counters. test of the seven-cell structure in its vertical cryostat. Preparations include digging a pit in the high bay area of MPF-17 for the vertical cryostat. The program will also complete the HPP test of a single cell 805-MHz cavity. Fig. 2.15. As part of building accelerator systems, components such as vacuum windows, cavity couplers, drivelines. and probes need to be characterized and matched before the\ are installed on accelerator cavities. A T Division has extensive experience designing and building these components Shown is a VSWR measurement used for matching a coaxial elbow with a support stub. Accelerator Technology Division Technical Highlights mAT-l» Accelerator Physics and Special Projects Technical Memoranda 1. J. Billen, "New Root Finder tor SUPERF1SH on the PC," AT-1:93-301. September8, 1992. 2. R. Garnett, "Design of the SSC Linac," AT-1:91 -409, October 1, 1991. 3. E. Gray, "CEBAFTE Intercavity Coupling," AT-1:92-408, October 1, 1991. 4. E. R. Gray, "Cavity to Cavity Coupling Measurement," AT-1 :-91:4()6, October 1, 1991. 5. E. R. Gray, "Cavity Models, Cavity Coupling, and Geometric Coupling K," AT-1:91-407, October 1, 1991. 6. E. R. Gray, "Measured Beam Tube Coupling on PILAC Cavity Shape," AT-1:91 -459, October 6, 1991. 7. E. R. Gray, "Cavity to Cavity Coupling Induced Field Error," AT-1:91-421, Octobers, 1991. 8. E. R. Gray, "External Multicell Cavity Field Flattening," AT-1:92-7, January 9, 1992. 9. E. R. Gray, "Stainless Beam Tube Section Powar Loss," AT-1:92-18, January 15. 1992. 10. E. R. Gray "805 MHz RF Cavity High Power Processing," AT-1:92-19, January 16, 1992. 11. E. R. Gray, "Helium Displacement," AT-1:92-180, May 15, 1992. 12. E. R. Gray, "Cavity Frequency Change with Neck Extension," AT-1:92-252, August 2, 1992. 13. E. Gray, "A Traveling Wave Cavity Model," AT-1:91-460, November 6, 1991. 14. S. Nath, "Examples of Front-end ATW DTL's," AT-1:92-128, April 8, 1992. 15. G. Neuschaefer, "Examples 5 Tank 350 MHz APT DTL," AT-1:92-289. August 28, 1992. 16. G. Neuschaefer, "Experience with DTL Permanent Magnet Quadrupoles and Recommendations for a Space-Based Version of GTA," AT-1:92-! 31, April 13, 1992. 17. G. Neuschaefer, "805 MHz DTL LAMPF Upgrade," AT-1:92-245, August 9, 1992. 18. G. Neuschaefer, "ATW/APT 175 MHz RFQ's," AT-I:92-!')1, March 16, 1992. 19. G. Neuschaefer, "175 MHz APT/ATW RFQ Examples," AT-1:92-99. March 10, 1992. 20. G. Spalek, "Summary of Tuning Stresses and Loads for the 7 Cell Develop- mental Superconducting Cavity," AT-1:92-11, April 28, 1992. 36 Accelerator Technology Division Technical Highlights • AT-1 • Accelerator Physics and Special Projects 21. G. Spalek, "Power Requirements for 1 Cell and 7 Cell 805 MHz Superconduct- ing Cavities Being Developed at LANL," AT-1:91-410, October 1, 1991. 22. G. Spalek, "Estimate of Overpressure Protection of Developmental 7-Cell Cavity," AT-1:92-29, January 22, 1992. 23. T. Wangler and R. Stevens, "High-Transmission (HT) RFQ Designs for APT/ ATW," AT-l:92-0100, March 11, 1992. 24. T. Wangier, "Accelerating Structures for a Superconducting Proton Linac from a Beam Dynamics Point of View," AT-l:92-0107, March 16, 1992. 25. T. Wangler and L. Young, "RFQ Linear Accelerator for Pet Isotope Produc- tion," AT-1:92-324, September 22, 1992. 26. L. Young, "'Transient Analysis of PILAC Type Cavities used as Energy Booster on LAMPF," AT-!:92-265, July 29, 1992. Accelerator Technology Division 37 Technical Highlights * AT-3 • Magnetic Optics uittl Beam Diagnostics Inlroditcion 39 Background 39 Achievements 19 Optics Section 39 Beam Diagnostic Section 40 Mai>net Section 41 Mechanical Design, Fahiication, anil Assembly Section 42 Future Plans 42 References 42 Technical Notes 43 Technical Memoranda 44 Accelerator Tecluuiltigv Division Technical Highlights • AT-3 • Magnetic Optics and Beam Diagnostics Introduction New Techniques and frequently for the first-order beamline Code Development design. We ported the code to The AT-3 group charter is to "apply In a collaborative effort with J. van UNICOS, replacing the previous CTSS beam transport theory, state-of-the-art Zeits at the University of Maryland, we version for the Cray. We also com- diagnostic instrumentation, and developed computer codes to calculate pleted an impk mentation for SUN advanced magnet fabrication and higher order aberrations, now making it workstations, in which we wrote a measurement techniques to the design, possible to fully optimize high-order replacement for the PLOT 10 library, construction, and commissioning of aberration coefficients. These results eliminating the need for a Tektronix magnetic optic systems." To fulfill its have been checked against numerical terminal or emulator. This implemen- mission, the group maintains experi- integration and other codes developed tation uses the same TRACE3D code mental and construction facilities that at GAC that are not capable of optimi- used on VAX VMS systems, eliminat- include a diagnostic laboratory, which zation. Consequently, a significant ing the need to maintain separate SUN fabricates beam-diagnostic electronics; development, the concept of contoured- and VAX versions. a magnet-measurement laboratory, field telescopes, was developed. The which performs precision measure- principle is that the longitudinal We continued to develop the BEDLAM ments on a wide variety of electromag- dependence of each multipole is code, an experimental three-dimen- nets and permanent magnet assemblies; determined by the requirement that, sional, high-order space-charge code a mechanical design, fabrication, and while constrained to serve its primary that represents a beam by the moments assembly section; two rooms for laser function, it also does the least damage of its phase-space distribution. We development, used on the laser induced to the next higher order of aberration. tested the space-charge algorithm and neutralization diagnostics approach This technique generates designs in verified that the moment approach, as (LINDA) measurement system for the which the residual high-order aberra- expected, works very well in generating Ground Test Accelerator (GTA); and tions are reduced by one or two orders beams that are matched to high order in an area in the high bay, which as- of magnitude. Consequently, we have the presence of nonlinear forces. sembles beamlines. The group is also been able to apply this work to the responsible for managing a staff GTA and the neutral particle beam Beamline Designs and machine shop located in MPF-18 that space experiment (NPBSE). Project Support houses smail lathes, milling machines, We completed a new design of the grinders, sanders, drill presses, a bead We have studied various first-order GTA high-energy beam transport blaster, a bandsaw, a welding and achromatic 180° bend designs, includ- (HEBT) that includes an insertable brazing facility, and full vacuum leak ing space-charge effects. We devel- beam dump. Variable field permanent checking capabilities. oped the ACHRO code to help us magnet quadrupoles (PMQs) expand quickly generate and evaluate designs the beam in the beam-dump mode. Background for new requirements. This work has been applied to the GTA Optics We designed a 3.1 -m bend for GTA, Our group employs 33 full-time Experiments design. which consists of three five-cell, first- employees: 12 technicians, 20 staff order achromats. This design was members, and 1 group secretary (aided We refined our nonlinear beam studied extensively to determine effects by a part-time assistant). In addition, redistribution method and created of various magnet and beam errors and we have one industrial staff partner designs for several projects described to determine the aperture and steering from Grumman Aerospace Corporation below. Our designs take the beam requirements. (GAC) and two contract employees. leaving an accelerator and generate a distribution that is, to a good approxi- We determined that an energy-corrector Achievements mation, uniform over a large rectangu- cavity is required for GTA only if the lar region on the target. energy errors are beyond a certain Optics Section value, that a bunch rotator is not We verified some aspects of Parmila needed, and that we need a two- In PJ' 1992 the Optics Section contin- emittance growth predictions caused by frequency (425 and 850 MHz) momen- ued to develop those capabilities quadrupole roll errors in linacs. In this tum compaction system at the end of necessary to study and design work, we used P. Channell's mismatch- the bend. The system requirements beamlines and output optics systems emittance-growth theory to estimate were determined using a newly that must'meet very demanding emittance growth in terms of the roll- developed specialized code that requirements. We also created designs angle error. computed the fraction of beam on a and conducted studies that support a distant target, using an actual telescope variety of Lo.s Alamos projects. We continued to develop the design In estimate chromatic effects. TRACE3D code, which is used Accelerator Technology Division 39 Technical W/,i;/i//.i;/«.v • .47"-.* • Magnetic O/nics ami Hetim Diagnostics The measured beam behavior in Ihe in I-'Y IW2 we designed optics and another processing electronics module. intermediate matching section I IMS) o!' conducted studies for the Accelerator The complete beam-loss monitor GTA was found to he in good agree- Transmutation of Waste, pion linac. system provides two functions for ihe ment with our simulations; however, Intern....onal Fusion Materials Irradia- GTA. The primary function is to the existing heamline design coukl not tion Facility, NPBSE. CEED, and the provide a last ( < 10 ins) response provide a perfect match into the linac. Luggage Detection System. signal if a catastrophic accident should The nialching range of the IMS was occur in which the accelerator and insufficient to handle the somewhat Beam Diagnostics Section beamline components are placed in low brightness of the present beam. A peril because of direct beam impinge- redesign was proposed in which the The AT-3 Beam Diagnostics Team was ment. For particle beam energies PMQ sleerer magnets would he ichored involved with several programs in FY above 5 to K MeV, ihis interaction to lower their gradients. The proposed IW2. The majority of our efforts were would produce lower energy gammas, design is capable of nialching a much for the GTA program, bin we also which would be sensed by the system's wider range of beams exiling the radio- provided diagnostics support for the ioniz.alion chamber. If ihe gamma dose frequency quadrupole (RFQ). Advanced Free-Eleclron Laser (AFEL), rale is sufficiently high, a signal is sent Average Power Laser Experiment to a last protect system that, in turn, We created a specialized version of the (APLE), APLE Prototype Experiment shuts down the beam source. The ETRACEM code lor the dual-axis (APEX) Grumman Injector, and the second function of Ihe beam-loss radiographic hydrodynamic lesl Superconductor Super Collider pro- monitor system is to provide smaller (DAR1IT) project, adding features such grams. rates of beam loss, which in turn can as the ability to account lor random give the OTA commissioners more errors in Ihe magnets. The beam diagnostics team provided information about the beamline and GTA with permanent and characteriza- accelerator. We designed a beam-redistribution tion beam diagnostics for several beam system thai produces uniform or hollow experiments, including tests for the AT-3 also contributed to various distributions at the target for the Energy IMS, which matches Ihe beam from the electron beamlines attached to ihe free- Selective Neutron Irradiation Test RFQ to ihe inpul ol the drift tube linac electron laser (FEL). Both the AFEL (ESN1T) facility. We determined (DTL). The permanent beam diagnos- and APFIX facilities have received losses and effects oi duodecapole tics included within the IMS were three beam position measurement systems components in the oclupole magnels. mierostrip probes, a beam current that use capacitive probes and process- monitor, and a video beam profile. A ing electronics similar to those used for For the Accelerator Production of diagnostics platform or plate, for beam the GTA. Additionally, we began work Tritium (APT) project, we designed a characterization has a transverse on the APLE project, an electron linac/ beam-redistribution system thai emillance measurement (typically beamline tor high-average power FELs produces a large uniform beam al the described as a slii and collector emil- at Boeing in Seattle, by performing target and characterized the nominal lance scanner), a beam current monitor, beam tests on a flying-wire style of beam-inlensity distributions and their three more microslrip probes, a phase- charged-beam profile measurements operational variabilities resulting from spread measurement, and a longitudinal (FWBPM). beam jitter, beam-energy shifts emiilance measurement using a laser following rl-module failure, and beam- induced neutralization diagnostics We modified the design ol the proto- emittance shifts following acceleralor- approach (LINDA). Several papers type FWBPM system, originally quadrupole failures. Because the have been written describing these developed for use on ihe GTA, lo specifications include multiple targets. various measurements and the data improve ils performance anil to adapt it ihe HHBT designs used rf deflectors. acquired from these systems and were to measure beam-profiles lor the published al Ihe LINAC and PAC APLE/HPO high-current electron For ihe Los Alamos Neutron Scattering conferences this past year. Addition- accelerator. The signal's amplitude, Cenier II (LANSCF II) project, we ally, our team has written many AT-3 measured either directly off the wire, or identified and studied a candidate ring technical notes and several measure- indirectly from detectors located near design and dimensioned its apertures to ment operators manuals. the wire, is proportional In the beam accept I/.} ol the beam required al 800 that intercepts the wire. Hence MeV and 5 MW. Additionally, we One beam diagnostics system com- measuring the signal as the wire moves studied ihe ring design's injection pletely designed, prototype, and beam through Ihe beam will map out the chicane, bump-magnet scheme, and tested in limited quantities was the beam profile along Ihe axis perpendicu- extraction section. We also identified a beam-loss monitor system, which lar to the wire's motion. The APLE/ possible 2-('n.'V ring design. consists of an ion chamber and local I IPO FWBPM system has a pair of 35- preamplifier whose signal is cabled to dia. micron carbon wires mounted at 41) 'ralitr Icclinolttgv Division Technical Highlights • AT-3 • Magnetic Optics and Beam Diagnostics right angles to one another on a 17-cm video screen. We will conduct future wound with 850 turns of #30 copper diameter wheel. The two orthogonal studies to refine this measurement, to wire. The coils are placed in a wires allow both the X and Y beam determine the measurement resolution, Helmholtz configuration, and the profiles to be measured in the same and to determine which method of sample to be measured is rotated at the scan. A servo motor is used to acceler- signal detection yields the best results. center of the two coils by a small direct ate the wheel from rest to its peak Preliminary results indicate that the current (dc) motor. A 1000-pulse per speed in less than half a revolution, at signal-to-noise ratio is considerably revolution incremental encoder is which point the twn wires intercept the better on the charge collection ring, connected to the dc motor, and the beam and the whee! i\- decelerated back which if accurate would greatly coils' voltage is integrated and read in to rest before completing one full simplify the mechanism by eliminating every 20 encoder pulses by a Metrolab revolution. The electron beam that the need to make electrical contact with digital integrator. Data acquisition and intercepts the wire produces secondary the wires mounted on the rapidly control are through a GPIB interface to electrons that are detected either by moving wheel. a Macintosh Ilci running Labview. measuring the charge depletion current Magnet segments are mounted in a on the wires or by collecting the Finally, we delivered several toroids cubical holder that orients the sample's secondary electrons on a pair of (beamline devices used to measure x, y, or z axes parallel to the axis of positively biased collectors mounted up beam current) and a microstrip mea- rotation. The amplitude and phase of and down stream of the wires. The surement system to GAC. We have the signal, measured as the sample is goal of this system is to measure the extended this contract to include two rotated on its three axes, determines the profile of a -1 ms-long, ~ 1 mm- more microstrip systems which will be magnetic moment in the plane perpen- diameter high-current electron beam used with a small test stand for experi- dicular to the axis of rotation. These with a resolution of 100 mm or better ments with injector automation results can then be used to calculate the without over heating and breaking the experiments. x, y, and z components of the magnetic fine carbon wire. For the wires to moment, the overall magnitude (M), survive in the APLE/HPO beam, the Magnet Section and angular deviation of M from the wire must be capable of sweeping desired orientation (DQ). The uncer- through the beam at a speed of 20 m/s Magnet Measurement tainty in the absolute measurement of M is estimated to be ± 1 %, and the or better. Achieving these speeds in In July 1992, we completed our final uncertainty of determining the absolute just half a revolution does not leave cryo mapping of the permanent magnet DQ is estimated to be ± 0.5°. The enough time for the wheel velocity to DTL quads for the GTA. Over 200 relative uncertainties of M and DQ are stabilize before the wires sweep cryo maps were taken to measure the much better, + 0.05% and ± 0.25°, through the beam. To overcome this gradient length (GL) product vs respectively. problem, the wheel velocity is recorded temperature (T) dependence of the 140 as the wires move through the beam, PMQs need for the DTL. This effort allowing the data to be corrected for occurred over a year and a half as the Magnet Design and Fabrication any variations in velocity. magnets were received from the Four variable field permanent magnet vendor. The cryo mapper specifically quadrupole (VFPMQ) doublets and one The APLE/HPO FWBPM system has designed for this task worked remark- singlet were designed and fabricated by been tested at the APEX electron ably well; once operational, it experi- AT-3 for use on the AFEL. The basic accelerator using a high-intensity low- enced very little down time. It mea- design of the AFEL VFPMQ is similar duty beam of - 40-MeV electrons. sured the GL vs T of the cryo quads to the magnets built for the GTA IMS, However the typical macropulse length from room temperature to 20K and which are patterned after the concep- of the APEX beam is too short (< 20 back to room temperature with an tual design proposed by K. Halbach.1 ms) for the moving wires to intercept. absolute uncertainty of ± 0.5% in a The magnetic design criteria for the Instead the wires were moved slowly cycle time of approximately 3 hours per magnets were a clear bore diameter of through the beam to map out a beam magnet. 26.2 mm, a quadrupole gradien' that profile averaged over many can be continuously varied from 0 to 60 macropulses. Preliminary results A Rotating Sample Magnetic Moment T/m, minimal allowed harmonics, and indicate that the signal strength Mapper (RSM3) was built by the AT-3 35-mm-long pole tips. Two key measured from the wires and charge magnet lab to measure the direction and mechanical design features of these collectors agrees with the calculated magnitude of the magnetic moment of magnets were that the doublets were signal strength; and a preliminary beam permanent magnet material samples. made by mounting two VFPMQs I cm profile measurement also indicates that The design for the RSM3 is patterned apart in the same housing and thai the the profile measured with this system after a similar device built by Lawrence polarity of each VFPMQ could be had roughly the same shape and width Berkeley Laboratory.': It consists of a easily reversed without disassembling as the profile observed on a nearby pair of 45-cm diameter coils each the unit. The mechanical design was Accelerator Technology Division 41 Technical Highlights • AT-3 • Magnetic Optics and Beam Diagnostics found to work well and the magnetic liaison work, fabrication, assembly, References measurements were in excellent installation, machining, welding, and agreement with the calculated results. vacuum leak certification. This service 1. D. Nelson, P. Barale, M. Green, The magnets were installed on the supports other sections within AT-3, AT and D. Van Dyke, IEEL Tauisuaions AFEL and have been in continual use Division, other accelerator laboratories, on Magnetics, 24, No. 2, 1098 (1988). since June 1992. Grumman Aerospace Corporation, the U. S. Navy, Boeing Space and Science 2. D. Nelson, P. Barale, M. Green, Additional subroutines tor three- Division and the GTA program. and D. Van Dyke, 9th International dimensional modeling of large-bore Conference on Magnet Technology, optics elements were incorporated in Some of the components that this p 735. MARYL1E and TLIE, the two high- section has provided are: beamline order optics codes being developed in diagnostics, full sections of beamlines, 3. K. Halbach, Nuclear Instruments collaboration with the University of experimental beamlines, beamline and Methods 206, 353-354 (1983). Maryland. These new subroutines support structures, resistive dipole and allow us to compute error effects, quadrupole magnets, harps, vacuum including "hidden" multipoles in boxes, steering magnets, Lambertson- permanent magnet quadrupoles, i.e., type correction dipoles and quadrupole field components arising from axial magnets, variable field permanent components of magnetization. These magnet quadrupoles, and variable field field components integrate to zero and permanent magnet dipoles. are not seen in integral field measure- ments, but can affect higher-order Future Plans optics. Our future plans are to complete the A preliminary design for a prototype beam diagnostics for the GTA accelera- ferrite kicker magnet module for use in tor and begin the beam diagnostic work proton storage rings was completed in for the GTA bend and telescope. We FY 1992. The design incorporates will continue to build beam diagnostics various features to minimize the rise for APLE, and increase our diagnostics time, including use of a parallel support for SSC. speedup capacitor and a series saturable inductor. We will increase our magnet design, building, and mapping support for the The cylindrical current-sheet magnet SSC. We also anticipate building concept was extended to short iron-free magnet mapping devices for the SSC. quadrupoles. These magnets are designed to produce a magnetic field The AT-3 optics section will support the with nearly perfect sin 2F symmetry bend and telescope design for GTA, about the beam axis; the residual support storage ring design for integral error multipoles due to finite- LANSCE II, and support the ABC turn-number effects are zeroed out by projects with optics design for creating small shifts in the conductor positions uniform beam illumination target specified by a computer algorithm design, and increase our support for the developed in 1992. Precise conductor SSC. placement is achieved by fixing the superconducting wires in grooves that are machined in a particular pattern in a cylindrical surface by a numerically controlled milling machine. Mechanical Design, Fabrication, and Assembly Section The mechanical design, fabrication and assembly section provides design, quality control of design packages. 42 Accelerator Technology Division Technical Highlights • AT-3 • Magnetic Optics and Beam Diagnostics Technical Notes The following AT-3 Technical Notes were written during the report period. 1. R. E. Shafer, "Effect of Alignment Errors in the GTA-24 180 Degree Bend," Los Alamos National Laboratory Technical Note AT-3.91-16, October 1991. 2. B. Blind, "Beamline Configuration for Simulation Delivery of p+ and p- to PILAC," Los Alamos National Laboratory Technical Note AT-3:91-17, October 1991. 3. B. Blind, "A Beam Delivery System for the ATWE," Los Alamos National Laboratory Technical Note AT-3:91-18, October 1991. 4. R. Connolly, "The Optics Design for a Spectrometer to Measure the Energy Distribution of 10-100-MeV Proton Beams," Los Alamos National Laboratory Technical Note AT-3:91-19, November 1991. 5. C. R. Rose and D. Wells, "Owner's Manual, 'Position Detector'," Los Alamos National Laboratory Technical Note AT-3:91-20, November 1991. 6. P. L. Walstrom, "Magnetic Fields from Distribution of Dipoles on Cylindrical Surfaces," Los Alamos National Laboratory Technical Note AT-3:91-21, November 1991. 7. B. Blind, "A Choice of Point-to-Parallel Focusing Modules," Los Alamos National Laboratory Technical Note AT-3:92-l, February 1992. 8. R. H. Kraus, Jr., "Permanent-Magnet Material Applications in Particle Accelera- tors," Los Alamos National Laboratory Technical Note AT-3:92-2, February 1992. 9. J. D. Gilpatrick, "Microstrip Measurement Algorithms," Los Alamos National Laboratory Technical Note AT-3:92-3, February 1992. 10. P. L. Walstrom, "Temperature Rise due to Gorter-Mellink Mutual Friction in the Pilac Horizontal Cryostat," Los Alamos National Laboratory Technical Note AT-3:92-5, March 1992. 11. B. Blind, "Beam-Redistribution System for ESNIT," Los Alamos National Laboratory Technical Note AT-3:92-6, May 1992. 12. B. Blind, "Useful Formulas for Cylindrical Resonators in TM110 Deflecting Mode,' Los Alamos National Laboratory Technical Note AT-3:92-7, July 1992. 13. J. D. Gilpatrick, "Double Balance Mixer Operation used as Phase Synchronous Detector as Applied to Beam Position and Intensity Measure," Los Alamos National Laboratory Technical Note AT-3.92-8, July 1992. 14. C. R. Rose, "Operator's Guide 425/850 MHz Down Converter Version 3.0," Los Alamos National Laboratory Technical Note AT-3.92-9, September 1992. Accelerator Technology Division 43 Technical Highlights • AT-3 • Magnetic Optics and Beam Diagnostics Technical Memoranda The following AT-3 Technical Memos were written during the report period. 1. E. A. Wadlinger and W. P. Lysenko, "Maximum Energy Jitter from the 24-MeV C.TA Linac." AT-3:9l-573, October 3, 1991. 2. W. P. Lysenko. "TRACE3D on Sun Workstations," AT-3:91-599, October 15, 1991. 3. W. P. Lysenko. D. P. Rusthoi, and E. A. Wadlinger, "GTA Bend Aperture Requirements," AT-3:91-601, October 16, 1991. 4. W. P. Lysenko, •'Experiment 3 Physics Design Status," AT-3:91-605, October 16, 1991. 5. W. P. Lysenko, "Status of Linac Quadrupole-Roll-Error Study," AT-1:91 -620, October 22. 1991. 6. W. P. Lysenko, "Update on TRACE3D for Sun Workstations." AT-3:91-665, November 19. 1991. 7. E. A. Wadlinger, D. P. Rusthoi, and W. P. Lysenko, "GTA Bend Aperture Requirements for the 3.1-m Bend Experiment," AT-3;92-41, January 24, 1992. 8. W. P. Lysenko, "HEBT for 3.1-m Bend Experiment," AT-3:92-145, March 17. 1992. 9. W. P. Lysenko. "HEBT Steering and Matching Range," AT-3:92-386, August 11, 1W2. 10. D. P. Rusthoi. "3.9-m Bend (Lattice #12): Error Studies with Acceptance Beam." AT-3:91-588. October 8. 1991. 11. D. P. Rusthoi. "3.9-m Bend (Lattice #12): Quadrupole Field Error Studies," AT-3:91-597. October II. 1991. 12. D. P. Rusthoi, "GTA Bend Aperture Requirements," AT-3:91-601, October 16. 1991. 13. D. P. Rusthoi. "3.9-m Bend (Lattice #12): R-Matrix Elements for Steering Studies." AT-3:91 -631. October 28, 1991. 14. D. P. Rusthoi, "Study of Coherent Achromats with Space Charge," AT-3:91 -644. November 5. 1991. 15. D. P. Rusthoi. "3.9-m Bend (Lattice #12): Steering Algorith Application," AT-3:91-681. November 27. 1991. 16. D. P. Rusthoi. "3.1-m Bend (Lattice #13): New Lattice Parameters," AT-3:91-70S. December 16. 1991. 17. D. P. Rusthoi. "3.1-m Bend (Lattice #13): Second Order Analysis." AT-3:91 -72 I. December 23,1991. 44 Accelerator Technology Division Technical Hishligltts • AT-3 • Magnetic Optics and Benin Diagnostics 18. D. P. Rusthoi, "3.1-m Bend (Lattice #13): Quadrupole Field Error Study," AT- 3:92-003, January 6, 1992. 19. D. P. Rusthoi, "3.1-m Bend (Lattice #13): Space Charge Study," AT-3:92-O17, January 13, 1992. 20. D. P. Rusthoi, "3.1-m Bend (Lattice #13): Magnet Skew Study," AT-3.92-022, January 15, 1992. 21. D. P. Rusthoi, "3.1-m Bend (Lattice #13): Error Studies with Acceptance Beam," AT-3:92-024, January 16, 1992. 22. D. P. Rusthoi, "3.1-m Bend (Lattice #13): Dispersion & R-Matrix Data," AT-3:92-032, January 22, 1992. 23. D. P. Rusthoi, "3.1-m Bend (Lattice #13): Steering Error Calculations," AT-3:92-040, January 24, 1992. 24. D. P. Rusthoi, "GTA Bend Aperture Requirement for the 3.1-m Bend," AT-3-.92-041, January 24, 1992. 25. D. P. Rusthoi, "3.1-m Bend (Lattice #13): Steering Algorith Application," AT-3:92-059. February 3, 1992. 26. D. P. Rusthoi, "GTA IMS: Emittance Measurements/Predictions Compared," AT-3.-92-113, February 27, 1992. 27. D. P. Rusthoi, "GTA IMS: Emittance Measurements/Predictions Compared & Model Corrected," AT-3:92-123, March 4, 1992. 28. D. P. Rusthoi, "3.1-m Bend (Lattice #13): Effect of Higher Dipole Tolerances ...," AT-3:92-138, March 13, 1992. 29. D. P. Rusthoi, "GTA IMS: VFQ Settings for Rounder Beams at ES5," AT-3:92-179, April 14, 1992. 30. D. P. Rusthoi, "DARHT: Match and FODO Lattice," AT-3.92-214, May 12, 1992. Accelerator Technology Division 45 Technical Highlights • AT-4 • Accelerator Design and Engineering Introduction 47 Achievements 48 GTA 48 Design of the Accelerator for Production of Tritium (APT) and Transmutation of Waste (ATW) ". 5/ Seven-Cell Superconducting Cavity and Superconducting Cavity Chains 54 Support of Others 57 Environment, Safety, and Health (ES&H) 59 References 59 Technical Memoranda 59 At i clerulor Tcclmoltigy Division Technical Highlights • AT-4 • Accelerator Design ami Engineering Introduction sible for designing cryogenic accelera- quirements for CAD systems as well as tor components as well as for develop- for drawings. Responsibilities also AT-4 represents one of the strongest ing and implementing the engineering include meeting the Department of mechanical engineering organizations methodology necessary to the success Energy (DOE) program requirement for at the Los Alamos National Laboratory of our projects. Methodology includes three levels for drawing archi al as (LAND, combining the individual physics and engineering criteria defini- well as for adhering to a drawing sys- strengths found in other Laboratory tion documents, a design review pro- tem. In addition, DOE programs are mechanical engineering organizations cess, value engineering, and training beginning to apply QA procedures to and focusing them on the design of new engineers. the design process by requiring design radio-frequency (if) accelerators. The reviews, design notes, and specifica- group is currently composed of five Our mechanical drafting section pro- tions documentation. Consequently, sections: analysis, mechanical engi- duces machine drawings that vary in this section is responsible for imple- neering, mechanical drafting, test engi- scope from sketches to manufacturing menting these QA functions for the neering, and drawing production and drawings. Manufacturing drawings are other sections in the group as required. quality assurance (QA). The central- produced using geometric tolerancing ization of these sections has allowed us to ANSI Y14.5 standards and incorpo- In FY 1992, we have witnessed several to build a stronger capability in AT rate drawing system requirements successes in project related activities Division. based on DoD-D-1000 standards. The within the group. The Ground Test drafting section incorporates a formal Accelerator (GTA) has been commis- The engineering analysis section has drawing checking procedure as well as sioned up to and including the first drift developed and supported a sophisti- a formalized drawing change proce- tube linac (DTL) module. This accel- cated analysis capability incorporating dure. This section uses a CAD system erator, engineered and constructed by PATRAN/ABACUS software and with S:G stand-alone work stations, AT-4, has been immensely successful; Silicon Graphics engineering work which operate in a secure environment, both the RFQ and the DTL have oper- stations. This system allows us to and ICEMDDN CAD software. In ated flawlessly. The intertank match- model both the structural as well as the addition, the mechanical drafting sec- ing section (IMS), which required the rf thermal response of very complex tion manages the electronic archival of couplers be redesigned and the steering geometries as well as the vibrational drawings. magnets be modified to account for a response of systems. The analysis broader operating requirement, has also section is also responsible for develop- The test engineering section is respon- been a success, particularly because it ing computer aided engineering (CAE) sible for assembling and testing hard- is such a highly complex piece of hard- techniques for accelerator development. ware designed by the engineering and ware. AT-4 has also successfully pro- We are currently using these techniques design sections; designing assembly gressed toward a preliminary design of to build cold models of complex rf and testing fixtures; and assembling the GTA optics system and is begin- structures using a stereo-lithography complete accelerator cavities including ning the conceptual engineering design technique. The basic goal of the tuners, magnets, positioning devices, rf of an upgrade to the Proton Storage project is to build an actual cold model couplers, diagnostics, and cooling Ring facility, which could represent a of the part in a few hours based on an manifolds. Typical testing involves major engineering project in the next electronic model of the part (computer pressure and flow testing of accelerator few years. The group has continued to aided design [CAD] solids representa- cavities, vacuum and cryogenic testing provide engineering support to other tion) using i stereo-lithography tech- of components, load, positioning, and groups and divisions associated with nique combined with a copper deposi- repeatability testing of magnet accelerator work. We participated in tion process. This electronic model positioners, i'.nd testing of rf tuners. the superconducting RFQ design, an would also be coupled with our thermal This section operates three cryogenic accelerator for the Federal Aviation and structural analysis software to lest facilities capable of operating at Administration for baggage inspec- allow us to analyze the part from a 20K with refrigeration capacities up to tions, and supported the beamline com- common data base. 750 W and operates a vacuum labora- ponents design for the Clinton P. tory that incorporates ultra-high Anderson Meson Physics Facility Our mechanical engineering section is vacuum test apparatus. (LAMPF) accelerator. We are a matur- responsible for the mechanical design ing organization who has developed the key elements to support a successful of accelerator components, including Our drawing archival and QA section is engineering organization. engineering accelerator cavities, mag- responsible for drawing production, nets, couplers, diagnostics and beam reproduction, hard copy archival, and line components such as vacuum ves- QA functions in the group. This sec- sels, support structures, and cooling tion also operates the drawing security systems. This section is also respon- vault and maintains the security re- Accelerator Technology Division 47 Technical Highlights • AT-4 • Accelerator Design and Engineering Achievements All components are available except the be operating as expected through the remaining drift-tubes for modules #8- high-power conditioning phase. GTA 10. which are being completed at Westinghouse Hanford Company. Dur- Figure 4.1 shows module #1 completely DTL Assembly and Testing ing FY 1993, final assembly and testing assembled before installation into the The drift tube linae (DTL) comprises of the remaining DTL modules is DTL vacuum vessel for beam experi- the major portion of the 24-MeV GTA. planned for eventual installation on the ment 2A. Module #1 has been opera- It consists of 10, 1-meter long. 850 GTA beamlinc. tional on the GTA beamline for beam MHz cavities containing a total of 130 characterization experiments since early drift-tubes. It resides immediately Acceptance testing of each module is an September 1992, This module has been downstream of the Intertank Matching extensive set of tests consisting of (1) operating as expected with no apparent Sections (IMS) on the GTA beatnline. room temperature alignment of the drift- problems. Figure 4.2 shows 8 of the 10 tubes, (2) room temperature resonant DTL modules in various stages of Four DTL modules have been com- frequency tuning of the cavity, (3) How assembly to indicate the complexity of pleted through high power rf accep- orifieing and pressure/leak testing, (4) the assembly process as each module is tance testing at operating temperature low power cryogenic testing to evaluate built up io be fully operational. (20K). One additional module is com- changes in drift-tube alignment and pletely assembled and in the process of resonant frequency from room tempera- Waveguide Basement Floor Analysis testing. The remaining five modules ture, and (5) high-power rf conditioning and Installation are in various stages of assembly. of the cavity prior to installation on the Upon completion of experiment 2A, we bcamline. The DTL modules appear to will move the GTA experiment from the tunnel's northeast corner to the south side of the tunnel and position it directly over the waveguide basement. Conse- quently, we significantly modified the existing tunnel floor dynamic-input spectrum. Because the accelerator will now be supported on a suspended strongback, we are confronted with additional design challenges. Initially, the DTL accelerator was designed for a dynamic-input spectrum in the previous, more benign, stable location. In its new location, it will be exposed to more background lateral vibration sources (e.g., pumps and compressors) than the original, conventional support structure was designed to accommodate. As a result, the Moor was laterally isolated from the north wall, but still is able to support vertical loads. Fig. 4.1. I ulh iiwi mhleil ilnji tube limn 11)11.) module Ml f-ig. 4.2. Assembly sltiges of drift lube linac (DTL) niudiilvs (Juanitu Romero, AT-4). Accelerator technology Division Technical Highlights • AT-4 • Accelerator Design and Engineering AT-4 and MEE-13 had initially devel- growth. These simulation efforts identi- oped to validate the resultant design. oped a finite element model of the DTL fied the level of vibration isolation re- Figure 4.3 shows one of the three assembly from the base of the module quired, such that the resultant inputs to waveguide floor modules before instal- support pedestal to and including the the base of the support pedestal are at or lation into the GTA tunnel. The numer- drift tube mounted into the DTL mod- below the original design environment. ous cutouts shown provide access for if ule. Following vibrational analysis, we In addition, a modal survey was done waveguide and utility feedthroughs. found this model's drift tube displace- using DTL module #4 to verify the The three floor sections were delivered ments were very small and could there- finite element model results. These in August and have been installed into fore be neglected. MEE-13 measured results indicated the strongback needed the GTA tunnel. The numerous cutouts the dynamic response of the floor to redistribute loads while maintaining shown provide access for rf waveguide around the waveguide basement in 1992 me required alignment during accelera- and utility feedthroughs. The three floor and updated the dynamic model to in- tor operation. The structure had to be sections were delivered in August 1992 clude the new strongback. It was then stiff enough to preclude deflections and have been installed in the GTA found that the vibrations at the interface during operation at high vacuum after tunnel. to the basement's north wall caused alignment at atmospheric pressure. larger drift tube displacements than the During high-vacuum operations, the previous model had indicated. Beam 6000 lb vertical up load at each of the dynamic analyses showed that these 10 DTL pedestals must be balanced by drift tube displacements produced the 60,000 1b vertical load distributed enough of a steering error to give an over the vacuum vessel feet. A struc- unacceptable apparent emittance tural finite element model was devel- Fig. 4.3. Ground test accelerator I GTA) waveguide basement floor module. Accelerator Technology Division 49 Technical Hif-hlif-lns • AT-4 • Accelerator Pesif-n and Ennineeriii Optics Design ible item and was designed as a ing launch. Consequently, this effort The GTA optics design went through pseudomonocoque or truss structure. involved making layouts and perform- several changes again in FY 1992, This design addressed and met its ing preliminary dynamic and thermal including conceptual designing, cost- goals: an efficient lightweight structure analyses. ing, and scheduling. At ihe beginning to cany flight and launch loads, main- of the fiscal year, efforts were directed tain the precise magnet alignment re- After the cost estimates and tradeoff toward designing and building a "space quirements, maintain the particle beam analysis were completed, we decided qualifiable" optics system, meaning the axis in line with the structural axis to the GTA experiment would be moved hardware would be designed for a reduce high-interface stresses from to the south wall where it would face space mission, but not tested. How- eccentric load paths, provide mainte- east. Four other optics systems were ever, if funding were to become avail- nance and accessibility to the beam investigated to help reduce the overall able, the system could be tested and diagnostics and magnets, and have a cost and schedule. The first was an flown. Consequently, we created a reasonable assembly and commission- 8.5-MeV ground '"straight shooter," conceptual design of the system and ing plan. which would follow after DTL module built preliminary thermal, structural, #5 was considered, eliminating the cost and dynamic finite element models. The design change resulted in us split- of installing the five remaining DTL The thermal model determines both ting die optics program into two paths. modules mid delaying the bend design spatial and time-varying temperature The first direction was to design the 24- and fabrication until a later date. The profiles of the space structures and their MeV ground telescope and eliminate telescope would be designed so it magnets, including the on-orbit envi- the bend entirely, which would leave could be upgraded to a 24-MeV con- ronmental heat fluxes such as solar, the GTA accelerator on the north side figuration. The second optic system albedo, and the earth's infrared. Dy- of the tunnel facing west. We com- considered was to design both an 8.5- namic and structural models were built pleted a work breakdown schedule and MeV bend and telescope and install using beam and shell elements, respec- cost estimate to determine if the hard- them after DTL module #5, with both tively, to interface with the existing ware and labor savings would offset the assemblies potentially upgradable to Titan III model McDonnell Douglas utility and facility costs associated with 24 MeV. The third design would be an established for the neutral particle leaving the experiment in its present S.5-MeV space optics system, which beam space experiment (NPBSE) in location. The second direction was to would compete with FOX for funds set 1991. These models enable parameters go back to a space design to support the aside for a space experiment. The such as mounting schemes to be opti- far-field optics experiment (FOX) fourth system involved designing a 24- mi/.ed for minimized weight. Much of headed by Grumman with team mem- MeV ground system that would be the required interface data such as bers from McDonnell Douglas and installed after the initial DTL experi- geometric relationships to other space- LANL. The FOX is a 5-MeV "straight ment when funds became available. craft hardware, internal heat sources shooter" with a single joint enabling the After evaluating design configurations, and weights, and launch and space telescope to be folded for storing dur- cost estimates, future plans, and sched- environment dynamic loads were de- veloped from past reports (e.g.. NPBSE. NPBIE). WATER MANIFOLDING (REQUIRED FO? -OI AGNOSTICS ACTIVE STEERINGI During the fiscal year the design focus changed to match the actual program funding. The change eliminated the term "space qualifiable"" from the hard- ware description and replaced it with "spai.-'j cognizant." meaning the optics system would look as if it could go into space, hut there would be no analysis to support the design. The high-energy beam transport (HEBT). eyepiece, and steerer would be designed as ground experimental hardware only and would not be required to be space compatible. The change eliminated the term "space IEB1 INTERFACE • BEAMTUBE TO FLANGE. cognizant" from describing the tele- MOMENTUM COMPACTOR scope. The bend, shown in Fig. 4.4. CAVITIES was still to remain as a space compat- lit;. 4.4. (irotind lest accelerator {(HA) optics bend 50 Accelerator Technology Division Technical Highlights • AT-4 • Accelerator Design ami Engineering ule impacts, the fourth choice was The beam is injected into a side- elevated energies will produce suffi- chosen as the program direction. coupled linac structure similar to cient neutrons above a few MeV to LAMPF where the beam is accelerated significantly shorten the lives of rare Once the program focused on the 24- to 1 GeV before it is directed to the earth cobalt-magnet materials. Using MeV ground optics system, we com- tritium production targets. electromagnetic quadrupoles in the pleted a conceptual design of the bend. DTL, which dictate the minimum size After reviewing the available tunnel While this study involves the concept for the DTL drift tubes, coupled with layout, vibrationally unstable floors, of using a machine to produce tritium, the need for continuous-duty rf sources, and the logistics of multiple set-ups, an with minor adjustments in output en- resulted in our choosing the 350 MHz active alignment scheme using theodo- ergy and current, the machine can be for the front end of APT. lites did not seem feasible. Therefore, used to treat radioactive waste (i.e.. the design presently evolving uses tight Accelerator for Transmutation of Following the funnel at 20 MeV, we tolerances, a quadrupole assembly Waste [ATW1 or Accelerator Based identified a more difficult problem: the fixture with taut-wire alignment appa- Conversion [ABC]) or act as a neutron need for low-energy, large-bore, high- ratus, and a coordinated assembly plan factory of unprecedented flux. It is, frequency (700-MHz) structure to ac- to ensure the bend magnets are properly therefore, a design with wide ranging celerate the beam to its final energy. It aligned. applications. The basic design, how- was evident that a standard coupled ever, is water-cooled and conventional cavity linac (CCL) would function well, Design of the Accelerator for in nature as compared with more ex- but only at 80 or 100 MeV and above. Production of Tritium (APT) and otic superconducting approaches. To bridge the gap between 20 and 10l> Transmutation of Waste (ATW) MeV, we needed an entirely new struc- Mechanical Design ture to avoid the structural, cooling, and Since the conception of LAMPF, the One of the key decisions we made operational problems of a very low- greatest challenge for the linac designer early in this study was to use electro- energy CCL. We developed the has been to engineer high-current, magnetic quadrupoles in the DTL to BCDTL for this purpose (Fig. 4.5). It continuous-duty machines: several of resist radiation effects. Even small consists of short accelerating modules, our present studies involve such ma- losses in a 200-mA proton beam at seven beta-lambda in length, which the chines. During 1992. AT-4 led the engineering design, under a DOE study Ein = 20.0 MeV Eout = 20.8 MeV contract, for a 200-mA, 1000-MeV. cw, water-cooled machine called the Accel- erator for Production of Tritium (APT). This work has required that we develop new cavity structures, and solve special cooling and maintenance problems, setting the stage for other machines of a similar nature. A conceptual design for the APT accel- erator has been in progress during FY ©25.4cm— 1992. This accelerator consists of a pair of 100-mA proton sources feeding two RFQ's that operate at a resonant frequency of 350 MHz raising the beam energy to 7 MeV. The beam is then delivered to DTLs designed for 350- MHz transmission, further raising the energy to 20 MeV before the two beams are funneled into a single 200- mA beam with a microstructure fre- 0 5 10 cm quency of 700 MHz. At this point, a new accelerating structure is evoked, called a bridge coupled DTL (BCDTL). to carry the beam to 100 MeV. At 100 . Multicell Bridge Coupler MeV the beam power is 20-MW cw and must be handled with extreme care. Fig. 4.5. BCDTL 7()()-MHz accelerating tank at 20 MeV. Accelerator Technology Division 51 Technical Highlights • AT-4 • Accelerator Design and Engineering beam dynamicisls find give excellent ing from the inherent low-shunt imped- beam transport results. We placed ance of a CCL structure below 100 quadrupole doublet focusing magnets MeV. Figure 4.6 shows a four-tank for strong focusing between modules at assembly of a BCDTL module. rf window ion pump (4) short intervals. Each of the BCDTL 1201/s 94 lbs accelerator tanks holds six drift tubes, Once the beam energy has been raised unique in that they do not carry quads. to 100 MeV, a conventional pi-mode In addition, the drift tubes have ex- CCL is the best structure to use. The tremely large bores considering ine shunt impedance is now higher than u high frequency at which they must BCDTL and the fabrication and cooling operate. Because there are no quads in problems are greatly diminished. A the drift tubes, alignment tolerances can precedent also exists in LAMPF for be more lenient (± 0.5 mm). Conse- CCL structures fabricated at this entry quently, the drift tubes can be "hard energy, although at 700 MHz, the APT socketed" for good rf seals, which are cavities are 15% larger than LAMPF necessary for cw operation. The aper- and marginally difficult to braze. This ture ranges from 4 cm in diameter at 20 factor is another reason why the choice MeV to 5 cm at 100 MeV. It is desir- of 350 and 700 MHz was made for able to achieve a high-aperture ratio of APT. Below 700 MHz, a CCL be- bore diameter to beam diameter to comes difficult to build because of its prevent beam losses and radioactivation increased size and bulk. The frequency by the beam. The BCDTL effectively choice that was selected is ideal from overcomes the problems caused with an an engineering, cavity structures and equivalent CCL at the same low ener- fabrication standpoint. gies by eliminating the close-spaced rf surfaces, multipaeloring, and other The 100-MeV CCL module, shown in operational difficulties. Also elimi- Fig. 4.7 represents over 300 such mod- nated are cooling and fabricating prob- ules in the CCL, which compose 90% Fig. 4.6. Bridge coupled drift tube linac lems, and inefficient rf operation result- of the bulk and cosl of the APT linac. (BCDTL) module at 20 MeV. Fig. 4.7 CCL 3 5 bate lambda al 10173 MiV 7 tola lambda all 0?SSM»V 52 Accelerator Technology Division Technical Highlights • AT-4' Accelerator Design anil Engineering • 7 (IX accelerating tank (4) -em quadrupole doublet (4) -multicell bridge coupler (3) OWG meter Accelerator Technology Division 53 Technical Highlights • AT-4 • Accelerator Design and Engineering This structure is designed around a tirely and taken to the lab for total as a complete unit for major repairs. single halt-cell concept in which half overhaul, perhaps in a hot cell. A re- the coupling cell and half the accelerat- placement unit, prealigned in the lab The general APT design described ing cell are machined into the same and completely checked out. could then above is applicable to any proposal for forging. This is a departure from the be slid onto the rails providing pre- a water-cooled, tunneled machine in technique used at LAMPF in which the determined alignment with the as- the 300- to 900-MHz range that accel- coupling cells were brazed as separate installed hardware. erates protons to energies of 1 to 2 assemblies. However, by splitting the GeV, operates at beam currents up to accelerating cells along the septum The entire APT is designed to be 350 mA, and functions in a cw mode. midplane. it is now possible to machine modular in that each klystron amplifier This APT study has been a great engi- adequate cooling channels to accom- drives a segment of the accelerator neering challenge, has placed us in a modate c\v operation of the structure using from 600 kW to 1.25 MW of position to deal with similar machines because septum rf heating is of primary total power. Each accelerator module for radioactive waste disposal, and has concern in a cw CCL. Along with the is mounted onto a rail system complete shown potential lor future applications, septum cooling channels, an internal with a self-contained vacuum system, channel is also machined around the water-cooling manifold, focusing sys- Seven-Cell Superconducting Cavity coupling cell periphery. A cross section tem, diagnostics and essential instru- and Superconducting Cavity Chains of the resulting septum cooling chan- mentation. It is prechecked, aligned, nels is shown in Fig. 4.8. The entire and rf conditioned offline and then One of the most advanced supercon- cooling system for a seven beta-lambda transported to the machine tunnel ducting cavity prototypes was designed long structure consists of longitudinal where it is installed on prealigned kine- and released for fabrication during gun-bored cooling channels around the matic mounts. This modular approach FY 1992 after a collaborative effort periphery of the tank assembly distrib- allows the machine to be maintained between AT-4 and AT-1. The proto- uted in pairs, with each pair feeding a either in sections, offline, or removed type consists of seven cells of high- single septum and coupling cell. The flow is mass balanced and confined to counterflow, which results in a uniform temperature distribution along the length of the lank. Development of this cooling scheme along with the BCDTL constitute two of the major engineering breakthroughs in the APT linac design. septum cooling A third significant design development is based on the potential need to per- form maintenance on beamline compo- nents under radioactive conditions, which demands quick or even remote servicing. We found the principal components subject to failure are the vacuum pumps, the rf windows, and the coupling cavity intertank beamline components, which include the doublets, diagnostics, steer- ing dipoles, bellows, and a rad-hard vacuum valve. All the inlertank hard- ware is mounted on a pair of rails for quick removal and ease of alignment as shown in Fig. 4.9. The hardware is constrained to fit into a longitudinal space of 3.5 to 5 beta-lambda depend- ing on the energy point being consid- ered. The unit can either be fully disas- sembled on line, if conditions permit, to replace field coils, or it can be partially disassembled to changeout valves or bellows, ll can also be removed en- hig. 4.H. Coupled cavity linac tCC'L) septum cooling channels fur high-dulx factor operation. 54 Accelerator Technology Division Technical Highlights • AT-4 • Accelerator Design and Engineering beam direction Fig. 4.9. Quadrupole doublet alignment and quick maintenance hardware for radioactive applications. purity niobium welded together into a 805-MHz cavity chain. Unique fea- tures of this cavity include its ex- 9 tremely high unloaded Q (5 x 10 ) Seals when operated at superfluid helium temperatures (2K) and the high fields expected in the structure (12.5 to 15 Materials MV/m) at this relatively low frequency. The 805-MHz resonant frequency im- plies that a large surface area will be Weld exposed to high field levels. The suc- Preps cessful test of this prototype would be a benchmark in coupled cavity supercon- ducting technology. Fig. 4.10. Seven-cell high-gradient superconducting cavity showing areas of advanced technology. A representation of the seven-cell as- sembly is shown in Fig. 4.10. Indi- vidual cells are electron-beam welded at the equators and iris. The cavity subassemblies are then acid etched, tuned, and annealed at high temperature using titanium gettering to remove surface impurities. Cavity assembly inside the stiffening cage of six tita- nium tubes ensures that microphonic resonances exceed 240 Hz in the lowest transverse mode for adequate rf stability. Also shown in Fig. 4.10 is a four-bar flex linkage for fine tuning. This link- age is expanded in Fig. 4.11. Fine I I tuning is accomplished by deforming Fig. 4.11. Four-bar linkage used to achieve microtuning of the end half-cells of the end half-cells of the cavity chain. the seven-cell cavity. Accelerator Technology Division 55 Technical Highlights • AT-4 • Accelerator Design and Engineering One must be careful to work within the alloy consisting of 10% hafnium and Based on a highly favorable compari- elastic limit of niobium at superfluid \c/c titanium in niobium and tested il son between the finite element model of temperatures; however, the tuning for vveldability to pure niobium and a CERN/DESY four-cell cavity and sensitivity of the system is almost 320 resistance to superfluid helium leaks. actual vibration test data of that cavity, KHz/mm and the elastic tuning range is we analyzed the LANL seven-cell cav- ±41 KHz. To achieve this tuning The seven-cell design described above ity. Various stiffening schemes were range, the adjuster compresses or ex- is a research cavity with various uses, proposed and analysis was done to pands the end cells by only ±0.13 mm. including pion or proton acceleration at arrive at an optimum stiffened configu- Because of the extremely high Q of this medium energies. It is scheduled to ration. The resultant method for stiff- cavity chain, the linear yoke motion of undergo rf testing at full power in FY ening the rf cavity consists of a struc- the actuator necessary to achieve a 1- 1993. ture with six titanium tubes connected Hz step in cavity frequency is only 250 at either end with a bulkhead, to which A (2.5 mm). Vibration Analyses each cavity cell equator is rigidly at- Because of an inherent sensitivity to tached. This simple structure raised the The seven-cell design departs from microphonics. superconducting cavities first (lowest) transverse bending mode conventional engineering methods in must be designed to resonate at rela- from 37 Hz to more than 240 Hz. several other ways, including the use of tively high frequencies, despite the low Based on this success, we constructed a commercial metallic seals rather than stiffness of the basic thin-walled nio- similar analytical model to represent a indium. Indium is a good sealing mate- bium structure. To raise the fundamen- nine-cell cavity currently being devel- rial at superfluid temperatures, but tal frequencies of this type of cavity, oped at the Continuous Electron Beam tends to flake. Even the smallest par- proposed stiffening schemes must be Accelerator Facility, where a novel ticle falling into the cavity will destroy analyzed to determine if the required stiffening concept is being considered its high-field capability. To use the fundamental frequency levels are that encases the entire cavity within a commercial Helico-flex Delta-Seal achieved. Finite element models of thin-walled cylinder. requires that niobium alloy flange ma- several superconducting cavity struc- terial be selected with a Vickers hard- tures have been built to determine their Fine Frequency Adjuster Mechanism ness greater than 100. We selected an fundamental resonant vibration modes. The seven-cell cavity 'fine' tuning procedure involves elastic deformation of the cavity's end half-cells. We have back view front view designed an adjuster mechanism to effect this end-cell deformation via longitudinal translation of the cavity end flanges. It is mounted between the stiffening rod bulkhead and the cavity end flange (Fig. 4.11) and is similar to a four-bar linkage, but relies on flexures to eliminate the possibility of backlash and hysteresis. The adjuster is actuated through a yoke attached between two adjusters on either side of the cavity. Translation of the yoke rotates the cen- ter flexure, which in turn causes longi- tudinal expansion or contraction of the adjuster via a four-bar linkage motion of the outer flexures. A detailed three- dimensional, finite element model of the adjuster mechanism was created (Fig. 4.12), representing half of one adjuster. Although the niobium cavity is not directly included in the model, spring elements are used to represent its stiffness. We analyzed several different 6228 nodes loading conditions to explore the vari- 870 elements ous operating environments. Fig. 4.12. Finite element model of adjuster inechu 56 Accelerator Technology Division Technical Highlights »AT-4' Accelerator Design and Engineering Recently, a modified version of the obtained from the Accelerator Test conducted by N-2 personnel. Figure seven-cell fine-frequency adjuster Stand project in AT Division. The 4.13 shows the MEBT assembly cur- mechanism has been adopted by EMQs were retrofitted with new rently being used by N-2. Cornell's Newman Laboratory of mounting devices, which provided four Nuclear Studies for use on a single-cell degree-of-freedom precision adjust- We are currently designing a new superconducting cavity. ments. The mounting devices also MEBT for the next phase of this pro- incorporated kinematic mounts, which gram. It will include a 90° bend in the Support of Others allowed for removal and repeatable -Y direction, eliminate two of the replacement of the 100 lb. EMQs. A EMQs, incoiporate a new support Group N-2 FAA Moderate Energy small 1-cm-bore permanent magnet stand, and add diagnostics in the verti- Beam Transport (MEBT) System quadrupole (PMQ) was mounted on the cal leg. The new accelerator and Los Alamos National Laboratory's exit of the RFQ in a vacuum tight MEBT will be installed in the Group N-2 has purchased a 2.75-MeV holder. Provisions were made to moni- UHTREX facility at LANL\s TA-52. RFQ from AccSys Technology Inc., tor beam current along the beam line which will be used in experiments to using two Model 150 Pearson coils. Group N-2 Nondestructive Assay determine the feasibility of using a The entire MEBT assembly was Barrel Scanner resonance absorption technique to mounted on a support stand, which AT-4 personnel assisted Group N-2 in detect nitrogen bearing plastic explo- provided adjustment in the x, y, and z the design of a combined thermal/ sives. AT-4 was asked to design and axes. In July 1992, the MEBT was epithermal neutron (CTEN) fabricate a moderate energy beam assembled and aligned at AccSys Tech- nondestructive assay diagnostic. This transport (MEBT) system for use on the nology. Acceptance testing and opera- instrument will be used to interrogate exit of the RFQ. The MEBT contained tional experiments are currently being TRU waste and provide the required four electromagnet quadrupoles (EMQ) debuncher cavity pearson coil diagnostics cube Fig. 4.13. Moderate energy beam transport (MEBT) system assembly. Accelerator Technology Division 57 Teclmivul Highlights • AT-4 • Avcelvnaor Design and Engineering characterization for proper disposal. We have completed the design of the of moving + 2 inches about the center The device will be fabricated and com- top assemblies and work is progressing of the 8-inch test chamber in the x-y missioned at N-2 before shipment to on the details of the shielding door and direction and normal to the heam. the Idaho National Engineering Labora- target positioning assemblies. These tory for final installation. design modifications are intended to Currently the design is completed with minimize the amount of time required 50% of the hardware in procurement. The CTEN diagnostic is the latest ver- for redesign and use the skilled fabrica- A mock-up of this experiment is sched- sion of a long line of neutron counting tion craftsmen available at N-2. uled to start in early 1W3 in the devices, and the design is very similar LAMPF hot-cell area. After comple- to earlier versions. Design changes (;roup MP-7 LAMPF Support tion of the mock-up and off-beam test- have been limited to the addition of Helium-jet Experiment ing the assembly will he installed in the extra shielding and to upgrading the AT-4 is assisting MP-7 in an engineer- A-6 target area. Subsequent to the first instruments and mechanical drive ing and design effort in support of a experiment, we plan to design test trains. The most significant design LAMPF helium-jet experiment. This chambers that can be quickly removed change has been to replace the drive experiment requires a coaxial cylinder and reinstalled with new foils. irains used to manipulate the target and arrangement, which is shown in Fig. shielding door from chain and right 4.14. A maximum of 10 aim of helium A-2 Turret Area Upgrade angle gear drives to modular rodless gas is introduced at the center of the Personnel in AT-4 are also assisting in cylinder units with servo motor con- left end of the coaxial assembly of the upgrade to the A-2 target area at trols. The replacement of hand as- concentric cylinders, expanding LAMPF. Redesign work is in progress sembled drives with modular units through the cone to an 8-ineh-long to replace some existing hardware in allows lor significant savings in the chamber tilted with vertically mounted the target area, including vacuum tubes, amount of design detail required lest foils. The helium is expected to collimalors, and coolant lines. In the and in the assembly and ad- How parallel to the lesl foils in a lami- process of replacing this hardware, we justment phases. nar condition. At the right end of the S- are improving the current method of IQ inch How chamber is an array of capil- extracting heat from the target area. To lary tubes thai will extract the helium support this redesign effort, we are isotopes produced when the assembly developing several finite element is introduced into the LAMPF beamline analysis models to analyze (he target at the A-6 target area. The annulus area's heat transfer characteristics between the coaxial cylinders based on the beam's power deposition contains cooling water. on the target. Recommendations can This assembly has then be made on the size and quantity the capability of coolant channels necessary to coo! the collimalors and vacuum tubes. I'IK. 4.14. Helium-jet experiment nmxinl i \limle 5H Accelerator Technology Division Technical Highlights • AT-4 • Accelerator Design and Engineering Environment, Safety, and Health AT-4 also introduced a QA controlled Technical Memoranda (ES&U) document system that includes a formal cover sheet, distribution control, and The following AT-4 Technical Memos In the interest of improving the group's document change notice (DCN) control were written during the report period. formality of operations, AT-4 has of all revisions to the document. We adopted a graded approach with an have used this control to formalize the 1. D. Liska, "Vacuum Analysis of the incremental implementation plan to issuance and revision of manuals and 20-100 MeV BCDTL," AT-4:92- accomplish desired changes. The AT-4 procedures that have been designated 02, April 1992. environmental, safety, and health as needing better accountability. (ES&H) self-assessment plan has been 2. D. Liska, "Generalized Design For- completed, approved and implemented. The present AT-4 drawing vault is an mulas for Low Energy Electromagnetic Work is continuing toward accomplish- advanced system with a print machine, Quads," AT-4:92-03, April 1992. ing the goals outlined in the plan. Indi- CAD plotters, and computer links com- vidual training plans for employees bined with microfilm, disk and hard 3. D. Liska, "Vacuum System Design have been completed, and formal copy archives as well as DCN records, Cookbook," AT-4:92-04, April 1992. ES&H training for all AT-4 personnel computerized drawing lists, and classi- is in progress. A tracking and filing fied document records. The drawing 4. D. Liska, "Extreme Limits of Opera- system is in place that includes em- vault serves AT-3, AT-4, AT-5, and tion for Compact Electromagnetic ployee job specific technical training as AT-10. By combining and making Quadrupole Field Coils, Including well as ES&H training. We have con- efficient use of this resource, these Poletip Performance and Maximum tinued to generate and resolve ES&H groups have realized a significant cost Focusing Impulse ( AT-4 has completed the standard oper- AT-4 has dramatically changed in the ating procedures (SOP) and normal formality and awareness in which it operating procedures (NOP) documen- handles ES&H issues. tation for all testing operations within the group. Detailed SOPs and NOPs References for the high-power cryo test bed. the low-power cryo test bed, the pressure 1. S. J. Black and G. Spalek, "Calcula- and mass flow test stand, operation of tion of Mechanical Vibration Frequen- the drawing print machines and plot- cies of Stiffened Superconducting ters, and use and change out of anhy- Cavities," 16th International Linear drous ammonia tanks were written and Accelerator Conference, Ottawa, placed under quality assurance docu- Ontario, Canada, August 23-28, 1992, ment control. Other documents in- Los Alamos National Laboratory docu- cluded the test supervisors manual for ment LA-UR-92-2735. rf power conditioning and testing of DTL modules in the high-power cryo test bed. Accelerator Technology Division 59 Tvclmiciil Hixhlighrs • .17-5 • Railid-Fieijuciuy Teclmoltigy Introduction 61 GTA 51 Overview 61 High-Power rf System Develoment and Production 61 RF Syswm Integration with GTA 63 Aulimitiled Klystron Test Sliind.... 64 RF Controls 64 Feedforward Module 66 University ofTwente 66 Boeing APLE 67 Argonne Advanced Photon Source (APS) 67 Superconducting Super Collider {SSC) Laboratory Linac 67 Directed Energy Weapons Power Integration (DEWPOINT) 70 Plasma Source Ion Implantation 71 Gyration 72 Accelerator Production of Tritium (APT) 73 Accelerator Transmutation of Waste (ATW) and Accelerator Based Conversion (ABC) 73 fill A< ic/cralor Technnliig\ Uivisiim Technical Highlights • AT-5 • Radio-Frequency Technology Introduction conception by adding new Allen-Brad- High-Power rf System Development ley control systems. This has made and Production AT-5 has a primary mission to develop interfacing to the overall GTA control high-power radio-frequency (rf) sys- system easier. The GTA 850-MHz klystron amplifier tems for particle accelerators. The key system has many unique design fea- elements which make up the high- The 850-MHz conditioning stand is a tures. By combining two klystron am- power rf systems are the high-power stand-alone unit with its own power plifiers in the same oil tank with a generators with their associated support supply and capacitor bank. This sys- common high-voltage controller, we equipment and the rf feedback controls. tem was the original prototype for the realize significant economy of hard- 850-MHz amplifiers that will be used ware and system volume (Fig. 5.1). By The same expertise used to provide the on the drift tube linac (DTL) sections using modern high-voltage modulator high-power rf systems for accelerators of the accelerator. The system is used design techniques, we realize fiber is applicable to other areas. This pro- continuously while we are building the optic control. Additionally a feedback vides AT-5 with other opportunities to DTL portion of the rf system. Because circuit topology minimizes output am- develop technology and applications in we have a dual-klystron modulator, we plitude droop from the klystron. An radar systems, waste processing, and are able to condition cavities in the advantage of the mechanical layout is materials processing. conditioning vessel while using the that almost all electronic components other klystron to drive the first DTL are located on a removable lid, easing The following describes the programs tank for experiment 2A. maintenance and ensuring a minimal and activities of AT-5 during FY 1992. down time. In the unlikely event that a The low-level rf design supports both modulator unit fails, it can be quickly GTA field control and resonance control of swapped out and repaired off-site. the cavities. It also supports many Overview pick-up loops enabling the accelerator physicists to Thomson Klystron Tube In FY1992. AT-5 integrated the 425- monitor accelerator perfor- MHz rf equipment with the first of the mance. Additionally, we Solenoid 850-MHz hardware. This was AT-5's provided the rf reference first opportunity to demonstrate the rf rack that distributes the system as it was designed and built and 425-MHz and 850-MHz as it applied to an accelerator. reference signal to the Modulating various rf and diagnostic Anode AT-5 was responsible for significant components. Thomson to Varian input toward developing the controls Socket and computer interfaces as well as the The high-power rf system Adapter four main components of the rf system for the 10 DTL tanks for for the ground test accelerator (GTA). experiment 2D is under The four main areas we were respon- construction. This system sible for were the 425-MHz tetrode uses a 5-A high-voltage amplifiers, the low-level rf (LLRF) power supply and a single controls, the 850-MHz cavity condi- large capacitor bank that tioning stand, and the 850-MHz ampli- provides power to all 10 fiers for the beam line. klystrons. The integration Isolation of the system will be per- Transformer The 425-MHz tetrodes are 300-kW formed in FY 1993. After F|oatjng devices that supply power to the radio- this system is complete, we Deck - frequency quadrupole (RFQ) and to the will retrofit the condition- Modulator two intermediate matching sections ing stand to upgrade it to (IMS). AT-5 designed and built tour the production design of systems with one as a spare. Even the DTL systems. though the IMS requires only 50 kW for each cavity, all the tetrode designs GTA has been a showcase were the same allowing lor ease in for AT-5 and has allowed manufacturing. The tetrodes have us to demonstrate a wide worked very well since their installa- variety of expertise in tion and have been improved since their accelerator rf power. /•/,;;. 5./. Tuii-klvslmn modulator. \ccclerator Technology Division 61 Technical Highlights • .47-5 • Radio-Frequency Technology A view of the first GTA production modulator being installed is shown in Fig. 5.2. When completed, the if stations will be capable of produc- ing over 12 M\v of rl" power with a 2-ms pulse width and a 10-Hz rep- etition rate. The control hardware and software for the GTA klystron systems have been optimized from the engineer- ing prototype to provide more ef- fective system interface and con- trol. Each klystron stand has its own supervisory controller for equipment monitoring and sequenc- ing. Unlike the previous stand- alone rf stations, equipment param- eters and status must be transmitted lo the GTA master control room. Each smiion must be ready before the accelerator can operate. An example of an improved local con- trol screen is shown in Fig. 5.3. We designed the klystron capacitor bank's energy-storage system with personnel safety i • he utmost con- cern. Consequently, redundant discharge paths and charge-slate Fig. 5.2. Installation of first production modulator (left to right: Bill Reass. Bill North, monitors arc included. To increase John Bancroft, Phil Critelli). personnel safety, the GTA energy storage system includes ergonomic considerations and advanced pro- tection electronics. The capacitor bank uses interlocked and hanging ground hooks in the capacitor vault entry doorway requiring the opera- tor to physically remove the safety hooks before entry into the vault is possible. An electronic ground fault interrupter (GF1). a new implemen- tation for this type of hardware, effectively protects personnel and equipment from lethal shocks. The system is interlocked such th'il if the CiFI malfunctions or is noiioperalional. the power system will shut down safely and inhibit further operation. Attentive engi- neering has also yielded a clean, conma-free system design. A view ol the 500-k.l capacitor hank system is shown in Fiu. 5.4. Fig. 5.3. Local control screen for modulator. Accelerator Technology Division Technical Hixhlif;lits • AT-5 • Radio-Frequency Technology RF System Integration with GTA In FY 1992. substantial progress was made in integrating the GTA r!" system. In April 1992. the rt' systems team was formed to improve the reliability, avail- ability, and operability of existing equipment for experiment 2A; to pre- pare for expansion to support experi- ment 2D; and to bring new rf compo- nents on line. The final fabrication stages of the rf klystron stations for the DTL are shown in Fig. 5.5. Standard system engineering tech- niques were applied, albeit informally, to integrate the GTA rf system. Major hardware components were taken off line and run through an intermediate hardware and software integration and verification process. Several nagging reliability problems were attended to. Operator interface screens used for Fig. 5.4. Capacitor bunk (500 Id) for GTA (front tr back: Bill Reass. Bill North, controls gain scheduling were rede- John Bancroft). Fii>. 5.-i. Drift tube limn IDTI.I klwtmn \itiiiun Acceleratar Technolo^x Division Technical Highlights • ,47-5 • Radio-Frequency Technology signed for easier use and increased fault structure and will negotiate an inte- troller thai monitors and records the tolerance. All system components were grated requirements document and all status of the power supply, transmitter, then reintegrated, along with their re- required interface control documents and other safety interlocks. Thus, spective software, and the entire rf based on this work breakdown struc- LABVIEW automatically records the system was put through a verification ture. Formal verification processes will operating voltages and currents of each procedure. As a result, the typical rf be instituted to track compliance to klystron as the lube is being tested. turn-on time for operations was re- requirements. These efforts will further Three automated tests are performed to duced from 4 hours to under 112 hour. improve the design quality and imple- characterize the tube performance: Also, rf operations have been essen- mentation processes. swept frequency, power transfer, and a tially unintenupted during beam ex- Rieke diagram. An example of swept periments, with minimal operator inter- Automated Klystron Test Stand frequency results is shown in Fig. 5.7. action. The acquisition rate of quality Ten out of the twelve Thomson klys- experimental data during experiments The automated klystron test stand was trons were tested this year; test results is at an unprecedented high level due, designed and fabricated in FY 1992 to are compiled in AT-5 memoranda. in part, to these improvements in avail- verify the manufacturer's performance ability, reliability, and operability of data before the amplifiers are commis- RF Controls the rf system. sioned in the GTA. To monitor and record the status of a klystron, this test In FY 1992, improvements in the Several activities are under way to stand uses a LABVIEW-based data Downconverter (DCM), Vector Detec- ensure continued success in the GTA rf acquisition and control program (Fig. tor (VDM), and Upconverter (UPM) sector. We are developing a formal 5.6). The LABVIEW system interfaces modules allowed the design of the core product-oriented work breakdown with the Allen-Bradley PLC5/15 con- LLRF system to be frozen. In Febru- Fig. 5.6. Automated klystron test hurdwure. 64 Accelerator Technology Division Technical Highlights *AT-5 • Radio-Frequency Technology ary, the three 425-MHz LLRF systems Frequency sweep klystron #8, IC= 28.3 A, 1/5/93 and the first 850-MHz system were integrated into the GTA. The LLRF 1.20B+6 system for the RFQ was upgraded to include module improvements to allow 1 O0e+6 tor a reduction in size. As a result, operational problems in the original configuration were corrected, and the LLRF system for the RFQ was reduced from three to two chassis. The two new LLRF systems for the IMS cavities were also integrated as two-chassis systems. We successfully integrated the new 850-MHz system for the DTL #1 cavity and demonstrated its proper operation. To support the 850-MHz system, we upgraded the rf reference rack to include 850-MHz as well as O.OOe+0 853 855 425-MHz outputs. 845 847 849 851 Frequency (MHz) To deliver this hardware as tested and operational, certain process advances Fig. 5.7. Sample of automated klystron test results. were made. The Automated Test Lab was developed and constructed during 1992. The test lab includes the test console, test data storage, tested com- u ~A ponents, and instrument manuals as well as work space for component troubleshooting. The test console, shown in Fig. 5.8, contains a UNIX- based workstation capable of remotely controlling all the rack-mounted instru- ments and switching modules. All test software is written in Hewlett Packard's graphical programming language called VEE. We first demon- strated the facility in late 1992. A GTA UPM was completely tested with the facility. The console, testing software, testing fixtures, and cabling harnesses all had to be completed. During the testing, we reconfigured instruments, actuated switches, and recorded mea- surements in a totally automated man- ner for the complete module test. Fig. 5.H. Radio-frequency (rf) control module test lab. We performed system testing on all five of the systems to verify the LLRF subsystem integration process before delivery to the GTA. In addition, we created a definite cusiu:.icr and accep- tance test to enable system verification upon delivery to the GTA rf learn. Lastly, operator manuals for all the modules were completed to facilitate understanding and troubleshooting. Accelerator Technology Division 65 Technical Highlights • -\7"-5 • Kailin-h'retiueiicx Technnlngy Feedforward Module University of Twente The high-power radio-frequency sys- tem for the University of Twente pro- The Adaptive Feedforward Module, Los Alamos National Laboratory vided by AT-5 consists of JI L'.iiO-MHz which was developed lor the University (I.ANLi entered into a collaboration preamplilier providing in excess of of Twente, was tested in an experiment with the University of Twenle in the 1000 W of drive power (0.02'/r duty on the CiTA. The feedforward topology Netherlands to build a free-electron factor, 20-us pulse width) to the klys- is shown in Fig. 5.9. This feedforward laser (FEL) for research applications. tron; a waveguide run hetween the module demonstrated the use ol adap- AT-5 was tasked by the University of klystron and the accelerating structure; tive I'eeilt'orwurd technology and pro- Twente to build the rf controls, the if and a control terminal to monitor and vided a real method to extend the sys- driver, and the system interlock con- control the high-voltage system. The tem bandwidth beyond the closed-loop trols. AT-1 and AT-7 were tasked to klystron driver is a four-stage amplifier control limit. Beam transient distur- provide other elements of the accelera- with three solid-stale stages and one bances were nearly eliminated, an im- tor. (Figure 5.11 shows hardware in- planar-triode cavity-amplifier stage. possibility with I he existing system. stalled in the University of Twenle The monitoring and control system Figure 5.10 shows one of the error accelerator vault.) Based on previous consists of an Allen-Bradley Industrial signals before and after feedforward is hardware developed for the GTA, AT-5 Controller and a T30 terminal, which applied. The beam turn-on transient developed new designs for the control provides the user interface. In May was almost completely eliminated with software (based on LABVIEW com- 1992, AT-5 delivered and installed this the feedforward. Additional implemen- mercial software) and for the klystron equipment and it is operating without tation of the feedforward device on the driver because of the specific fretjuency problems. This hardware is shown in CiTA showed ii to he a useful replace- (1300 MHz) and power requirements the left rack in Fig. 5.11. ment for the current system. The theory (approximately 1 kW). may he used in the next generation of if The LLRF system developed for the control equipment. University ol Twente provides field control, resonance detection, accelera- adaptive feedforwar tor liming, diagnostic monitoring, and alarm and limit monitoring for their Accelerator T«(t) FEL accelerator. This LLRF system setpoint rf system e(t) was built into a single rack and in- Yd) h(t) cluded all LLRF equipment, an embed- ded Macintosh computer, a keyboard, a monitor screen, and all the necessary power conditioning. We also devel- /•/i,'. .\lA i l(tpo! The LLRF system was completely tested and integrated at LANL to verify its operation before .shipment. In addi- tion, this system was used on the 1300- MHz AFEL system at LANL and per- formed successfully. The system was shipped to the Netherlands in August 1992. The university was provided with a complete set ol documentation, including a system definition and user's manuals lor all devices in the system. The university personnel used these documents, along with our assistance ii;. \ /' I. /• fcillonuiiil w \itiu hsl rrutlh an (i I A. 66 Act t'lt'i'iitiir fCthtif i l)ivi\iun Technical Highlights • AT-5 • Rituio-Frequency Technology via electronic mail, to perform much of requires many (40-80) of these modules ratory on components for the linac the integration of the LLRF system for the APS project in 1993; therefore, for several years. The primary tasks with their accelerator. As a final train- LANL will be heavily involved in have been to develop and fabricate a ing step, an AT-5 engineer traveled to providing Argonne with these modules. 427-MHz tetrode-based amplifier for the University of Tvvente to help with test stand operation at the SSC and to the final integration and to train person- Superconducting Super develop and fabricate low-level rf nel to operate the LLRF system. Cur- Collider (SSC) Laboratory controls. In addition to providing rently, the initial results are favorable, Linac hardware, AT-5 has collaborated although full system operation will be with engineers at the SSC on their performed in FY 1993. AT-5 has been working with the Super- system design, particularly the design conducting SuperCollider (SSC) Labo- of the feedback control system. Boeing APLE In 1992, we delivered a VXlbus-based LLRF system to provide rf field con- trol, resonance control, timing, and diagnostic monitoring for the first four 433.33-MHz cavities of the Boeing Average Power Laser Experiment (APLE). We installed this system at Boeing in February 1992, and it was used successfully as part of their high- duty experiments that summer. Fur- thermore, we provided on-site training at Boeing to enable their personnel to understand, calibrate, and operate the LLRF system. In addition to the delivered system, we negotiated a contract to deliver Boeing another LLRF system to accommodate the remainder of the FEL project. The new system will include another 433.33-MHz control system similar to the existing one, a new rf reference system, and a phase-stabilized transport system. Argonne Advanced Photon Source (APS) Argonne is building a new facility called the Advanced Photon Source (APS). AT-5 negotiated a design con- tract with Argonne to modify some of our existing rf control equipment to operate at 2856 MHz with a higher measurement bandwidth. This included design modifications for the Downconverter. Envelope Detector, and Vector Detector modules. The design work has proceeded well, with Argonne receiving and testing the engi- neering prototypes. Presently, the final designs are 50% complete and should be finished early in 1993. Argonne Fig. 5.11. University ofTwenle hardware installed in acceleralo Accelerator Technology Division 67 Teduiical Highlights • AT-5 • Radio-Frequency Technology The firsv control system was delivered control systems were provided lo the width of 2 ms and a pulse repetition to the SSC in early FY 1992. In addi- SSC: in addition, the SSC relumed the frequency of 10 Hz. This design was tion, we loaned the SSC a cavity/ampli- cavity/amplifier simulator (after build- modified to meet a 600-kW pulsed fier simulator that allowed them to use ing a simulator of their own). requirement for the SSC with a pulse the controls, apply disturbances, and width of 100 us and a pulse repetition measure responses. The simulator re- SSC and LANL collaborated to modify frequency of 10 Hz. Fabrication was sults were used by the controls person- the design of the 425-MHz tetrode completed at LANL, ;>nd the amplifier nel at the SSC to justify further devel- amplifier developed for the GTA to was delivered to SSC and lesied in May opment and fabrication effort. In the meet a 427-MHz requirement for ihc 1992. The amplifier design included a last half of FY 1992. almost all mod- SSC. The GTA amplifier is a 300-kW new lower-loss input cavity for the ules needed for two more complete pulsed amplifier with a maximum pulse final amplifier and an upgrade in the Fig. 5.12. Tetrode amplifier (600 kW, 427 MHz) provided to Superconducting Super Collider (SSC) Laboratory. 68 Accelerator Technology Division Technical Highlights • AT-5 • Radio-Frequency Technology the torroids in the longitudinal direction. Two different ferrite cooling tech- The circuit's high-power excitation is niques are being pursued by the SSC. provided by a 4 cw 150,000 E tetrode The liquid cooling technique proposed tightly coupled to the cavity through a by AT-5 is being developed at the SSC, / coupling capacitor located between the while an alternate technique, using 1 / accelerating gap and the ferrite tuner. berylium oxide disks glued to the too- laQ ferrites, is being developed in Siberia Amplifier by the Institute for Nuclear Physics Tube Laboratory for the SSC. Tests at the Input powar, kW SSC during the past year have validated Fig. 5.13. Power transfer curve for SSC water as a suitable ferrite cooling fluid Laboratory tetrode amplifier. within the rf structure. amplifier computer controls from the In collaboration with the SSC power Pushbutton sheet-metal panel to a pro- supply group, AT-5 modeled the mag- grammable terminal. In addition, the net string in the LEB to characterize the high-voltage power supply design for magnet system's electrical design for the final amplifier was drastically im- the LEB, the first of five rings that proved over the GTA design and has make up the SSC. The LEB, which become our current baseline for this consists of 12 nearly equivalent magnet class of amplifier. The completed SSC cells arranged in a 570-m ring, is de- amplifier is shown in Fig. 5.12 and a signed to accelerate protons from 600 sample of the test results is shown in MeV to 12 Gev, and it can function in Fig. 5.13. Fig. 5.14. Low-energy booster (LEB) cavity one of two modes (Fig. 5.15). configuration for SSC. AT-5 has been involved with the SSC in designing and developing the low- energy booster (LEB) cavity since the beginning of the program at SSC. The Magnet 12 Fig. 5.15. Model of SSC magnet AT-5 participation resulted from our siring for the LEB. experience with perpendicularly biased, C. Bank 12 ferrite-tuned cavities. This experience C. Bank 1 was gained during the Advanced Had- ron Facility study at LANL. The basic configuration for the C. Bank 11 SSC LEB cavity remains as originally proposed by AT-5. This configuration is shown in Fig. 5.14. The cavity is a quarter-wave reso- nant structure, with the accelerating gap at the high-voltage C. Bank 3 end and the ferrite torroids at the high- Resonant control loop terminals (ryp) C. Bank 9 current end. Wave C. Bank 4 propagation is in the coaxial mode through- out most of the struc- ture up to the ferrite region, where the propagation is in the radial direction. The Magnet B Magnet 4 control bias H field C. Bank 8 direction is across C Bank 5 Accelerator Technology Division Technical Highlights • AT-5 • Radio-Frequency Technology The primary operating mode is as a 10- and fabricate a Hz rapid-cycling proton synchrotron. lightweight, state- series In this mode, capacitor banks are used of-the-art, space 1 Amp/Volt • resonance to make rhe entire magnet circuit reso- traceable. 500-kW nant at 10 Hz (Fig. 5.16). However, cw rf amplifier. »* • CiTE is designing • to because capacitor performance is af- * fected by temperature change and the and fabricating a * » • enclosure in which the capacitors are to I-kW solid-state * • • - lOOmA/V hybrid amplifier -20 • • be installed is unheated, total capaci- • • • tance in the system is expected to vary module (HAM) m as the daily ambient temperature varies. composed of • • • * * • Therefore, to maintain resonance at 10 solid-state triodes -30 — • • • • • * Hz. each capacitor bank includes addi- (SST)anda • • microchannel • tional trimming capacitors that may be • -40 10mA/V remotely switched in and out of the heatsink provided • • * • circuit. This resonant system elimi- by Lawrence • Livermore Na- nates the requirement of otherwise parallel 5 tional Laboratory. -50 having to provide (and recover) a large resonance" amount of reactive power. The specifications on the HAM are 1mA/V output power of 1 - -60 Because the acceleration cycle is from e-3 e-2 e-1 eO a 1 on kW cw, efficiency IrequBncy H' 600 MeV to 12 GeV, the magnet cur- .001 Hz 01 Hz 0.1 Hz 1 Hz greater than 65%, 10 Hz 100 Hz rent must swing a factor of 10, from and a gain greater 400 A to 4000 A. Because capacitors than9dB. In FY /"V.i». 5. Id. Magnet modeling results showing the 10-Hz resonance mode. cannot conduct direct current (dc). the 1993, GTE will capacitors are placed in parallel with inductors (chokes) so that the magnet test a submodule of the HAM that building blocks. After completing this system can operate with a biased sine- consists of four SSTs and will produce design. WEC will fabricate a 25-kW wave excitation. The primary focus of greater than 250-W cw. Upon comple- cw demonstrator that is derived from the modeling effort is to analyze the tion of these tests. GTE will begin the 500-kW space-traceable amplifier. electrical properties of this magnet fabricating the required number of The prime power for the amplifier will power system. HAMs to build a 25-kW amplifier. be designed by Electromcsh Institute in Westinghouse (WEC) is responsible for Russia. Currently, the institute is de- The second operating mode of the LEB designing a 500-kW s^lid-slate ampli- signing a hyperconducling alternator to is to cycle at 1 Hz as a ramped proton fier using the HAMs as fundamental our specification. synchrotron, with flat (dl/dt = 0) "front porches" and "'tops" for injection and sooo extraction (Fig. 5.17). This 1-Hz mode 1-Hz LEB Ramp Cycle | is accomplished by driving the magnet Magnet System Current and Voltage system with silicon controlled rectifier (SCR) power supplies using predeter- mined waveforms. We analyzed both the 10-Hz-resonant 3000 and the l-Hz-rump modes using as the primary analysis tool SPICK1 version 311. which operates on SUN worksta- 2000 tions. Directed Energy Weapons Power Integration 1000 (DEWPOINT) The goals of the Directed Energy Weapons Power Integration 0.0 0.1 0.2 0.3 0.4 0.S (DEWPOINT) program are to design Fii>. 5.17. Magnet modeling resnll\ \howins; llir III: operming wmlc. 70 Accelerator Jrihnology Division Technical Highlights • AT-5 ' Radio-Frequency Technology Plasma Source Ion _ High Voltage., /-'"" Power Supply""""• Implantation Capacitor Series Transmission Bank JLwLtch Lne The plasma source ion implantation I (PSII) process is a new manufacturing technology being codeveloped by AT Division, P Division, X Division, and Work 480V Piece MST Division in collaboration with 3-0 General Motors Corporation and the University of Wisconsin. The intent of this Cooperative Research and Develop- ment Agreement (CRADA) is to de- velop the PSII process on a large scale Diagnostics for the automotive industry. PSII is a process to tribologically alter material surfaces by immersing an object in a plasma and then attracting the ions to the object with a high negative voltage. Tribology is the study of the science of Fig. 5.18. Block diagram of PSII high-voltage modulator. friction, wear, and corrosion. For auto- motive applications, these objects may be drive-train components, machine tooling, or stamping dies. As an ex- ample of the process, a metallic part might be immersed in a nitrogen plasma and pulsed at high voltage to form a nitride surface layer. The PSII process shows promise as a replacement for the wet chemical bath (plating) process, thereby eliminating the associated haz- ardous waste. The AT-5 contribution is to design and develop the high-power modulator systems suitable for commercializing PSII. It is anticipated that the first pro- duction-line prototype PSII systems will require peak switching currents of 200 A or more at the 150-kV levels with a few percent duty factor (0.5 to 1 MW average). Further modulator and power system development is required to com- mercialize full-scale automotive assem- Fig. 5.19. Initial construction of PSII modulator (Ralph Cordova, AT-5). bly-line processing. These rep-rated systems may operate at kilo-ampere pulse currents at the 500-kV levels. A simplified diagram of the first modula- tor system is shown in Fig. 5.18. A view of the hardware (Fig. 5.19) shews a striking similarity to the GTA rf modu- lator. It is important to note that the switching technology used for this sys- tem is a direct technology spin-off from the Strategic Defense Initiative Organi- zation and GTA programs. Accelerator Technology Division 71 Technical Highlights • AT-5 • Riulio-h'rcuuencx Technology Gyrotron facility where US or Canadian mem- work lakes place. This method of pro- bers of NCMS can evaluate applica- cessing is being considered lor ceram- AT-5 is working with MST-4 to com- tions of the technology. The material ics bonding, enamel applications, Si mercialize a Ukrainian technology that processing stand consists of (1) an 84- and GaAs wafer processing, polymer involves processing materials with GH/. 35-kW, cw gyrotron v> ilh a mode hardening, and many other applica- directed millimeter-wave radiation. The converter lo take the overmoded output tions. AT-5 has received the gyrotron effort is a result of a CRADA between of the gyrotron and convert it lo a con- equipment from the Ukraine and is LANL and the National Center for centrated distribution suitable for use in awaiting funding lo refurbish the equip- Manufacturing Sciences (NCMS). The the processing chamber, (2) a super- ment. The system is expected to be CRADA involves taking a material- conducting magnet for gyrotron opera- operational 9 months from the receipt processing experimental stand from the lion; (3) a quasi-optical transport sys- of funding. The Ukraine's operational Ukraine, rebuilding it to meet US tem to duct the gyrotron radiation to a system is shown in Fig. 5.20. safety standards and quality expecta- processing chamber; and (4) a process- tions, and providing an experimental ing chamber where the experimental Fin. 5.20. Gyriitrim-based mute rials processing system installed in the Ukraine. 72 Accelerator Technology Division Technical Highlights ' AT-5 • Radio-Frequency Technology Accelerator Production of Accelerator Transmutation of We presented our ideas on the Accel- Tritium (APT) Waste (ATW) and Accelerator erator Based Conversion (ABC) rf Based Conversion (ABC) system to the Russian designers at a AT Division has been working for Los Alamos meeting, and they pre- several years on a proposal to produce The Accelerator Transmutation of sented their ideas based on their use of tritium with a high-energy, cw, proton Waste (ATW) and the Accelerator the regotron (another type of high- accelerator. An accelerator-based ap- Based Conversion (ABC) of plutonium power rf generator). Although the dif- proach to produce tritium offers envi- are additional applications of the high- ferences in approach are great, we have ronmental and safety advantages over a power proton accelerator technology corresponded with our Russian counter- nuclear reactor. In addition, an accel- being considered for APT. Design parts to better understand each other's erator is more easily scaled in both studies are taking place for all these ideas. design and operation for reduced levels applications, as funding permits. of tritium production. AT-5 has been directly involved in this proposal effort The generator of choice for all these because the rf power required is so applications remains the klystron, but enormous. The present design requires we have learned that the 1-MW CERN close to 300 MW of cw rf power. At klystrons have had several failures, and optimistic efficiencies, this would re- their life is about 25,000 hours, on quire more than 500 MW of prime average. Reliability concerns also limit power. the high-frequency power per klystron to 1.0-MW cw. The vendors have AT-5 has been working on the concep- improved the 352-MHz, 1.0-MW klys- tual design of the Accelerator Produc- tron to 1.3 MW, and they can now tion of Tritium (APT) rf system, in- make 1.0- MW at 77 kV. but this low- cluding the rf power generator type, the ers the efficiency to 62%. Thus, at 350 distribution system, the power condi- or 400 MHz, we can expect klystrons tioning, and component protection. A with 1.3-MW output power. However, large part of the effort is based on we have learned that the main cause of maximizing the system availability. downtime is not the klystron, but the Studies of existing systems are in cables and connectors, which require progress, including the Clinton P. considerable attention for maximum Anderson Meson Physics Facility system reliability. (LAMPF), Continuous Beam Accelera- tor Facility (CEBAF), European Center Another generator under consideration for Nuclear Research (CERN), Large for these applications is the klystrode Electron-Positron Collider (LEP), and because of its improved operating effi- others. ciency. The klystrode for the Chalk River Laboratory (CRL) in Canada Additionally, AT-5 has been working worked very well and has produced on the APT system design of the beam/ over 70% dc-to-rf efficiency under a cavity control. High-efficiency opera- wide variety of conditions (compared tion implies minimal control margin, to only 68% for the klystron, and then but minimal control margin implies only under optimum conditions). The reduced control response. Tradeoffs CRL klystrode is rated at 250 kW at must be considered. APT is a very 267 MHz. heavily beam-loaded accelerator and will require excellent control to reduce beam losses. Various schemes combin- ing both feedback and feedforward are being considered to meet the control requirements while maximizing operat- ing efficiency. Accelerator Technology Division 73 Technical Higliliahtx • AT-7 • Accelerator Theory and Free-Electron Laser Technology Introduction 75 Free-Electron-Laser Developments.. 75 APEX 75 AFEL Experiment 75 Microwi^ler 75 POP Experiment 76 Theory and Simulation 77 Theory 77 Simulations 77 Los Alamos Accelerator Code Group 80 Software Development and Maintenance 80 User Consultation 80 Distribution of Software and Documentation SO Gathering and Dissemination of Information HI Other Activities 81 Alpha Simulation Using Neutral Beams 81 XUV Plasma Source 81 SSC Collaboration 82 PSR Development 82 LANSCEII Proposal 82 ESN IT Collaboration 82 Accelerator Theory Notes 83 Technical Memoranda 83 74 Accelerator Technology Division Technical Highlights • AT-7 • Acceleralor Theory and Free-Electron Laser Technology Introduction densities of 7000 A/cnr were demon- FEL resonator with a permanent-magnet strated from the APEX photocathode, wiggler. The linac was conditioned with Group AT-7 provides theoretical and which significantly exceeded the previ- high-temperature bake and glow dis- computational support for AT-Divi- ously reported values for multialkali charge to achieve an operating vacuum sion programs and supports free-elec- photocathodes. The electron beam's of 1 x 10'' torr. It was high-power tested tron-laser (FED activities within AT- brightness at the end of the APEX 40- to 10 MW. Since early summer, the Division. We conduct theoretical MeV accelerator was measured to be 3 linac has reliably generated high-bright- analysis and develop computational x 10i: A/(m-rad): at a current of 135 A, ness electron beams. Using a 1-kW tools applicable to accelerator technol- making the APEX beam one of the drive laser, the highest peak current we ogy, including activities by the Los world's brightest high-current electron obtained was 200 A, and the highest Alamos Accelerator Code Group beams. Single-bunch transverse current density was 1 kA/cm:. At this (LAACG) and theoretical lesearch in wakefield effects were measured di- current level, the beam energy was the accelerator area. AT-7 manages rectly for the first time using a fast around 16MeV. The macropulse trans- FEL experiments by coordinating streak-camera technique, and a scheme verse emittance (normalized and rms) work of contributing groups and by for mitigating wakefield effects in a and energy spread were measured at 5 providing technical guidance to the high-current accelerator was developed. mr.i mrad and 1%. After all the beam FEL program offices for proposals, A Detailed report of APEX activities transport elements were installed and program directions, and external col- can be found in the APLE Free-Elec- tested, we were able to transport 70% of laborative arrangements. We engage tron Laser Program section of this this beam through a tube 25-cm long and in extensive research and development report. 2-mm in diameter. The permanent- on accelerator components and sys- magnet wiggler was assembled, tested, tems pertaining to the enhancement of AFEL Experiment and field corrected. The peak magnetic FEL performance. field was 5 kG, corresponding to an awof The Advanced Free-Electron-Laser 0.45 required for near-infrared operation. Free-Electron-Laser (AFEL) experiment is a research and Lasing with the AFEL system is ex- Developments development initiative to advance the pected in early 1993. A detailed report FEL technology required to build a of the AFEL activities can be found in APEX compact, robust, and user-friendly the Advanced Free-Electron Laser Initia- system for industry. AFEL develops tive section of this report. A Boeing/Los Alamos collaboration is technology in key areas such as the under way to build a high-average high-brightness beam, high-efficiency Microwiggler power FEL called the Average Power microwiggler, high-power optical sys- Laser Experiment (APLE). The goal tem, and user-facility. The microwiggler program's purpose of A.PLE is to demonstrate that a FEL was to investigate the pulsed-current can produce laser light with an aver- The AFEL system, now fully as- microwiggler's potential to greatly re- age power of 100 kW. A collabora- sembled, consists of a high-brightness duce the electron-beam energy required tive effort by many Los Alamos Na- electron linac with a photoelectron to reach short wavelength. We com- tional Laboratory (LAND groups has source, an emittance-preserving pleted the-physics design and are now resulted in the APLE Prototype beamline with permanent-magnet trans- developing an integrated engineering Experiment (APF.X). The APEX\s port elements, and a high-efficiency design (Fig. 6.1). The engineering purpose is to demonstrate the basic physics and technology of APLE at low-duty factor. The APEX FEL is driven by a 40-MeV electron accelera- tor that consists of a 1.3-GHz. 12- mode coupled-cavity linac with a 6- MeV photoinjector. The microbunch characteristics include a current of 0- 300 A and a pulse FWHM of 7-15 ps. Following the commissioning of APEX in FY 1991. the FY 1992 effort focused on physics experiments asso- ciated with the FEL operation. High- ' Slotted Wiggler Tube lights included lasing at a wavelength of 837 nm, the shortest to date for a Pulse Forming Network Los Alamos FEL. Ultrahigh current Fig. 6.1. An engineering design of the pulsed-citrrent microwiggler. Act elemtor Technology Division 75 Technica • AT-7 • Accelerator Theory and Free-Electron Laser Technology design shows a uniform wiggler field POP Experiment lube without loss requires a stable high- created by a pulsed current of 35 kA on quality beam. We completed an ex- a lube 305-mni long with an inner By the late 1990s, the United Slates' periment that showed the bright elec- diameter of 2 mm. The uniformity microelectronics industry will be re- tron beam at APEX could pass through required for the wiggler field leads to quired to have an advanced set of li- such a device with better than 90% submicron alignment tolerance required thography tools that will enhance its transmission. Second, the small-signal b\ the slotted tube. In this engineering competitiveness and support a position gain and detuning runge are small be- design, special attention has been fo- of leadership and sufficiency in defense cause of the short wavelength. The cused on eliminating field errors and and consumer electronics. Los Alamos cavity length has to be controlled to 1 selecting construction materials. The is proposing to extend the traditional um, a sensitivity that is 100 times more field errors include static dipole and optical lithography process with FELs stringent than our previous experi- quadrupole errors in the body and at the as powerful and tunable light sources of ments. To solve this problem, we pre- ends of the wiggler. We measured and extreme ultraviolet (XUV) radiation to set the cavity length by lasing at a corrected these errors using the pulsed- produce gigabit integrated circuits with longer wavelength or by using the drive wire technique (Fig. 6.2). In addition, features of 0.15 um and less. laser. Mirrors that have high we developed a field-correction system reflectivity at two different wave- to produce time-dependent dipole and A POP experiment is being carried out lengths were specially fabricated for quadrupoie fields in the wiggler. These at the APEX facility. The goal of the this purpose. Third, the pulsed-current fields will compensate for changes in experiment is to lase with a microwiggler is used to enhance FEL the error fields caused by thermal heat- microwiggler at a fundamental wave- gain at short wavelength with available ing over the macropulse duration. The length of 850 nm and then at the third electron-beam energy. The materials were chosen to provide good harmonics of 250 nm. The POP experi- microwiggler is a recently developed structural stability and good vacuum. ment is an extremely challenging ex- device whose characteristics remair; to This engineering design is now being periment for many reasons. First, the be fully understood. tested in the proof-of-principle (POP) microwigglers are 305-mm long tubing e>: periment. with a 2- to 3-mm inner diameter. For The good response of the photomulti- the electron beam to traverse such a plier at short wavelengths allows us to measure the spontane- ous emission and to use it as a diagnostic tool. We conducted a series of experiments to under- stand the measured spontaneous emission. However, we have yet to be successful in las- ing. The problems encountered are caused mainly by the microwiggler's un- known properties, which include field errors and nonuniformity, heating effects, and vacuum property of material used. A third version of the microwiggler is being built and will be tested in January 1993. Fig. 6.2. Experimental setup for measuring the field uniformity of a pidsed-current microwiggle 76 Accelerator Technology Division Technical Highlights • AT-7' Accelerator Theory and Free-Electron Laser Technology Theory and Simulation hybrid (TE-TM mixed) modes. In their beams from photoinjectors, typical 1956 paper, Panofsky and Wenzel say emittance-measurement techniques Theory they restricted their work to beams (e.g.. quadrupole scans or multiple moving through cavities excited in TE sc: -. is) consistently underestimate the We developed software and analytical or TM modes. We reexamined their emittance. The error can be as large as tools for several related projects: accel- work and showed the following given a factor of 2 to 4 resulting from the erator production of tritium (APT), their assumptions: (1) the particles are nonthermal electron distribution. The accelerator transmutation of waste rigid enough that the particle orbit is unfortunate side effect is that it is now (ATW), and accelerator-based-fusion not substantially affected in its passage more difficult to match electron beams materials testing in collaboration with through the cavity, and (2) the trans- into various beamline elements, such as the Japan Atomic Energy Research verse electric field vanishes at each end bends or wigglers that require explicit Institute (JAERI). All these projects of the cavity, then they have implicitly knowledge of the beam's phase space. require a high-current proton or deu- derived a result that is not restricted to teron linac with very low-beam loss. In TE and TM modes. More specifically, Our collaborations with Boeing have FY 1991, AT-7 personnel analyzed the the transverse momentum imparted to a contributed to the APLE beamline beam rms equations for such systems charged particle moving in the z direc- design. We developed simulation tools and developed software for performing tion through a resonant cavity of length to model the actual nonsymmetric rms simulations and for finding d is given by magnetic field in the APLE-injector matched beams, including the effects of experiment by including direct Biot- acceleration, nonideai quadrupole fo- Savart integration of the current in cusing, realistic gap fields, and rms PARMELA. Using this tool, we cor- space charge. This software was used where e is the charge of the particle, a> rected the field errors by carefully along with TRACE-3D and PARMILA is the angular frequency and V±E_ is using transverse stacks of permanent in support of the JAERI collaboration the transverse gradient of the c compo- and is expected to be useful in all the nent of the electric field along the path projects described above. of the particle. This more genera! re- 150 sult gave valuable insight into the study of a proposed deflector for APT. We also studied beam halo formation 07S and subsequent beamline interception. Our work on beam-halo growth began We analyzed the effect of transversely with the APT project, which showed rotated quadrupoles mixing the trans- 0 how to create exactly stable nonlinear verse phase spaces. Assuming that the £•:'?•.-.•/ symplectic maps. However, the ex- initial phase spaces are uncorrelated, amples given were purely mathematical we have shown that there is an emit- • 0/b and not of practical interest. If realistic tance growth in both planes of maps were found, we could build high- • ISO intensity linacs or large, colliding . -. sirr2# -7 6 -3 8 0 3 8 7 6 beam-storage rings with the appropriate Ag- = , g,,ff33 In, NC000: 3982 ' X VS PHI-PHIS nonlinear magnets that would ensure /" nonlinear stability (extremely small where the quadrupole of focal length/' 150 particle loss). Recent work has concen- is rotated by an angle 6 transversely. trated on stabilizing real maps that dM and a,, are beam sigma-matrix might be of interest for high-intensity elements. 075 linacs. Maps from very realistic mod- els have been stabilized in an ideal Simulations U sense. One important realization was that stability can be achieved without The APEX beamline has been simu- .J.'; changing the linear or the first order lated extensively. We have calculated U/b nonlinear terms. Thus, in a circular the effects from transverse wakefields machine, for example, one could (confirmed by actual measurements achieve stability without changing the shown in Fig. 6.3), transversely rotated -7 6 -3 8 0 3 8 tunes of the chromaticity correction. quadrupoles. and virtual cathode for- , NGQQOz 3984 mation just off the photocathode. We "" X VS PHI-PHIS AT-7 has also examined the applicabil- have also carefully simulated the emit- Fig. 6.J. Time-resolved horizontal heain ity of the Panofsky-Wenzel theorem of tance-measurement techniques and .site at screen (a) without transverse standing-wave deflectors excited in have determined that for electron wakefields. lit) with transverse wakefields. Accelerator Technology Division 77 Technical Highlights • AT-7 • Accelerator Theory and Free-Electron Laser Technology magnets. In addition, we used We designed a postaccelerated RKA efficient power extraction. For longer PARMELA to design the beamline (Fig. 6.4) with the simulation tools pulse lengths (beyond 1 ms), the elec- and to demonstrate the match into the developed for the relativistic klystron tron beam cannot be shorted out, and bends and the wiggler. We also per- amplifier (R.KA). We have learned that the beam energy in the potential fields formed beam-interception calculations the maximum harmonic current modu- is lost. However, if the beam is in the wiggler to ensure that the power lation from bunching within a cavity as postaccelerated after bunching, the interception is acceptable, and three- a function of the space charge has two high-harrnonic current is preserved and dimensional field simulations on the peaks: one when the beam is ballistic all the additional power added to the APLE cavities to determine the field and a second, larger one, when the bunch can be extracted, resulting in asymmetry from the cavity drive slots beam is close to the space charge limit. high-overall efficiency. This device and power losses. The fundamental harmonic current can has both higher harmonic currents and be as much as 1.6 limes the average significantly shorter lengths than a AT-7 has designed and simulated a current at the second peak. In this single diode RKA with the same beam 70-MeV beamline for plane-based regime, most of the beam's initial en- current and total voltage. We also FEL applications. We accelerate a 5 ergy is captured in the beam's potential noted that this device could be used to nC, 20 ps bunch to 40 MeV at which fields. We discovered that by including extract efficiently at the third, and point it is bunched in a chicane an idler cavity, the higher harmonics possibly higher, harmonics and could buncher to 800 A. The bunch is ac- (i.e., second and third) have nearly the compete with other sources at 11.4 celerated another 30 MeV to a total of same current as the fundamental. For GHz in regards to size, power, and 70 MeV. After matching this beam to short pulse lengths (around 100 ns), the efficiency. a wiggler. FELEX simulations electron beam's Coulomb fields can be showed up to 20% energy extraction short circuited in the output cavity. from this bunch. This allows us to bunch close to the space charge limit and obtain the high- harmonic current, but yet still have 11.0 8.2 - x 5.5 - 2.7 0.0 0.0 187 37.5 56.2 75.0 X1 3.65 .I" '. 2.49 - 1 32 0 16- -1 00 0.0 18.7 37.5 56.2 75.0 X1 /!,' 6.4. Panicle-in-all simulation of u post-accelerated relativistic khslron. 7H Accelerator Technology Division Technical Highlights • AT-7 • Accelerator Theory and Free-Electron Laser Technology MAFIA postprocessors DIFF, FIELDS, and POWER were written as tools tor the MAFIA user (Fig. 6.5). Program DIFF subtracts the electric and mag- netic fields of one MAFIA run from another, allowing the user to see the effect of a perturbation. Program FIELDS interpolates the MAFIA calcu- lated electric and magnetic fields in between mesh locations and allows for easier interface with particle-pushing codes. Program POWER computes stored energy, total power loss due to finite conductivity, individual power loss for each metal, and power-loss densities for the metals specified by the user. These codes were used in the analyses of the APLE design, the APEX linac, and the deflecting cavity studied for APT. The electron-pushing code PARMELA has been ported to the UNICOS ma- chines, and the various versions of PARMELA have been combined into a unified version. This new code in- cludes both external POISSON and MAFIA fields and three-dimensional injector solenoid fields created by Biot- Savart's integration of current loops. Previously, a code to simulate beam- beam effect in the strong-strong regime was developed using moment methods and was shown to be very fast. The limitations of the code were that it was only a two-dimensional code and that an accelerator ring was modeled only as a linear device. These restrictions have recently been removed. The new beam-beam code for strong-strong regime simulations includes three- dimensional effects, such as synchro- betatron resonances due to finite cross- ing angle and the interaction of the beam-beam nonlinearities with the machines nonlinearities. In addition, tracer particles have been added for purposes of visualization. Fix. 6.5. luiATW deflector modeled In MAFIA. tbl Electric field plot produced by MAFIA postprocessor. Accelerator Technology Division 79 Technical Highlights • AT-7 • Accelerator Theory and Free-Electron Laser Technology Los Alamos Accelerator (Fig. 6.6). Release 4 is available for INGRID mesh generator as a first step Code Group various platforms, including Sun toward performing simulation with SPARC, HP Series 700, IBM RISC/ unstructured grids. Funded by the Department of Energy to 6000, SGI, VAX/VMS, and Cray/ serve the US scientific community, the UNICOS. User Consultation LAACG provides software and services to design and analyze particle accelera- The LAACG expanded its activities The LAACG consulted with many tors and beam-transport systems. Its related lo ARGUS, a three-dimensional researchers at national laboratories, main activities include developing and family of simulation codes developed universities, and in industry. Most maintaining software; consulting with at Science Application International consultation involved helping research- others; distributing software and docu- Corporation (SAIO. ARGUS contains ers correctly use codes to perform cal- mentation; and gathering and dissemi- modules for steady-state and time- culations and simulations. nating information, in recent years, the dependent particle-in-cell simulations code group's services have extended to and for time domain and frequency Distribution of Software international users. domain electromagnetic simulations. and Documentation Code group personnel have used Software Development ARGUS to model the Large Orbit The LAACG distributes software in and Maintenance Gyrotron experiment. They also at- three ways: electronic transmission, tended a course at SAIC to become magnetic media (tapes), and access to The LAACG completed two major expert users and to provide SAIC with software at NERSC. The LAACG also revisions to the widely used POISSON/ guidance in preparing the 1993 release distributes documentation. From Janu- bi JPERFISH codes used to design of ARGUS through the LAACG. Fig- ary to June 1992, the LAACG deliv- accelerator components, including ure 6.7 shows an example of ARGUS ered software to over 150 contacts magnets and radio-frequency (rf) cavi- output. (including system managers) and ties. The first major revision was Re- mailed out over 900 documents. These lease 3, which contained bug fixes, During FY 1992 Cray computers at Los figures increased dramatically in the physics enhancements, and expanded Alamos and the National Energy Re- latter half of 1992 because of wide- graphics support. The second major search Supercomputer Center (NERSC) spread interest in POISSON/ revision, Release 4, included removing at Livermore switched to the UNICOS SUPERFISH Release 4. all bit packing, increasing FORTRAN- operating system. Code group person- 77 standardization, including the pre- nel developed UNICOS versions of processor FRONT, improving graphics several programs, including MAFIA capability based on the X-Windows 2.04 and PARMILA. In addition, corie protocol, and producing arrow plots group personnel began using the Fig. 6.6. Arrow plul of field calculated with SUPEPF1SH codes. 80 Accelerator Technology Division • Accelerator Theory and Free-Electron Laser Technology Gathering and Dissemination of Other Activities realized that neutral beams developed Information for the neutral particle beam (NPB) Alpha Simulation Using Neutral program could provide much more During the 1992 Linear Accelerator Beams realistic experimental simulations of Conference at Ottawa, Canada, the the possible effects at conditions much code group organized an information Effects such as instabilities or anoma- closer to fusion conditions. Before we booth to introduce code group services lous transport from the alpha particles discovered the usefulness of the neutral to users. In addition, it held a "town produced in burning plasmas may particle beam, a cw 1.7 MeV D- beam meeting" to hear users' concerns re- affect the performance of ignited fu- with a current of 125 m A in one mod- garding accelerator code development sion machines such as ITER. It is ule was needed, and another 4 to 16 and availability. The LAACG is now important to obtain information about modules were required to inject ap- co-organizing the 1993 Computational these effects soon so the best designs proximately the same free-energy den- Accelerator Physics Conference, which for these future machines can be pro- sity into a device, such as TFTR or will be held in February 1993. duced. Experimental simulation has DIIID, at full-magnetic field under been done in existing devices by in- near-fusion conditions as would be jecting neutral 250-KeV beams with produced in a burning plasma. Single scaled magnetic fields. However, we modules with these parameters are being developed for the NPB program. XUVPlasma Source We are seeking funding for a unique electron beam-driven plasma XUV source that is currently in conceptual development. The source consists of a 5-MeV electron beam and a tenuous plasma of neon or nitrogen. The elec- tron beam is a continuous stream of pairs of electron bunches. The first bunch has low charge and is 10 ps long; it partially ionizes the gas into plasma. The second bunch has a high charge of 5 nC and is less than 1 ps long; it will deposit 75% of its energy into the plasma via wakefield interaction. The resulting hot, dense plasma quickly (i.e., within 100 ps) loses energy by XUV line radiation. The output wave- length depends upon the chosen gas type and its pressure. The output power level depends upon the gas type and the parameters of the input electron beam. Compared with similar schemes for example, the laser-driven plasma, this scheme has several advantages. First, an rf electron beam avoids the particulate contaminates of a laser produced plasma. Second, plasma recombination to its initial atomic state allows the gas to be recycled through a closed-loop recovery system. Third, it is "granular" (i.e.. acceptably small unit size and cost) enough to be of interest to soft x-ray lithography systems. Fourth, this approach is adjustable to yield short (15 nm) or long (60 nm) Fin. 6.7. Typical output from the ARGUS code. Accelerator Technology Division 81 Technical Highlights • AT-7 • Accelerator Theory and Free-Electron Laser Technology wavelength irradiance by changing only PSR Development LANSCEII Proposal the composition of the flowing gas (e.g., neon versus nitrogen). This operation's We observed a fast transverse instabil- Recently, serious consideration has versatility is an attribute not offered ity with beam loss in the 800-MeV Los been given to a next-generation accel- before to the semiconductor manufac- Alamos proton storage ring when the erator-driven spallation neutron turing industry. Fifth, this design has injected beam intensity reached 3 x 10n source at Los Alamos. Conceptual multisided output access, each yielding protons per pulse. Understanding this design is in process. We helped de- irradiance suitable to illuminate a single instability and the methods to control it sign the lattices for the 800-MeV ring stepper. Sixth, this source has upgrade have taken on new importance as the and the 2-GeV ring, provided the power potential because the injector- neutron scattering community consid- preliminary stability studies, and accelerator structure does not have an ers the next generation of accelerator- studied the design's longitudinal operational thermal limit. driven spallation neutron sources, phase-space painting scheme. which call for peak proton intensities of 4 SSC Collaboration 2 x 10' per pulse or higher. Previous ESN1T Collaboration observations indicate that the instability Our collaboration with the Supercon- is probably driven by electrons trapped The Energy Selective Neutron Irradia- ducting Super Collider (SSC) theory within the proton beam. Theoretical tion Testing project is a joint venture group concentrates on the rf counter study has shown that beam leakage in between LANL and JAERI. An ac- phasing and beam-loading stability the interbunch gap leads to electron celerated deuterium beam is directed problems for the low energy booster trapping. In 1992, several experiments to a lithium target, producing neutrons (LEB). To avoid multipacting in the rf were carried out by using the newly used for fusion materials research. cavities, the cavity voltage must be implemented "pinger" and by varying Currently, we are considering a 2- to above 20 kV. However, to achieve the the machine transition gamma to ex- 3-MeV RFQ at either 120 MHz or 175 desired capture during injection, the rf plore further the nature of the "e-p" MHz, with a 75- to 125-mA deute- voltage must be about 10 kV. To avoid instability. Currently, we are examin- rium beam, followed by a 35- to 40- this problem, we plan to counter-phase ing the experimental data and writing a MeV DTL. the rf cavities, 50%. Consequently, the simulation program to study the longi- cavities can be run above the tudinal space-charge effects. multipacting limit, yet the injection capture can still be optimum. In addi- tion, the cavities can be easily rephased when higher voltage is needed. We have shown that if the rf amplifier can deliver 120 kW per cavity, there will be enough rf power to maintain the correct voltage when the tuning error in the cavities is moderate. Higher harmonic rf systems are used in synchrotrons and storage rings to increase the bunch length and the spread of the synchrotron frequency to reduce the space charge effect and to dampen the longitudinal instabilities. We also examined the beam-loading stability in an rf system with a higher harmonic by directly in- vestigating the equations derived from the equivalent-circuit model. The sta- bility conditions for the LEB have been derived from the linearized equations. 82 Accelerator Technology Division Technical Highlights • AT-7 • Accelerator Theory and Free-Electron Laser Technology Accelerator Theory Notes The following AT-7 Accelerator Theory Notes were distributed during the report period: 1. M. J. Browman, "Testing Program Power," AT-7:92-ATN-l. 2. M. J. Browman, "Effect of Tuning Stubs on the Power Loss in a Four Slot Cavity," AT-7:92-ATN-2. 3. M. J. Browman, "Generating MAFIA Azimuthally Symmetric Cavities from a Two-dimensional Cross Section," AT-7:92-ATN-3. 4. R. Ryne, "Normal Analysis of Anharmonic Oscillator, including Envelope and Emittance Growth Calculations," AT-7:92-ATN-4 5. R. Gluckstern/R. Copper, "Beam Breakup Estimates for a Superconducting Proton LINAC," AT-7:92-ATN-5. 6. R. Gluckstern, 'Transient Effects in the Slotted Cylinder," AT-7:92-ATN-6. 7. C. Fortgang, "Field Correction for a One-metered Long Permanent-Magnet Wiggler," AT-7:92-ATN-7. 8. J. Merson, "Power Densities for Superconducting RFQ LY-10-14," AT-7:92- ATN-8. 9. J. Merson, "HALAST and GMHALD on UNICOS," AT-7:92-ATN-9. 10. J. Merson, "SPCG 4 and GRAF on UNICOS," AT-7:92-ATN-10. 11. T. Wang, "Robinson Instability with a Higher RF Harmonic," AT-7:92-ATN-ll. 12. M. J. Browman, "The Panofsky - Wenzel Theorem Revisited,'" AT-7:92-ATN-12. Technical Memoranda 1. J. Merson, "Cell Dimensions used to Generate SFDATA Table for ATW 350 DTL,"AT-7:92-TM-l. 2. M. J. Browman, -'Program Plots," AT-7:92-TM-2. 3. M. J. Browman, "Program Power," AT-7:92-TM-3. 4. J. Merson, "Dimensions of Superconducting RFQ LY-7-7," AT-7:92-TM-4. 5. J. Merson, "Prior work done on Behavior if Multiple Beams in an RFQ," AT-7:92-TM-6. 6. J. Merson , Wangler, "Superconducting RFQ LY-7-15 Dimensions," AT-7:92-TM-7. 7. J. Merson, "Power Densities and Fields for Superconducting RFQ LY-7-15," AT-7:92-TM-8. Accelerator Technology Division 83 Technical Highlights • AT-7 • Accelerator Theory and Free-Electron Laser Technology 8. J. Merson, "Total Power Loss for Superconducting RFQ LY-7-15," AT-7:92-TM-9. 9. J. Merson, Wangler, "Dimensions of Superconducting RFQ LY-8-7," AT-7:92-TM-10. 10. J. Merson, "Power Densities for Superconducting RFQ LY-8-7," AT-7:92-TM-l 1. 11. J. Merson, "Frequency, a Stored Energy and Vane Voltage of LY-8-7 from MAFIA Superconducting RFQ," AT-7:92-TM-12. 12. J. Merson, "Fields at End Wall of LY-8-7," AT-7:92-TM-13. 13. J. Merson, "Superfish Definition and Results for Superconducting RFQ SCRFQ 11," AT-7:92-TM-15. 14. H. Takeda, "Otimization of APLE Photoinjector with the Injector Solenoid Field Modeled by the Biot-Savart Law," AT-7:92-TM-16. 15. H. Takeda, "Optimization of ESNIT RFQ at 175 MHZ," AT-7:92-TM-17. 16. J. Merson, "End Region Dimensions," AT-7-.92-TM-18. 17. J. Merson," Field's for Superconducting RFQ Geometry ZY5-AJ," AT-7:91-TM-24. 18. J. Merson, "Summary of Super Conducting RFQ Mafia Calculations," AT-7:91-TM-25. 19. M. J. Browman, "Comparison Between Previously used Side-complied Geometry and APEX Cavity," AT-7:91-TM-26. 20. M. J. Browman/Rodenz, "Proposed Changes to M3," AT-7:91-TM-27 21. M. J. Browman, "PARMELA Input for APLE Cavities with Different Plot Configurations," AT-7:91-TM-28. 22. M. J. Browman, "Effect of Tuners on the Fields in an APLE Cavity," AT-7:91-TM-29. 23. J. Merson, "NERSE Unicos Class Highlights," AT-7:91-TM-30. 24. A. Lombardi, "Wakefields Effect in Microwiggler," AT-7:91-TM-31. 25. J. Merson, "Source of SF Data used for Current ATW PARMILA Calculations,"AT-7:91 -TM-32. 26. J. Merson, "Preliminary ATW DTL Dimensions," AT-7-91-TM-33. 27. J. Merson, "POISSON/SUPERFISH Mafia and NERSC," AT-7:91-TM-34. 28. J. ivlerson, "Power Density in Selected Cells of ATW DTL 35od," AT-7:91-TM-35. 29. J. Merson, "Power Requirements Dimensions of ATW 350 DTL," AT-7:91-TM-?5. 84 Accelerator Technology Division Technical Highlights • AT-7 • Accelerator Theory and Free-Electron Laser Technology Accelerator Technology Division 85 Technical Highlights • ATS • Accelerator Controls and Automation Introduction 87 Background 87 Accelerator Control 87 Operations 87 Waveform Acquisition 88 Off-line Testing 88 Commissioning and Automation Software Tools 88 Phase Scan 88 Steering 88 Automatic if Structure Conditioning 88 Video Beam Profiles 88 Ion Source Automation 89 Control System Hardware 89 Operational Support 89 Fast-Protect System Development 90 Optically Isolated Binary Output Module 90 Step-Motor Control 90 Transient Digitizer 90 Next Generation Computer for IOCs 90 Binary Output 91 Nonvolatile IOC Memory Module .'. 91 Electronic Computer Aided Design (ECAD) Support 91 Computing Support 91 86 Accelerator Technology Division Technical Highlights • ATS • Accelerator Controls ami Automation Introduction We installed a complete vacuum Operations control system for the new DTL vessel. In FY 1992, AT-8's major efforts Pumps, gauges, and valves are all Integration and operation have become included producing, installing, and operable through the control system as important issues as hardware is added commissioning of the control system for well as from a manual control panel. to GTA and experiments have become the intertank matching section (IMS) The control system provides interlocks more complicated. New application and the first drift tube linac (DTL) that can automatically shut off devices software and some hardware have been section of the Ground Test Accelerator or close valves in the event of an customized to assist in operating the (GTA). Typically, AT-8's tasks are to equipment failure. The control system accelerator effectively and safely. generate the hardware and software also provides automatic trending of necessary to control and monitor vacuum readings. A single IOC The accelerator safety systems now accelerator components and subsystems, provides control and monitoring of the include a control system integrity then to integrate, and test the controls on radio-frequency quadrupole (RFQ) check. As part of the integrity check, the beamline. vacuum system and the first DTL the run-permit system monitors a vacuum system. 'heartbeat' from each IOC that controls Background critical accelerator operations. If any The DTL, like the RFQ, operates at of these front-end processors fails to Two experiments which studied the cryogenic temperatures. A large respond or is operating abnormally the performance of the IMS and DTL were number of silicon diode temperature accelerator is automatically shut down. executed. Puring these experiments, transducers are used to monitor the The control system can also disable the controls personnel manned two shifts a temperature of the DTL structure and accelerator when other abnormal day to assist with accelerator operation various points along the cryogenic conditions are detected, such as a and data acquisition. The distributed manifolds. Temperature readings are vacuum reading that is too high or architecture control system for the automatically logged by the control steering magnets that are not set within experiments consisted of about 15 front- system. The desired operating set-point tolerance. end VME-based INPUT/OUTPUT is typically 25 to 35 K. If the control controllers (IOCs) with associated system detects any temperatures above We endeavored to create software tools instrumentation, and approximately 10 50 K, it automatically disables beam that aid experiments in effective and color work stations used as operator production. efficient accelerator control. The data interfaces running the EPICS software. archiving software has been tailored to The DTL module is supported by five users' requests. A new capability has This year marked the first use of the mechanical positioners, much like the been developed that can automatically GTA control room. Previous experi- RFQ. This enables the structure to be vary an accelerator parameter through a ments had been operated from a translated along orthogonal axes after series of set-points and collect data at temporary control room amidst the the accelerator has cooled to cryogenic each set-point, resulting in increased electronic equipment racks. Operating temperatures. These positioners are efficiency over repeated manual from the control room was a definitive operable from the control room, which adjustments and data acquisition. A test of control system reliability and transforms the operator's desired x/y data retrieval tool extracts previously functionality, as neither the accelerator coordinates into position commands for archived data and provides plotting, nor electronic equipment could be each of the five positioners. translation to several foreign computer observed directly. file formats, and statistical analysis. We installed another rf power system Other tools include an on-line operator Accelerator Control controller for driving the DTL. The log, an alarm manager that provides control system interface is nearly orderly notification of anomalies, and a We installed the first DTL in a new identical to the ones installed previ- graphic timing control program that vacuum vessel that is planned to contain ously for the RFQ and IMS. Through displays accelerator timing settings as a five DTL modules. The control system the control system, the operator may set timing logic diagram. monitors and provides supervisory and monitor parameters such as phase control for the vacuum, cryogenic and amplitude for any cavity. RF temperature, radio-frequency (rf) power. engineers may control more detailed DTL tank positioners, frequency tuners, settings such as system calibrations and and a steering magnet. An additional closed-loop control coefficients. three IOCS were installed to accommo- date new DTL controls, rf controls, and beam diagnostics instrumentation. Accelerator Technology Division H7 Technical Highlights • AT-8 • Accelerator Controls and Automation Waveform Acquisition VAX system for use by RESOLVE, a fully tested. We expect the problems to beam-tracing program. In addition, the be understood and corrected and the We now use a digitizer that has the program ESCAN was ported from the program to be operational in a very capability to acquire synchronous GTA control system to the discharge short time. waveforms. This digitizer was installed test stand (DTS) control system. This and a software driver was written to brought all the emittunce scanning Automatic rf Structure Conditioning capture waveforms of various accelera- programs to one method allowing for tor signals at a sample rate of 5 MHz more meaningful comparison. We implemented a software tool to with 12-bit resolution. The entire provide automatic rf conditioning of the macropulse can be captured, and up to Phase Scan RFQ, our first attempt at automated approximately 80 contiguous conditioning for any GTA cavity. The macropuLses can be buffered in the IOC. The phase scan program that we began tool was partially tested during the last Four channels are captured simulta- testing last year was brought to the beam experiment, but a complete test neously and time-stamped so they can point of full functionality and maturity requires full access to the RFQ. We be later correlated with other data. The and is robust enough to operate hope this effort will yield information operator can set the number of samples effectively. It does automatic scanning, useful in designing a general code to per waveform, the number of wave- data scaling, data display, and data condition all GTA cavities. forms to acquire, and the trigger timing. storage under operator control. We The operator can also preview the four modified the original design because Video Beam Profiles waveforms on the work station before the rf power occasionally shut down at data is acquired. We used this system zero phase, and a specified time period The video profile diagnostic system during experiment 2A for collecting was required for tlie motorized phase implemented for GTA in FY 1992 was data for beam jitter studies and for shifter to vrork alter a command to shift brought to a fully operational state after studying the performance of rf adaptive phase had been sent. Now the data that several problems were overcome. We feed-forward electronics. an operator sets to configure the scan is discovered there was not enough saved, on a cavity by cavity basis, for a residual gas to produce light, thus gas Off-line Testing default setup the next time the program needed to be injected into the beam is run. This program has produced path. The first attempt at this uncovered We maintained two test stands for essential data for documenting opera- faults in the electronics package that testing accelerator structures before tion of the cavities as well as for initial controlled the injection valve, in the they were installed on the GTA. A low- tuning of the cavities. software that controlled that valve, and power cryogenic test bed and a similar in the hardware that delivered the gas. facility for high-power testing have Steering Modifications were made and the been instrumented with controls system became operational. Initially, equipment to duplicate beam-line AT-8 built a beam-steering software only the system designer could operate conditions. Besides providing data on tool that will aid us in our studies of the diagnostic. However, we modified the behavior and operation of the beam launching into the first DTL tank. the software interface to become more devices under test, we developed and This tool provides the beam with a user friendly, and now this diagnostic is tested control algorithms before target at the DTL entrance; the target a production tool that can be used by installing them in the GTA control consists of position and angle in x any GTA operator. system. and y. This beam-steering tool has yet to be used on-line because of inconsis- Another problem encountered was the Commissioning and tencies with calibration data from the early images captured by the video Automation Software Tools IMS microstrip probes that provide profile showed background that ex- data to the steering tool. The steering tended beyond the edges of the actual Several tools that have specific roles in tool for LEBT steering, previously viewing area. We used several methods the commissioning of the accelerator reported, uses a similar philosophy of to eliminate this background. We were either implemented this year or steering to a target. We dramatically reduced the intensifier gain and inte- were considerably changed from last modified that code because the LEBT grated over only the time when beam is year. These include programs for phase had been shortened. Lambertson present to reduce the background to an scan, for steering in the low-energy magnets now located inside the acceptable level. A cr.-ss section of the bt-u.n transport (LEBT) and IMS. and solenoids are employed to do the remaining image was modeled by a for automating rf cavity conditioning. si.ut.ring. However, inconsi.iient linear combination of two Gaussian A program was also developed that experimental data obtained from functions. The narrower function was recorded beam position data and emittance scanners in the LEBT have the image from the beam interaction, transferred it across the network to a prohibited this program from therefore, we calculated centroids and 88 Accelerator Technology Division Technical Hiahliftlux • AT-fi • Accelerator Controls ami Automation widths from that information while the address the problem. The system is dimensional sieering-quadrupole wider function compensated for the robust to problems with the thermo- positioning. DTL module I also background. This calculation was couples, the errors in the Allen-Bradley implements five step motors for three- incorporated into the real-time imaging computer interface, and in an automatic dimensional positioning of the entire software and displayed as the images to manual mode change. The ion source module. We decided to upgrade the were obtained. is maintained at operational because of control system for the High-Power the system's sensitivity to these condi- Cryogenic Test Bed (HPCTB), to a Presentations were made on this tions and the controller's reaction to the system that could be capable of high- diagnostic at both the Neutral Particle problems. power rf conditioning of DTL modules. Beam (NPB) Symposium at Argonne This modification, in conjunction with and the LINAC Conference at Ottawa. During FY 1992 we presented our work required safety enhancements, necessi- These presentations covered both the on automation to an industrial workshop tated a complete revamping of control implementation system and data organize^ hy SDIO, at the NPB Sympo- wiring and electronics. Another IOC analysis methods. sium at Argonne, at the LINAC Confer- and associated controls were fabricated ence in Ottawa, and we published our and integrated for use with the Low- Ion Source Automation work in Nuclear Instruments and Power Cryogenic Test Bed (LPCTB). Methods. In FY 1992, AT-8 demonstrated a Before experiment 2A, the beamline neural-network based automated ion- Control System Hardware controls for DTL module I were source tuner could control the small- fabricated. Wiring to the beamline was angle source on the Discharge Test Operational Support installed and tested, and a new DTL IOC Stand. This work has since been was implemented on the classified transferred to the GTA injector control Final checkout and integration of all control network. After DTL positioning system. Although the problem of beam experiment 1C controls were in tests, we determined that larger step automating this source is quite similar to progress at the beginning of FY 1992. motors with linear variable differential the work done ' P the DTS, there are During the early stages of the experi- transducer (LVDT) positional feedback major differences. First, the dimension- ment, it became clear that additional would be required for adequate DTL ality of the problem is increased because controls and monitors were necessary position control. Consequently, we there are more adjustable parameters for several components of the IMS. We installed and tested additional hardware. that must be addressed on the 4X source designed additional hardware for the rf- used on GTA. Second, the increased drive-loop elbows to maintain the For experiment 2A, both DTL module 1 mass of the GTA source requires more temperatures and to prevent rf field and the D-l diagnostic plate were heat for proper arc operation than did breakdown, for the frequency tuner step- installed in the first of two DTL vacuum the SAS source. In fact, the heaters motors to prevent binding at cryogenic vessels. A rack of equipment with its provided on the 4X source are insuffi- temperature, and for the upstream associated cabling was installed to cient to bring the anode and cathode to steering quadrupole motors to facilitate control the various valves, pumps, and proper operating temperature, so the operation within acceptable limits. The monitors for this new vacuum system. extra heat required must be provided by original drive motor on the D-plate The new controls were interfaced to the the arc itself. Therefore, the control of bending magnet was found to be existing vacuum control IOC. the temperatures of the anode and marginal in torque; therefore, controls cathode must follow a different strategy. for a larger motor were added. The Because high-beam energies and Third, to move the ion-source controller control room timing system, which currents were associated with experi- from a demonstration mode to an provided key timing signals for control ment 2D, we used sophisticated beam- operational mode requires manual room data acquisition, and the IMS loss monitoring electronics to determine operation. When the controller is video profile system were integrated and when beam was spilled. A new IOC operational it must operate unattended became solid operational tools. was assembled to interface with proto- and therefore must be robust. However, type beam-loss electronics so that it we have resolved all problems identified To prepare for experiment 2A and future could be functionally tesled during while using the controller in the DTS experiments, we implemented two test experiment 2A. The new IOC contains demonstration. For example, if a beds so that each of the ten DTL approximately 100 channels of binary thermocouple indicates an impossible modules could be characterized, rf- and analog inputs and outputs us well as temperature, the controller reacts by conditioned. and functionally tested time-stamp generation, triggering, and taking the loop off-line but maintains before installation on the beamline. fast-protect signals. A large database, the heater set-point. This open-loop Each DTL module contained 34 several sequence programs, and control mode of operation can continue for a temperature monitors, 2 rf frequency screens were also implemented to short time allowing the operator to tuners, and 2 step motors for two- support this effort. Accelerator Technology Division Technical Highlights • AT-8 • Accelerator Controls and Automation Several modifications to the versa- used to perform a series of functional Step-Motor Control module European (VME) time-stamp tests of the entire Fast-Protect System. generation modules were made after Each slave module can be monitored by AT-8 incorporated a convenient scheme experiment 1C for compliance with the control system to determine the design into the existing motor driver new low-level rf timing requirements status of its inputs. Versions of the backplane electronics for controlling for experiments 2A. The new time- slave module were designed in a VME brakes on step motor assemblies (e.g., stamping hardware was fabricated and package for beam-loss applications and the offset bee mline harp assemblies and installed in all eight GTA IOCs that in a VME External Interface (VXI) high-energy beam transport [HEBT] incorporated hardware-generated time package for rf applications. Fast-Protect variable-field quadrupoles). stamps and performed as required Warning Modules were also designed during the experiment. and built for use with the beam-loss A new version or the motor driver monitor electronics to alert operators backplane has been designed to support Fast-Protect System Development when the amount of spilled beam was four motors with incremental encoders. approaching the level at which the beam This version will be required for HEBT To protect accelerator components at would be truncated. Software drivers motor control. A compatible VME higher beam energies, we implemented for each of these devices were written, transition board has also been designed. a fast-reacting hardware fault detection and the entire ^ stem was demonsi-ated system for experiment 2A that can successfully on experiment 2A. Transient Digitizer truncate a beam pulse within microsec- onds of a fault. The hardware designed Optically Isolated Binary Output Transient digitizers with analog band- for this system included several new Module widths of up to 10 MHz are needed and modules. The Fast-Protect Master the demand is expected to increase for module ?Fig. 7.1) generates a carrier Some GTA injector reliability problems experiment 2D. Currently, only the signal mat is daisy chained to a series persisted as a result of electro-magnetic Joerger model VTR-1 transient record- of slave modules. Any slave module interference noise-induced failures of ers, have been used routinely on GTA, receiving a fault input will not pass the the Allen-Bradley modules used to and the 8-bit resolution of these units is carrier signal, thereby breaking the control the high-voltage dome electron- not sufficient for several applications, chain. At the end of the chain is the ics. We determined that the Allen- including beam jitter and rf feed- Extractor Gate Interface Chassis. The Bradley contact output modules (Model forward control studies. This year chassis has inputs from the Personnel OW) were the most likely cause of the Omnibyte, Inc. began manufacturing a Safety System, the Run-Permit System, problem. Consequently, replacement four-channel, 5 MS/s, 12-bit module and the Shift Supervisor Key as well as modules with high-electrical isolation designed by FERMI Laboratory for a from Fast-Protect. Inputs from any of were designed, built, and installed. No very attractive price. We purchased and these systems can terminate the GTA further reliability problems associated evaluated one of these modules and beam. Under program control, the with injector controls were encountered. concluded that although it suffers from Fast-Protect Master module can be digital noise pickup in the board's analog front end, which limits usable resolution to about 10 bits, the module was found to be an attractive alternative to the VTR-1 in most respects, including a much lower cost per-channel. Next Generation Computer for IOCS The Motorola MVME-167 central processing unit module was evaluated as an alternative for the aging Heurtkon HKV2FA units we presently use. The 167 incorporates many important advantages including a 68040 processor, on-board ethemet interface, less heat susceptibility and larger EPROM and RAM capacity. The 167 processor runs control applications at 6 to 10 times the speed of the HKV2FA and costs about Fig. 7.1. Fast-Protect System. 25% less to field in a typical application. 90 Accelerator Technology Division Technical Highlights • AT-8 • Accelerator Controls and Automation We purchased the support software for VXI mechanical module templates were and with the Laboratory's Integrated this new board and converted four test developed in Autocad to aid in the Computing Network (ICN). Open IOCs to use the 167 so that future documentation of each type. standards—TCP/IP, DECNET, X- control system applications can be Windows, NFS, NIS, and DNS for developed and tested vith the 167 We increased our extensive, customized example—are used when possible. As instead of the HKV2FA. parts library for printed circuit board in the past, the reliability of the design and our documentation for a network and availability of central Binary Output variety of parts. This customized parts services has steadily improved, library ensures consistency in design consequently, AT-Division network is The Xycom XY240 VME binary output among many ECAD designers and a model for others in the Laboratory. module was thoroughly evaluated as a supplies useful and relevant information possible replacement for the XY220. for the parts list extraction process. Parts During FY 1992, a major effort was The 240 was found to be a superior lists extracted from each design include a made to consolidate computer services module and a recommended replace- parts description, reference designation, for the VAX computers and Sun ment for future applications. We wrote manufacturer's part number, and workstations, resulting in reduced costs a software driver to allow this module to manufacturer's name. for support and maintenance, improved be incorporated into the EPICS control reliability, and increased performance. system. Computing Support For instance, the original 6 VAX clusters with 28 VAX computers were Nonvolatile IOC Memory Module The AT Division computing network consolidated into 3 clusters and 17 supports exceptionally diverse computer computers, resulting in an annual A Force RR-2 VME memory module equipment and applications. AT-8's savings of approximately $50K in was fitted with 2 MB of SRAM and an computing support section is responsible hardware maintenance, while maintain- onboard battery for backup. A file for operating and maintaining the ing the same computer power. Similar system was created and the board was division's network. Using modern, but upgrades to the Sun file servers on the configured as a RAM disk. Such a proven technology, this section strives to open network resulted in comparable configuration may be used for future maintain high-quality network services savings. We also added mail service applications that require a completely in a heterogeneous computing environ- and central file backup capability to the self-contained IOC running with no ment containing over 150 work stations, personal computers. network resources or with operating over 150 personal computers (IBM and parameters that must be maintained even Macintosh), approximately 20 VAX AT-8's computing support section if there is a power outage. computers, and several network file surveyed the division members to servers. The services range across two .'etermine the requirements for data- Electronic Computer Aided open, unclassified networks and two base management. From this survey, Design (ECAD) Support classified networks. Extensive network we determined that a client/server equipment, including bridges, routers, model relational database management The Electronic Computer Aided Design and terminal servers, are used throughout system (RDBMS) would meet the (ECAD) effort included supporting AT- the network, and network statistics are division's requirements. We evaluated 3's diagnostics design requirements, collected at a central location. The potential commercial RDBMS and AT-5's low-level and high-power rf computing support section is also made preliminary recommendations to design requirements, and AT-8's responsible for complying with various the division. controls hardware development require- Laboratory and Department of Energy ments. Most of this support effort was policies and orders for open and classi- directed toward designing printed circuit fied computing. boards and associated hardware to meet these requirements. In FY 1992, we AT Division networks support a wide placed 80 printed circuit board fabrica- spectrum of scientific computing, tion orders, amounting to more than 850 including measurement and control boards delivered. systems, software development, me- chanical computer aided design (CAD), ECAD also increased design efforts in electronic CAD, experimental data the area of mechanical packaging and reduction, and system modeling. documentation. This included the layout Resources such as printeis and plotters and design of low-level VME Extended are shared among users, anc". the elec- INterface, (VXD printed circuit board tronic mail services for all computers are module, and submodule assemblies. integrated throughout the open network Accelerator Technology Division 91 Technical Hi; tilialus • AT-9 • Very High-Hower Microwave Sources and Effects Introduction 93 Background 93 Microwave Source Development 93 Relalivistic Klystron Amplifier 93 Large Orbit Gxrotron 96 Piezoelectric Experiments 100 Pulsed-Power Research and Development 102 BANSHEE 102 Portable Pulser 103 WEMPE4 103 Electron-Gun Test Stand 103 Vulnerability, Lethality, and Effects (VLE ) Testing 103 High-Level Testing of Mobile Military Systems 103 Test Point Impedance Assessment 104 High-Performance Ground Penetrating Radar (H1PERGPR) 105 Materials Processing with HIGH- POWER MICROWAVES (HPM) .... 106 Wideband Antenna Development 106 1300-MHz RE for the Advanced Free-Electron Laser 106 '•'- \i i rlernini /n lmolt>\i\ DniMn Technical Hi\>hlii;lils • AT-V • Very Hii-h-Pouer Microwave Sources and Effects Introduction Fiscal year 1992 has been successful The military requirement for HPM for AT-9. One of our teams received remains strong even after the recent AT-1) is the Very High-Power Micro- the Laboratory's Distinguished changes in the world military picture. wave Sources and Effects Group within Performance award for experimentally Sophisticated, sensitive electronics are Los Alamos National Laboratory testing and demonstrating a single-shot pervasive on the modern battlefield. (LAND. The group's mission is to microwave-source concept in record HPM has a role in the give-and-take develop new high-power microwave lime. We have made substantial between these electronics And the (HPM) generators and apply them to progress on both the large-orbit countermeasures employed against Department of Energy (DOE) and gyroklystron and relativistic klystron them. The defense requirements for Department of Defense (DoD) prob- amplifier (RKA) projects, with 400- HPM sources encompass the NLC lems. The AT-9 efforts span the range MW output power measured in the needs, but are more diverse. Some from studying the basic physics of RKA work. AT-9 has worked to get defense applications are single shot, high-current electron beam propagation the Advanced Free-Electron Laser others are tunable, while others may be 10 the application of HPM to industry. (AFEL) on the air and has performed transient, wideband pulses. AT-9 is The common theme among these extensive Vulnerability. Lethality, and currently investigating the LOG and the projects is very high-peak power Effects (VLE> testing; new initiatives RKA. Each source concept has microwave radiation. These high peak have begun on both defense and strengths that make it useful for both powers lead to interesting physics as industrial projects. Funding for AT-9 scientific and military application. well as to challenging engineering in activities is supplied by a variety of most of our work. The group's projects DOE and DoD sponsors. Within the Relativistic Klystron Amplifier are divided into two broad categories DOE, our funding supports science with some overlap: microwave source (large-orbit gyrotron [LOG] and Los Alamos is developing an L-band technology development and micro- RKA), hardness testing, cleanup high-current RKA. Although present wave source technology application. (ground penetrating radar (GPR) and experiments are single pulse, the long- Major application.; for HPM are microwave coal benefieiation), and term goal is to achieve 1 kJ/pulse with defense (electromagnetic countermea- participation in the AFEL. The DoD repetitive pulse capability at a repeti- suresh radio frequency sources for sponsors include the Army, Air Force tion rate of 5 Hz with a longer-term particle accelerators such as the and Navy. goal of 100 Hz. The RKA has an input proposed Next Linear Collider (NLC). cavity, a single idler cavity, and an advanced radar, and industrial uses Microwave Source output cavity (Fig. 8.1). The buncher such as coal processing to minimize Development section, which consists of the input and waste products. idler cavities, has been experimentally The NLC is a proposed linear accelera- tested and is performing as designed. Background tor that is to be bui' liter the Super- We designed the buncher section by conducting Super Collider (SSC) is using particle-in-cell (PIC) code AT-9 was originally founded to completed. This machine will allow calculations with the Los Alamos code investigate the defense implications and energetic electron collisions to be ISIS. PIC code modeling has proved to applications of HPM and transient- studied at much higher energies than be very important for successful design pulse technology. From its inception, currently possible at Stanford Linear because of the highly nonlinear nature our group has had a two-pronged Collider (SLC) and LEP at CERN. The of the RKA caused by the intense approach of investigating how to accelerator will require many giga- space-charge effects. The r_.;«i recent produce HPM with our microwave- vvatls of peak microwave power to efforts involved adding the output source development work, as well as accelerate the particles. To minimize cavity to the tube and experimentally how to apply HPM technology. The cost, the rf power sources musl be of optimizing the output power and pulse applied work began with electronics very high peak power with high fre- length to reach the design goal of I k.l/ vulnerability testing to quantify quency (1-20 GHz) and high reliabil- pulse. A number of expected problems susceptibility against microwave ity. These ambitious goals require thai have been encountered with the radiation. This has evolved into an major advances in microwave tube output cavity are being systematically extensive lesi program, both at LANL technology ranging from the electron addressed. Problems include if and at large transient electromagnetic gun and cathode ... to the optics of breakdown in the cavity and the ability simulation facilities elsewhere. AT-9 intense space-charged beams ... to the to match the beam impedance to cavity has been involved in transient-pulse nonlinear interactions involved in gap shunt impedance for the most technology as well, developing bunching the beam, to the high-power efficient conversion of beam power to transmitters, antennas, and diagnostics output couplers and windows. microwave radiation. that have been used for radar and vulnerability testing. Accelerator Tcclmoloi'y Division Technical Highlights • AT-9 * Wry High-Power Microwan Sources and Effects The electron beam is formed from a line. The coax tapers out into standard matched, and most of the magnetron 6.2-cm-diameter annular field-emission 6 inch 50 line in which power is drive power is absorbed and transferred cathode and is slightly compressed by a measured with a directional coupler to modulate the beam. We confirmed converging 0.5 T axial magnetic field and then dissipated in a dummy load. the low reflection with beam loading by to a nominally 5»-cm-diameler beam computer modeling. The comparison with a j-miti thickness. The typical The input cavity was changed from a between theory and experiment is quite beam voltage is 620 kV with an loop coupling design in the original good and is shown in Fig. 8.3. increasing current of 3-6 kA. The input RKA to a waveguide input with iris and idler cavities are quarter-wave coupling to accommodate the increase According to PIC code calculations, the ctxixial resonators. The input cavity is in drive power from 5 kW to a maxi- amount of current modulation produced .-ounk-d le a 300-kW L-hand magne- mum of 300 kW (Fig. 8.2). by the input cavity, necessary for full- tron ,'hrough an iris into a tapered, power output of the tube, was about reduc .'d-height \VR-o50 waveguide. The coupling iris is large enough for 10%. As shown in Fig. 8.4, the input Tne idler cavity has an annular tuning the input cavity to behave as a matched cavity is easily capable of producing ring wviieh gives flexibility in induc- load when the beam is present in the lO'/r modulation with only 200 kW of tively tuning the cavity. The output gap. Consequently, the cavity is very injected rf power. cavity, a noseless pillbox resonator mismatched and reflects most of the with an annular coupling slot near the incident rf power before the beam outer diameter, couples power into a current turns on. Then as the beam low-impedance coaxial transmission traverses the gap, the cavity is nearly RF Input anode tuning slugs dir. coupler 50 ohm coax electron beam cathode load input idler cavity cavity output cavity iY /. Schematic drawing ofrelativistic klystron amplifiei. c 05 1 1 5 2 25 3 35 4 45 5 80- 60- 40- rellec t 20- Powe r 0- ——1—T— 005 1 1522533 5 Fig. iS'..i. Thi'inTiit nl I loner) and experimental power re/let led at the input cavilw S.2. RKA input cavit\' desiifn Accelerator Tcchnotogs Division Technical Highlights • AT-9 • Very High-Power Microwave Sources and Effects 07-ldlar Cav. El-dot A We modified the original RK.A idler 01-PSI Voltage Monitor cavity to include a tuning ring so the 3.0E5 cavity could be inductively tuned (the W cavity's resonant frequency is higher a t than the modulation frequency). This t allowed for greater beam current modulation at the output of the idler cavity for the same amount of bunched beam at the input. Once the cavity was installed on the beamline, data were 13-Coax Coupler (Fwd) 18-Magnetron Pwr (Rev) taken for different tuning frequencies and input cavity drive powers to find W 60000 - : j the best combination for maximum a i t 40000 - -j/- i 1 beam modulation. Figure 8.5 shows the t good input match during the pulse, as 8 20000 - i .V_J well as an output power of more than 100 MW. -2000 - Using PIC code simulations, we Fig. 8.5. Data for Shot #1196 showing good match of input, as well as > 100-MW output power. determined the maximum output of modulated current from the idler cavity Power from the initial output cavity After a number of shots at three to be 65% to 75%. Figure 8.5 shows design was significantly less than different input power settings, no the good input match during the pulse, expected. One difficulty with the consistent rf output pulses were seen. as well as an output power of more than modeling was that a 2D code was used Upon disassembly, the cavity was found 100 MW. The average beam modula- to calculate the interaction, which does to be arcing at the vanes used to adjust tion is near 66% over the pulse length. not realistically model the three the coupling. Once most of the vanes The amount of extractable beam power dimensional geometry of the actual were machined away, the first sign of is usually given as P = (VM,)/-?. For experiment. Even though the designed linear operation started to appear. For 5 this case, about 1 GW of extractable Q of the cavity was 10, the measured kW of injected rf power, output power energy is available at the fundamental cavity Q was approximately 200 and was an average 6 MW. For 20 kW of frequency. The output cavity should be therefore could not be tuned on injected power, output power was an at least 70% efficient and should resonance for maximum efficiency average of 25 MW. In addition, the rf produce 700 MW of rf power out or without producing electric fields that pulse length increased to over a 700 J per pulse. exceeded the level for rf breakdown. microsecond, which was our goal. IH A new section of the output cavity has been built based on cold tests that give SB y^ the desired loaded Q of -10. The much 12- lower loaded Q results in much lower - El electric fields across the cavity gap 10- B B B thereby mitigating the breakdown El problem. This change creates a better 8- B**S B match between the beam impedance and B the cavity shunt impedance resulting in B B 6- EB maximum conversion efficiency from beam power to microwave power. B J& 4- EP B Injection powers of 6, 20, and 90 kW 2- have been tried with some success. At the lower injection powers, the RKA was showing approximately 30 decibel °0 iod 2od 300I (dB) of gain, giving output powers of 6 and20MW, respectively. With 90 kW Magnetron Power (kW) of injected power, the RKA appears to have four distinct modes of operation. Fig N.4. Current modulation downstream of input cavity as a function of if input power. Accelerator Technology Division 95 Technical HI'.I;/I/I,V/IK • .-17'-^ • Wry Hiah-Power Microwave Source* ami Effects The first mode IS one in which not In the second mode, the idler cavity power ranges from 200 lo 300 MW much power is produced even though shows reasonable modulation at the over the ramp-shaped pulse with peak most of the waveforms are essentially very beginning, but then falls off power levels as high as 400 MW. good. The idler cavity signal is taken abruptly after about 300 us. This The gain in this nunu. ..•> aowui 3d ilB. lYom a B-dot in the cav ity. As can he waveform usually correlates with the In the main part o\' the pulse, there are seen in Fig. K.o, the cavity signal stays beam voltage changes at the beginning II0J of rl energy. at a relatively low value throughout the of electron emission from the cathode, pulse tor no apparent reason. Output but an initial bump in the beam voltage If the fourth mode could he chosen power is usually in the range of 21) to does not always produce the same selectively, the breakdown might be 40 M\V for 0.5 us. problem in the idler. Output power solved by lowering further the output typically spikes to cavily Q. thus reducing the gap fields about 20 to 50 MVV. and also modifying ihe idler cavity to 01-PSI Voltage Monitor handle higher fields without breaking The third mode con- down. However, only the third mode 8.0E5 sists of the idler cavity gives output powers that are consis- modulating well for the tent with ihe gains measured al low V 6 0E5 first half of the pulse, power injections. Solving this prob- o but then something lem is difficult, because there arc no I seems to change the daia to correlate directly with the t 4 OES beam modulation at the problem to date. The breakdown s input cavily. This, in could be a result of the changing 2.0E5 - turn, causes a change beam voltage affecting the way the A in the input cavity input cavity bunches. Alternatively, 0.0E0 ~r match ami increases higher beam harmonics could be 0 the amount of reflected propagating up the beam pipe creating injection power. With the mismatch in the input cavity. the drive power to the 07-ldler Cav. B-dot A input cavity dropping, Uirf-e Orbit (iyrolron the desired beam 100 - modulation also drops We have designed and are testing a I I off and drops the out- I.OCi amplifier for 1.3 GHz operation 8 0 W put power. Often, the in fi5 us pulses. The ultimate power a i it beginning of the idler t 60 output goal is 500 MW with a gain of t ' iri cavily drop correlates at least 20 ilB. This initial investigation 4 0 .. . s ; i with the beginning of is intended lo lay the groundwork for the beam voltage's de- operation at I 1.4 Gil/, for particle 20 scent. Output power is accelerator applications and also al reasonable in these 0 - frequencies of up to 35 (ill/ for other shots and very often uses. Computational design has been from SO to 130 MW per'.Mined with the resonant cavity for 0.5 us. code MAFIA and the IMC codes MF.UUN and ISIS, i:\periniental 13-Coax Coupler (Fwd) In the fourth and final measurements of the resonator modes were correlated w iih computational and 5.0E8 -I mode, ihe idler cavity works well. The out- analytical predictions. We studied and experimentally verified electron-beam w 4. 0E8 put power climbs lo the a point where the output optics through a magnetic cusp with t 3. 0E8 cavily gap field is high ISIS and MliRI.IN to develop a t enough lo reflect elec- suitable electron-beam trajectory from s 2. OE8 trons back up stream. Ihe electron gun into the microwave resonator region. Performance tests 1. OES Consequently, the idler cavilv breaks down and have begun. In its final form, ihe .—I 0. 0E0 ends the pulse, usually device will use two resonators sepa- only 350 us I mm the rated bv an electron-beam drift lube. initial siari. Average h'i ffl I4t>. \lin\i mi; i>uli .•\ccflrrator Division Technical Highlights • AT-9 • Very High-Power Microwave Sources and Effects A LOG amplifier operating at 1.3 GHz We used two loops, one in each of the azimuthal beam bunching. To extract is being developed to operate at powers two vanes, to feed rf into the cavity. If energy, a second output resonator de- of up to 500 MW for 65 ns pulses. the beam's angular velocity is synchro- signed to be strongly coupled to the While this initial investigation is being nized, the cavity's standing wave pat- beam will be placed downstream of the performed at 1.3 GHz, this amplifier tern will couple to the rotating beam drift pipe at the point of optimum beam can be scaled to higher frequencies in a provided. Consequently, an azimuthal bunching. Mode converters suitable for straightforward fashion. LOG oscilla- density perturbation will grow on the transforming the TE0! circular tors have operated at 15 GHz and beam with three-density maxima waveguide mode of the output resona- higher frequencies with comparable around the azimuth. The magnitude of tor into TE10 rectangular waveguide performance at lower frequencies. the density variation will grow as the mode have been thoroughly studied Amplifier operation has been examined beam propagates down the resonator's since the 1950s. theoretically and experimentally, but length, influenced by the applied oscil- less extensively. lating rf fields and the space-charge We designed the electron gun and self-fields that drive the negative mass optimized the electron beam trajectory These LOG amplifiers produce micro- instability. The instability will grow as using the two-dimensional versions of waves when a helically rotating electron the electron beam propagates through ISIS and MERLIN PIC codes. • Pre- beam interacts with the oscillating fields the system. Feedback from the beam liminary studies were performed with a of u resonant cavity structure. The elec- instability drives the cavity fields to computational technique known as tron beam is formed by injecting a hol- greater amplitude. synthesis. This technique steps the low, nonrotating beam, born in an axial particles backward in position and time magnetic field, through a magnetic cusp The first cavity's downstream end has a from the final state, (i.e., beam current, positioned at the anode plane. The central opening that forms the entrance position, and velocity components). gyrotron radius of the electron is equal to a cylindrical, nonvaned electron- The initial conditions (i.e., emission- to the radius of the annular beam, so this beam drift pipe. The pipe isolates the electrode position, shape, and potential) device is referred to as "large-orbit," as rf radiation between the first and sec- that lead to the final state, and a opposed to a conventional gyrotron in ond cavities and serves as a region satisfactory trajectory through the which the orbits may be very small be- where the beam bunching can grow by device can be determined. cause of a relatively high magnetic field. the negative mass instability, indepen- An annular slot is cut into the iron cusp dent of applied microwave fields. An plate to allow the beam to pass into the optimum drift pipe length will be deter- downstream resonator. In the cusp, a mined experimentally to maximize portion of the axial beam energy is con- verted to rotational energy. Typical ra- .!os of rotational velocity to axial veloc- Single Cavity Version ity (defined as CC) are in the range of Ends Here Negative Field 1.5 to 2.5. The electron beam entering Shaping Electrode Helmholtz Coils the resonator has an energy of 500 to Drift Sever 700 keV. a current of 1 to 3 kA, and a Solenoid radius of 5 to 8 cm. The device, shown in Fig. 8.7. employs a cylindrical reso- Input Cavity nator with three vanes in the wall spaced End View equally in azimuth. The amplifier is designed to have two cylindrical resonators as described above. The vane structure is used to evoke coupling of the rotating electron beam with the transverse electric RF Input Loop TE(0.1 .n | resonant cavity mode of the Helical cylindrical structure by modifying the Electron Beam normalK circular electric field pattern of Dielectric Window the mode into a scalloped pattern, simi- Knife Edge or Voltays Monitor Velvet Emitter lar to the TE(3.1.n) mode but near the Cusp Current Monitors lower TE(O.l.n) resonant frequency for a nonvaned cylindrical wall with an in- termediate radius. f-ig. X.,'. Schematic drawing ujlarge-orbit t-yrnklxsiron amplifier. Accelerator Technology Division 97 Technical Highlights • AT-9 • Very High-Power Microwave Sources ami Effects An acceptable synthetically generated geometry is shown in diode configuration consists of a Fig. 8.9. Electron cathode-emission annulus with a emission was produced diameter of 14 to 14.2 cm or a conical from an annular region Resonator equipotential surface at an angle of of the angled surface 67.5° with respect to the symmetry axis either by mounting a (Fig. 8.8). The distance between the knife-edged ring or a emission annulus and the anode was 2.2 velvet belt on the cm, yielding a cathode electric field of surface as an explosive 300 kV/cnTat a voltage of 650 kV. The emission cathode. The annular opening at the anode through emitting ring's diameter which the beam passes into the resona- varied from 11.4 to 14 tor drift section has a mean diameter of cm. The drift pipe had 12.5 cm and a width of 1 cm. no vane structure for these diode experi- We began with a synthetic computation ments, to approximate that was the starting point to conven- the conditions of the tionally calculate beam dynamics computer model. moving forward in time. A conven- tional run using the diode and drift-pipe Alpha, (a) was mea- Election Beam parameters from the synthetic calcula- sured using a quartz tions agreed with the synthetic calcula- witness plate placed in Anode (Cusp Region) tion prediction. All of the current the beam path. The emitted from the cathode, up to a quartz's luminosity Cathode Emitter maximum of 2.7 kA passed through the permits a pattern of the cusp and drifted with little radial electron deposition to Fig. 8.9. Three-dimensional ISIS calculation of oscillation while in the resonator region. be seen at the plate electron trajectories including dc and ac fields. location. A shadow is We built the diode hardware using PIC cast on the quartz when modeling: the experimental diode a metal rectangle is attached upright on the upstream side of the quartz at the radius of the beam The ratio of the 45.0 length of the shadow to the height of the obstruction is a measurement of a. Anode Magnetic Cusp . Alpha was measured to be in the range of 1.5 to 2.0 for a magnetic field of JU.7 - 400 G and in the range of 2,0 to 2.5 with a magnetic field strength of 500 G. This alpha range most accurately matched that shown by the computer model as providing good beam transport. We transported 3 kA past the cusp with B . Cathode an alpha of 1.5 using a knife-edge to !• I. emitter with a diameter of 12.4 cm, a 1 (' ; magnetic field of 300 to 400 G and a 11 _J - diode voltage of 700 kV. Waveforms ,..- Gyrotron RF Source for this case are shown in Fig. 8.10. These lower magnetic field conditions are those anticipated for the 1.3 GHz Slot Electron Beam amplifier experiments. The computer study did not include these parameters 5.0 20.0 12.5 in its investigation, but rather used Axial Distance (cm) magnetic field of 500 G at the cathode, based upon the needs of an amplifier designed for higher frequency. Fig. Election gun and beam optics synthesized using com/niter modeling. 98 Accelerator Technology Division Technical Highlights • AT-9 • Very High-Power Microwave Sources and Effects We conducted an extensive study of • : ; i-^/^. 4 4 •= 10.0- ?o.o- : the resonant structure's cavity modes \ /!T...(\/>^W/^A- i if ••%-Diodc C"urrcrit ""I jf : v 5 : : using the electromagnetic field- \ I l • solving code MAFIA, analytic ...A. "J \ Diode Voltage [ 00 J ^J..l K. -A--ij/\- Voltag e JC7...| 1 .! j j modeling, and cold-test measurements § -A : i : i : i i' ' I" performed with a vector network 0 200 400 200 400 analyzer. Figure 8.11 shows the Time (ns) Time (ns) frequencies measured with a network analyzer connected to magnetic loop 30 (" TV- Gyrotron Inpuf'1 probes in the cavity, oriented to couple I : l-fjir iCurxcnt . -H to the TE(O,l,n) modes. The peak of c ;• Gyrotron Exit Current o interest, the TE(0,1,0.5) mode, = 0.0- oscillates at 1,280 Hz. Figure 8.1? shows the MAFIA calculated electric- 200 400 200 400 field pattern for this mode at 1277 Time (ns) Time (ns) MHz, showing good agreement with Fig. 8.10. Beam voltage and current from a typical gyrotron shot. Input beam power to the cold-test measurement. When we gyrotron is 2.4 GW. test the input cavity with the down- stream end fully open, the cavity had a 1.2 Q of 45. As a two-stage device, the first stage Q will be much higher, of the order of several hundred. The output cavity Q of the two-stage 0.9. | device will be similar to that of the h single-stage resonator, in the range of 25 to 100. | 0.6. The experimental configuration / consists of the diode, magnetic field coils, downstream resonator section, and a dielectric vacuum window. The 0.3 . vacuum window is used for radiating 1 the microwaves into an anechoic / volume downstream of the vacuum chamber. A 4-kW 1.3-GHz source 0.0 T— ~ V provides rf input drive to the resonator L 0.3 0.9 1.5 2.1 in these initial studies. Up to 20 MW T 1 is available as input drive, but device Frequency (GigaHertz) modifications are required for aperture Fig. 8.11. Measured mode spectrum of gyrotron resonant structure. The strong peak at coupling to accommodate the power. 1286 MHz is the desired operating point. Presently, magnetic loops are located at the base of two vanes for cavity input drive. A loop in the third vane is used to monitor the cavity's standing- wave field. A stub-waveguide receiver is positioned in the anechoic volume, downstream of the opened a Q « c o end of the resonator to monitor the radiated power. OOOOQOOOGGG o ©©GOOOOOOO G ooooOOQOOO o G o O OOO0QOQ o a o o w O o Fig. 8.12. MAFIA output showing electric field distribution of.i-peld symmetric mode at 1277 MHz. Accelerator Technology Division 99 Technical Hif;hli)(hts • AT-y • Very Hiffh-Pinwr Microwave Sources uiul Effects We evaluate amplifier performance by Piezoelectric Experiments polymer. This newer material is a comparing the radiated microwave flexible, compliant, clear plastic film power m three different circumstances, Compact sources oi high-intensity that can be readily cut, shaped, and bust, the radiated power resulting from electromagnetic radiation offer impor- metali/.ed with a conductive electrode the 4-kW input drive alone is mea- tant advantages in counter-electronic coaling. The properties of interest are sured. Second, we measure the military applications. At DoD's • wide frequency range-near radiated power with no input drive, but request, AT-9 and several other dc to low GHz with the electron beam injected. Laboratory groups developed a new • vast dynamic-range-sensilive to Finally, the radiated power is measured concept and conducted simple, prool- both minute forces and explosive when both input rl drive and injected ol-principle (POP) field experiments shocks (nanohar to megabar) electron beam are present in the for producing a compact source of • high-output voltage-10 times resonator. Relative power measure- intense microwave radiation. These higher than pie/oceramic for the ments among shois are performed by experiments demonstrated thai micro- same input force comparing detected signals received wave radiation is produced from • high-dc dielectric strength-75 with a waveguide stub placed at a fixed piezoelectric material when it is V/um location in the far field downstream of compressed by a high-explosive- • high-mechanical strength and the resonator. generated shock wave. This is the first impact resistance time microwave radiation has been • very low raw material and With nn input drive, the radiated rf produced directly from a high explo- fabrication costs power pulse was narrow m tune. 42-ns sive without the complex, intermediate • reasonable dielectric constant long, with a wide statistical standard stage, which consists of a magnetic flux (relative dielectric constant ~ 12) dev iation of 24 ns or 56'* . This compression-generator power supply enabling a high stored energy duration is significantly less (approxi- that produces a high-intensity electron mately 6.5 ns) than the lull width at half beam, which is subsequently converted One characteristic of a high-explosive maximum (FWHMl duration of the to microwaves. This entire effort from detonation is the intense shock wave electron-beam current in the resonator. concept through explosive testing was that generates very high pressures in In addition, the mean value of the peak conducted in approximately 2 weeks. the 300 to 500 kbar range and as high power, while larger than with input The group received the Laboratory's as I Mbar in a convergent lens system. drive, had a ZS'i standard deviation. Distinguished Performance Award in The high pressure in conjunction with u With input drive, the output power recognition of its efforts. piezoelectric material enables large puke continued for 60 ns. nearly the voltages and currents to be generated. length of the electron beam pulse, w ith Fxplosively-driven microwave and Piezoelectric plastic film can produce a standard dev iati'in of 16 ns or 27'r. ultra wideband generators can produce electric fields of 0.3 V,'m per Pascal. The peak power of the output puke mission kill of electronic equipment at Because 0.1 Mbar(= 10"' Pa) is easily using input drive was 26'v lower than stand-off ranges, preventing blast achievable with a high-explosive without input drive, hut was longer by damage (or combined explosive and detonation, we can generate electric 50'•» with a smaller standard deviation electromagnetic effects at closer ranges, fields of 3 x 10''V/m assuming linear of 16 ns or 2T'i. The FWHM of the if desired I. These systems can be induced voltage vs pressure behavior of fast Fourier transform of the rf signal delivered to close range by existing the material. This is a reasonable was 36 MHz (25 MHz standard missile and artillery systems. Explo- assumption based on the deviation) without input drive and 27 sively-powered devices would enable manufacturer's specifications and on MH/ ( 17 MH/ standard deviation) with much smaller payloads to exist, Sandia's work with piezoelectric input drive. Hence, there was clear requiring much smaller delivery material in an unrelated application. improvement m ihe ouipul power puke systems, thereby allowing a much Klectric fields of, 3 x 10" Win exceed associated with the application of input w ider range of uses. the dc dielectric strength, which is rl drive, as was shown in total energy about 10" V/m. It is well known that as ol the output piike. the frequency A piezoelectric material becomes pulse length decreases the dielectric puniv. and in reduction of the statistical electrically polarized when mechani- breakdown level increases, so that as variation among pukes cally deformed, or it changes dimen- the puke length is reduced from dc to sion when placed in an electric field. fractions of a microsecond, the break- Historically these materials have been down level will increase significantly crystalline such as quart/, or ceramic. above the dc dielectric strength of 10" However, recent developments with V/m. For comparison, the electric field organic polymers have resulted in produced by nuclear electromagnetic materials with far greater pie/o activ its pulse (F.MP) is 10" V/m. The piezo- that anv other synthetic or natural electric material can also he Healed us a I til) i celi'ivlor Ti'chiioliif;\ Dmsiim Technical Highlights • AT-9 • Very High-Power Microwave Sources and Effects current generator. A 1 mnv sample of material's capability to generate a large 600 ns in the detected microwave piezoelectric material has generated 8 A current to drive a loop antenna signals. Figure 8.15 shows data from of current, indicating that if the size designed to resonate at 50 MHz. two different receiving antennas on the were scaled to 7 x 7 cm, more than 5 kA same explosive shot, when we used the could be generated. When scaled to Diagnostics employed at the firing Fig. 8.13 bowtop geometry. We realisti': sizes, these numbers show that point included five antennas covering estimated the radiated power densities piezoelectric material could produce overlapping frequency bands that at the antennas located 40 feet from the electromagnetic pulses that could be ranged from a few megahertz to 12 firing table to be tens of |aW/cm-. radiated and used against a variety of GHz. The antennas included a targets. horizontal longwire doublet, a log Based on all five shots in two vastly periodic antenna (bandwidth = 20 different configurations (three witM the Piezoelectric material is available in MHz to 1 GHz), two ridged waveguide bowtop and two with the loop antenna), films 9 to 800 prn thick with a thin 0.2 horns with different bandwidths (0.5 to these field tests demonstrated •••at jinn aluminum coating sputtered onto 6 GHz and 1.0 to 12.4 GHz), and a D- electromagnetic radiation can be both sides for electrical contact. The dot probe (electrically small dipole). repeated generated by piezoelectric film layers can be stacked so the voltage We observed radiation at frequencies material that is compressed by a high- across one thickness adds to the voltage ranging from a few megahertz to as explosive driven shock wave This of the other thicknesses, such as when high as 0.5 to I GHz when the bowtop microwave source package is relatively capacitors are connected in series. This antenna with a 30 to 700 MHz band- compact and the quantity of high piezoelectric material should be width was used to radiate the pulse. explosive is only a few hundred grams. configured such that an explosive shock We observed rise times of approxi- wave can compress the material, and mately 3 ns and pulse widths as long as with a geometry which allows connec- tion to an antenna. We performed a POP experiment to become more familiar with the concepts that might lend to a useful device. 52 MICRON THICK LAYERS OF METALIZED PIEZO FILM Although performed quickly, simply, \ and with unrefined diagnostics, the POP 30 cm 0 LAYERS OF FILM, 5x5 cm field tests demonstrated conclusively TOTAL THICKNESS = 0.5 mm ..•' that electromagnetic radiation can be generated by piezoelectric material when a high-explosive driven shock wave is used to compress the material. The two configurations shown in Figs. 8.13 and 8.14 were tested at Firing Point 6 in Ancho Canyon in a collaborative DETASHEET HIGH EXPLOSIVE (300 g, 7 cm x 7 cm x 8mm thick) experiment with AT-9 and M-6. the Shock Wave Physics Group: MEE-3. 1,1;. K.I3. Explosively driven rf experimental configuration (Bowtop antenna). MVFSI-M the Instrumentation Group: MEE-9. and the Engineering Design Group. The configuration in Fig. 8.13 illustrates that when we stack the layers of piezoelec- LOOP ANTENNA tric film, voltage is generated across the 38x38 cm layers. A wideband bowtop antenna was used to radiate the energy. Physical dimensions of the film were 5x5 cm: TUNING 10 layers of 52-um thick film were CAPACITOR (-50 MHz) stacked one on top of the other. This configuration used 300 g of Detasheet high explosive in two 4-mm-thiek, 7x7 cm squares. The test configuration 0.5 mm THICKNES shown in Fig. 8.14 u:.ed a single 0.5- 7.5x7.5 cm mm-thick sheet of piezoelectric poly- mer. This configuration uses the Fig. N. 14. Explosively driven if experimental layout (loop antenna). Accelerator Technology Division 10! Technical Highlights • AT-9 * Very High-Power Microwave Sowves anil Effects 0.1 repetitively pulsed HPM sources and for wideband, transient pulse generation. v 0.00 I H V These applications require outputs of 2 -0.1 tens of kilovolts to megavolts into loads o •0.10 of 50 to 100 ohms for nanosecond to t iI * -0.3 microsecond pulse lengths at repetition -0.20 rates up to tens of kilohertz. Most of our Io developmental pulsers employ state-of- -0.5 -0.30 the-art thyratron switches. These tubes 3.4 3.6 3.8 4.0 3.2 3.4 3.6 3.8 are part of a long-term effort at Los Time (us) Time (us) Alamos to develop extremely high- Fig. K. 15. Oetechil output waveforms received m 40 ft from How top antenna: powered repetitive switches for particle (a) receiver passhaiul 20-1000 MHz and (/>) receiver imssbtnitl .5 - 6 GHz. beams and lasers. Although these are our first experi- this project on such a tight time scale, BANSHEE ments and our understanding of the with personnel from five groups across physics and engineering issues in- four technical divisions, required an The RANSHEE pulser cunvmly .=.,: volved is extremely limited, we forsee exemplary level of skill, teamvvork, and supplies a oOvi-kV, 10-kA, 2-jas pulse. It improvements of at least eight orders of dedication by each member well is being used as the electron-beam driver! magnitude in the power levels. beyond normal expectations. for the RKA experiment and as a thyratron test bed (Fig. 8.16). Recently, This team of people developed a Pulsed-Power Research and the CX1812 thyratron tube produced by scientific concept, engineered the Development English Electric Valve (EEV) has been concept, and implemented a proof of tested to failure. Currently, this thyra- principle demonstration in less than 2 AT-9 is actively developing pulsed- tron tube, developed for the Strategic weeks The successful completion of power technology tor advanced, Defense Initiative Organization (SDIO) Fig. 8.16. BANSHEE [miser with RKA experiment in place. 102 Accelerator Technology Division Technical Highlights • AT-Vm Very High-Power Microwave Sources ami Effects applications has the highest peak Electron-Gun Test Stand coupling tests provide AT-9 with the power of any thyratron produced. opportunity to continue to develop Several smaller tubes have been Construction has started on an electron ultrawideband video-pulse sources and qualified at the multigigawatt, micro- gun test stand, a 200-kV, 200-A, 15-Hz to contribute critical coupling data to second level at up to 5 H.'.. EEV has high-vo'tage modulator used for national committees such as the Sys- corrected the flaws discovered in the developing and testing electron-gun tem Effects Assessment Team, the first tests of the CX1812 and has components. We will be able to test Foreign Asset Assessment Team, and produced an improved tube variant that high-current density cathodes and parts the Department Of Energy (DOE) Tri- will be tested in BANSHEE in 1993. of advanced electron guns indepen- Lab High Power Microwave (HPM) The tests to date have reached the dently of the microwave source Vulnerability Committee. During limits of the pulsed-power system in experiments on BANSHEE. FY 1992, the VL&E Section con- several areas. An improved charging ducted electromagnetic-coupling tests system and power supply have been Vulnerability, Lethality, and on three mobile military systems. designed and presented to sponsors. If Effects (VL&E) Testing These tests used a variety of electro- funded, these would allow BANSHEE magnetic environments to ensure com- plete electromagnetic characterization to operate in burst mode at the mega- During the last 3 years, the Vulnerabil- of each system. watt average power level. Improved ity, Lethality, and Effects (VL&E) capacitors have been identified that can Section in AT-9 has conducted many if operate reliably at this average power effects tests, and the quantity of work is High-Level Testing of Mobile Military level. growing every year. This section is Systems responsible for planning, executing, Portable Pulser and documenting electromagnetic- During FY i i>92, AT-9 conducted low- coupling tests for various government level frequency-domain tests on each The portable pulser is another ad- sponsors; data processing and analysis system to build a baseline data set from vanced modulator developed for HPM are an additional charter shared with which the response of the command source experiments. In 1992 this Group X-5. The electromagnetic- post to high-level environments would system was moved into the new AT-9 be predicted. A typical system is laboratory' in building MPF-14, the first shown in Fig. 8.18. The data acquired step in the system's full-power during the high-level electromagnetic commissioning. In 1993 we will add (EM) coupling test were then com- the shielding and diagnostic facilities, pared with the values predicted from and the LOG experiments will be the low-level data to evaluate the accu- transferred to this machine, yielding a racy of numerical techniques used in highly reproducible 600-kV, 3-kA generating the "pre-test prediction" pulse. The system's ability to repro- values. After review of the data, we duce voltage will be a major improve- determined that the numerical tech- ment over the existing gyrotron power niques used to create the predicted source, because the voltage repeatabil- values were valid, and we incorporated ity between shots is critical when both the high- and low-level data into a developing the complex beam optics in transfer function data base. This data the cusp-injected electron gun. base is available to assist weapons designers in their evaluation of WEMPE 4 weapons's output in the context of the electromagnetic frequency coupling A wideband electromagnetic pulse windows on that particular system. The environment (WEMPE 4) was devel- test were conducted at the Defense oped by AT-9 over the past several Nuclear Agency's Advanced Research years for effects testing, developing Electromagnetic Simulator (ARES): a antennas, and developing GPR. A facility originally built to lest ICBM turnkey WEMPE 4 system was systems such as the MINUTEMAN constructed and delivered to the air and the PEACEKEEPER. However, force's Rome Air Development Center recent modifications have given the in 1992, Fig. 8.17. This is a user- facility the capability to conduct both friendly package supplied for wideband low-level frequency domain and low-, EMP experiments. medium-, and high-level time domain Fig. H. 17. Electromagnetic Pulse Generator pulse testing. delivered to Pome Air Development Center. Accelerator Technology Division 103 Technical Highlights • AT-9 • Very High-Power Microwave Sources and Effects Fig. 8. IS. Typical electronic system undergoing F.MP VLE tests. Test Point Impedance (reflected energy) measurements made are measured in parallel. However, Assessment on numerous test points and based on when the system is illuminated in a free the fact that printed circuit designers space EM environment, the coupling While ihe overall lest methodology did use dimensions for the printed circuit path and test point impedance are in not vary from that used in FYIWI. we that correspond to approximately 50 Li series, resulting in a different voltage did use the tests lo complete develop- for frequencies > GHz. However, that and current distribution as compared ment of a simple technique used to value is nol valid because the circuit with the SM measurement. This led us measure the impedance of a lest point components begin to dominate Ihe l'> devise a simple method by which the in .situ. circuit impedance al frequencies < 1 lest engineer could determine the lest Gil/. We believe the Sn technique is point impedance m a realistic measure- In the past, the HPM testing commu- limited to providing insight only into ment situation. nity has used an nominal value ol"50 the trend of the data but not the actual ohms ( Q ) for the test poml impedance. value. During the S measurement. Ihe This choice is heavily derived from S coupling path and test point impedance 104 Accelerator Technology Division Technical Highlights • AT-V • Very High-Power Microwave Sources and Effects Our new technique connects a shunt High-Performance Ground When combined with the proper resistor across the test point to ground. Penetrating Radar radar receiver technology, these The ground point is common to voltage (HIPERGPR) power increases result in the radar probe and the test point circuit. This penetrating much deeper into the creates a three-resistor parallel circuit AT-9's goal is to produce an effective earth. The prototype high perfor- that features two known (voltage probe subsurface radar that has commercial mance ground penetrating radar and shunt resistor) and one unknown value for ongoing environmental (HIPERGPR) has demonstrated ten (test point impedance) resistances. cleanup programs by developing the times greater depth range than a Figure 8.19a shows the equivalent existing prototype at LANL into a commercial GPR when tested at TA- circuit at the test point. This parallel fieldable system with substantially 49. inFY 1992. our efforts with circuit is in series with the coupling higher performance than existing GPR focused on benchmarking the aperture. With different values of the systems. This prototype has four orders device's performance against shunt resistor, we can obtain different of magnitude more peak power and realistic targets as well as improving transfer functions. Figure 8.19b shows five orders of magnitude more average the system's signal processing and three such transfer functions that power than commercial GPR units. user interface. illustrate the change in response caused by the shunt register. By ratioing the The concept ofcradlc-lo-gravc "no shunt" case with the "1000 Q" control of weapons materials puts shunt and the "50 Q." shunt, we can new requirements on defense calculate the actual test point imped- programs (DP) to locate buried ance at each frequency of interest. This waste and to continuously monitor technique is very useful because it is disposal sites. Wideband high-power easy to implement and gives the test pulsers and diagnostics developed engineer an accurate measure of the for the nuclear effects program can effect of instrumentations on the test be used to clean up DOE waste sites point response. effectively, efficiently, and eco- nomically. Hence, the HIPERGPR In FY 1993. four systems will be with its greater search range, can tested, with the first test scheduled to perform noninvasive, subsurface begin in March 1993. The systems will surveys over realistically sized be tested at a variety of simulators burial sites. Additionally, the because of the various requirements of HIPERGPR provides the unique our sponsors. The data acquired in FY additional capability to accurately 1992 will be used to improve the measure the burial depths. extrapolation techniques currently used in scaling low-leve! responses to high- level environments and will become the backbone of system vulnerability I—I—I I I I III 1—I—I I 11II analysis currently underway at Los Alamos. The data will also become an important cross-check for an ongoing EM modeling effort that is studying the n I coupling efficiency of an incident plane ui wave to a complex, lossy cavity. Additional smaller effects tests will be performed in conjunction with the GPR program to continue the development of untrawideband video pulsers and appropriate antennas used to propagate the new wave forms. 1 W o EB.O E7.0 FREQUENCY - HZ h. ( Fig. iS'./ >. Mea.,'trement ofcircnil impedance: (a) circuit model showing added /l( resistor, and tbl measured coupling data showing effect of three different resistance values. Accelerator Technology Division 105 Technical Highlights • AT-9 • Very High-Power Microwave Sources and Effects Materials Processing with routinely in CLS. For the initial ,. rrk, 1300-MHz KF for the High-Power Microwaves we focused on Fourier-transform Advanced Free-Electron Laser (HPM) infrared spectroscopy augmented by mass .spectroscopy. Infrared spectros- The 20-MW, 1300-MHz klystron was The application of high-power micro- copy is the preferred technique for brought back on line to support the waves (HPM) to materials processing is analyzing the hydrocarbon gases AFEL experiment. Many improve- a new project in AT-9 begun in 1992. expected to be evolved from the coal ments were made to the system's Initially, we are researching how samples. An experimental sample housekeeping in the wake of the Tiger microwave radiation interacts with coal collection system was set up in AT-9 as Team visit. After these improvements in a collaboration with the Coal a precursor to the actual microwave were completed, the waveguide was Technology Office at LANL. Further processing, and several samples were reconnected to the compact linac of the work involving microwave chemistry analyzed at CLS-6. The next step is to AFEL and the system was promptly has ah o begun. irradiate coal samples using the 20- conditioned up to the 20-McV level (10 MW, 1300-MHz klystron in building megawatts peak rf power). During 1992 Coal, the most common fossil fuel, MPF-14. A waveguide sample holder klystron personnel worked closely with produces pollution as a byproduct of its has been assembled for this purpose AT-7 personnel to commission the combustion. This major limitation to its and is ready for use. AFEL and diagnose and troubleshoot use has led us to investigate methods of the beamline and subsystems. AT-9 cleaning up the coal fuel cycle. Microwave heating is becoming a worked closely with AT-7 and AT-5 to Beneficiation is the process rjf remov- useful tool of the industrial chemist. implement and test rf control systems ing pollutants before the coal is burned. Many processes are aided by the on the system. The work with AT-5 Typically, less useful constituents such selective and rapid heating produced by was a high-power shakedown test of as sulfur and heavy metals are removed microwaves. AT-9 is looking at the the University of Twente's low-level by a chemical cleansing process. A possible benefits of high-power pulsed control system. This realistic test related technique is coal gasification or microwave energy for chemistry. allowed for many small details to be liquefaction in which the most valuable Many chemical reactions are limited by corrected before the system was constituents are removed from the bulk competing reactions that interfere with shipped to the Netherlands. of the coal leaving less useful and the desired reaction. However, if dirtier components as waste. AT-9 is microwave energy is applied in a AT-9 proposed a design for a compact investigating the interaction of micro- pulsed mode, the desired interaction 1300-MHz rf system intended to be a wave pulses with coal samples in an may be favored so that the overall dedicated klystron stand for the AFEL. experimental effort to understand the system tfficiency is enhanced. This The design is a very compact package flow of microwave energy into the coal has been demonstrated at low-power designed to minimize the AFEL size. It on a short time scale. We believe that levels, and we are trying to employ the will employ a large klystron, the Litton the coal will be heated and fractured high-power sources and expertise in L-3702, several of which are available allowing the volatile constituents to be AT-9 to improve technique. in AT-9. This system will supply a released und separated. longer pulse with higher peak power, as Wideband Antenna well as higher average power than the Our experimental investigation of the Development existing stand, and will be completely interaction of microwave pulses and integrated into the AFEL computer coal began with low power network - The antenna development work in AT- automated control system. The con- analyzer measurements on coal 9 emphasizes broadband, high-peak struction of the 1300-MHz rf system samples. The purpose is to learn the power radiators for transient EMP used for the AFEL will be a collaborative dielectric constant and loss tangent of for wideband-VLE field testing and effort between AT-5, AT-7, and AT-9 coal as a function of frequency and to impulse radar. Our development goals in 1993. study the variations of these parameters are to maximize bandwidth and voltage among different samples. The next breakdown capability while minimizing stop involves setting up the chemical dispersion. The latest antenna devel- diagnostics for the high-power tests. oped is a modified ridged-waveguide transverse-electric mode structure used In collaboration with CLS-4 (Photo for GPR and supplied lo Air Force and Chemistry and Photo Physics), we Army laboratories in 1992. evaluated various chemical analysis techniques from gas chromatography to mass spectroscopy. as well as more advanced techniques employed 106 Accelerator Technology Division Technical Highlights • AT-9 • Verv High-Power Microwave Sources and Effects A ccelerator Technology Division 107 Technical Highlights • AT-10 • GTA instiilUition, Commissioning, and Opcuitiims Introduction 109 Background 109 Achievements 109 Injector Systems 109 GTA Beam Commissioning... /// High-Power Cavity Condition- ing and Preparation /// Safety Systems Modification . 112 Cryogenic Cooling System.... 112 Beainline Alignment 112 Facility Support and Installation 113 DARHT Support 113 Future Plans 113 Accelerator Technology Division Technical Highlights ' AT-10 • GTA Installation, Commissioning, and Operations Introduction NPB program. Although some assembly of a cw H ion source. This negative-ion development will con- year marked our first serious entry into The primary mission of AT-10 has tinue, we anticipate that most of our the design of high-current, proton ion been to support Ground Test Accelera- future work will require high-current, injectors, a venture that may be essential tor (GTA) beam experiments. AT-10 cw positive-ion or proton injectors. As for any of several emerging programs. is responsible for ion-injector develop- a result, our latest thrusts are toward the ment, final beamline installation of integrated development of cw injector Achievements GTA components, and commissioning technology. AT-10 will continue to and operation of the accelerator. We support GTA installation, operation, Injector Systems perform the final radio-frequer.cy (rf) and commissioning. The experience caviry preparation, conditioning, gained and lessons learned in these Operational reliability of the GTA alignment, and integrated checkout. endeavors will be applied to future AT- injector was improved during FY 1992, Our responsibility includes supplying Division projects. and consistent high-current, good- all facility interfaces, water and cryo- emittunce beams were obtained. A cooling. vacuum systems, and power One of our senior staff members has modification of the extractor and emitter wiring. Coordination of all beam been assisting with the design of and electrode designs permitted faster and testing or commissioning is done by experiments on the Dual-axis Radio- easier electrode changes. Source AT-10, although specific experiments graphic Hydrodynamic Test (DARHT) reliability was improved by several may be led by other groups. facility. In this instance, expertise upgrades to the control system hard- developed on low-energy ion injectors ware, the installation of improved Beam commissioning is the final step is proving very useful for a high- Allen-Bradley modules, and the in ;he integrated quality-assurance current electron induction linac. installation of noise-suppression process for verifying the performance electronics. Changes in stait-up of assembled beam hardware. We use Background procedures, operating points, and tuning extensive beam diagnostic equipment have contributed to make recent source with integrated computer systems to Much of the group's work in FY 1992 operation more consistent and have measure beam parameters. Using was devoted to the commissioning and produced brighter beams. these measurements, we compare operation of the GTA hardware and actual performance with that predicted characterization of the GTA beam. Two Lambertson steering coils were by beam-simulation codes. Validation Cooling (at 20 K) for the cryogenic designed, built, and installed inside the jf these codes is essential for improv- GTA was provided by a 750-W helium hores of the two low-energy, beam- ing confidence in future designs. refrigerator. Installation and accep- transport (LEBT) solenoid magnets. tance tests of a 40-kW cryo-cooling These coils give much-needed beam Group AT-10 was formed with its system were completed this year. steering into the radio-frequency current mission in the fall of 1989: Future experiments will use the quadrupole (RFQ). Figure 9.1 shows previously it had been AT-2. whose increased capacity of this boiling- these steering coils during assembly. A sole purpose since 1978 was to hydrogen cooling system. reduction in LEBT length earlier in the develop neutral particle beam (NPB) year was instrumental in reducing technology. Now the group"s mission We made • number of performance emittance growth between the ion is changing again to reflect the broader improver .s to the GTA injector this source and RFQ. responsibilities required by new year and proceeded with initial beam projects. In the past, we concentrated characterization of the intertank On the off-line discharge test stand on developing high-current, high- matching section (IMS) and the first (DTS), we installed a new 4X ion brightness negative-ion sources and GTA drift-tube linac (DTL) module. source that incorporates several design injectors, such as those needed for the Meanwhile, we continued with the upgrades. The most significant upgrade is a new gas-pulser that uses a modified, low-cost, automotive fuel-injection valve to replace the previous piezoelec- tric valve. The new system reduced the total gas flow by nearly a factor of 3, without affecting arc operation. A reduction in hydrogen consumption may be important for reducing emittance growth in the LEBT. Configuration and cooling improvements were also made on this new source. Fig. 9.1. Lumberlsim steering mils during assembly. Accelerator Technology Division 109 Technical Wfihlinhts • AT-10 • OTA Installation, Commisxionina, and Operations We have designed, built, and tested a APT and Accelerator Based Conversion gas densities, thus determining when new controllable arc-current pulser on reviews. the beam became over neutralized. the DTS. This pulser uses HEXFF.Ts Proper space-charge neutralization is to control the source arc current; the We have also used internal funding to essential to eliminate problems with HHXFETs replace the transistor on/off continue collaboration with the Chalk plasma instabilities in H beams. switch and ballast resistors. With this River Laboratory (CRL) and Grumman Figure 9.2 shows the observed compen- arc-current control, we have the Corp. In FY 1993. we will ship $SM of sation factor (0 a.i a function of gas possibility of programming the time operating evv test-stand equipment from density. dependence of the arc current during CRL to Los Alamos. Continued testing the arc macropulse. and development of this cw equipment We developed a low cost, powerful, at Los Alamos in subsequent years commercially based data acquisition I'sing internal Laboratory funding, we should strengthen our design capability and control system on the high-current developed initial designs of a high- for high-current proton accelerators. test stand (HCTS). This stand-alone eurreni. cw proton injector, suitable for system is based on a Macintosh projects such as the accelerator In related work, we analyzed data computer and expandable LABVIEW transmutation of waste (ATW) or the recorded in previous years with a lour- software, a graphical programming accelerator production of tritium gi id electrostatic analyzer to determine environment supported by National (APT). A very similar D' injector details of the space-charge neutraliza- Instruments. The HCTS uses CAMAC might be needed for a Fusion Materials tion of high-current H beams in low- and GP1B for all hardware interfacing, Irradiation Facility IFMIF). To energy transport. This diagnostic but future options include VXI/VME. facilitate our design effort, we com- determines the internal beam potential Allen Bradley, and high-speed, wave- piled available information from cw by measuring the energy cutoff of the form digitization. Provisions have been test stands both past and present. An escaping charged particles. Using the made to expand the present system to extractor and solenoidal-focusing measured energy distribution of the multiple computers as well as multiple LEBT were designed for 75-keV. 140- ejected positive ions, we measured the platforms including SUN and IBM-PC- mA hydrogen-ion beams. The inte- degree of neutralization or compensa- compatible systems. The software is grated design was presented at internal tion as a function of argon and xenon based on the concept of multiple interactive pop-up windows, which give the operator detailed multilevel 1.04 ' A monitoring and control of the hardware. A A A A A We have been running design codes for c 1 01 ion extractors, including a custom a. A O ° design code and SNOW to simulate the E o 1.02 A Q - plasma/beam interlace and details of U 01 the ion trajectories. These codes were A A ec used to optimize the CRL cw test-stand injector performance. Subsequent tests U \ confirmed a modest improvement in Positive ion data, Ao 1.00 1 i both beam emittance and divergence. Q. In the future we will be forced to en 1 extend available design codes when Electron data, E p designing the high-current, low- CO A \ divergence cw beams needed on ' i expected new programs. v 0.98 A | Ar and Xe Neutralizing Gases 01 The pulsed KX source tests verified the u | i " Ar gas scaling laws used to design the 8X * Xe gas source las applied to the 4X source) I(n and showed that there are no physics " g°i \ obstacles lo building a cw 8X source. 0.96 —• 1 i i . i 0.0 0.2 0.4 0.6 0.8 1.0 Our collaborator. Grumman Space Systems completed construction of the 3 1 cw 8X ion source this year. We I (n a . ) do" cm" ) assembled and installed this source, along with a new high-pressure, healed. I-iv. '1.2. < '(Kii/ii-iiMi/idii tailor IJ) o\ a fimdion of\' IK) Accelerator Technology Division Technical Highlights • AT-IO • CTA Installation, Commissioning, and Operations cooling water system on the modified position monitoring at several loca- High-Power Cavity Conditioning and HCTS. Testing of this cw H~ ion source tions. Beam energy and phase were Preparation should commence early in FY 1993. measured versus IMS buncher field, giving excellent agreement with design We have successfully conditioned three Using the pulsed 8X source, we found predictions. Figure 9.3 shows the DTL modules. A successful condition- that placing a conical collar at the observed buncher gap voltage versus ing consists of operating the modules at emission aperture reduced the e7H~ ratio cavity power and shows that the design 20% over the required power levels for to 0.9/1 with no decrease in the H~beam gap voltage occurs at predicted power 2-ms rf pulse durations. The modules current. Without a collar, the typical e~/ level. The beam steering and emittance must also operate for long periods of H~ ratio is between 4/1 and 5/1. A measurements are being used to time (tens of minutes) with little or no barium cathode was tried in the 4X produce a steering and matching model breakdown. As in the case of the RFQ, source in place of the cesium-coated, of the IMS. These models are being the DTL module 1 reconditions in less molybdenum cathode after we learned used again in DTL experiments to than 0.5 hour after extended exposure that a barium insert near the emitter of a verify the predicted performance of the to the atmosphere and immediately cusped-field volume source increases DTL. each morning after an 8-hour the H~ current from that source by about nonoperation period. a factor of 3. All indications are that the We conducted the first beam operation 4X source H~ output will be very low of DTL module 1 in September 1992 and the e~/H~ ratio will be very high if a and produced a 3.2-MeV output. barium cathode is substituted for a Future runs are planned for November cesium-coated, molybdenum cathode; 1992. We measured the transverse therefore, we plan to use only cesium- emittance of the DTL beam for a coated, molybdenum cathodes in the 8X variety of input beam conditions and source. DTL operating set points. GTA Beam Commissioning A series of GTA beam runs were completed during FY 1992. In the spring, we fully characterized the output beam and operation of the IMS. This 0.27 structure includes two rf bunching cavities and six permanent-magnet quadrupoles, two of which can be 0.26 - translated for beam steering and four of which have adjustable field strengths. The purpose of the IMS is to longitudi- nally and transversely match the RFQ 0.25 - output beam to the following DTL. u0) By maximizing RFQ transmission, we a> 0.24 determined the optimal RFQ input match. The resulting Courant-Snyder parameters agreed with predictions. 0.23 a> @ Design Cavity Power During IMS testing, we measured both Expected energy 0,232 MeV the transverse and longitudinal beam LU emittances for a variety of IMS quadru- 0.22 pole and buncher field strengths. We also measured the effects of beam steering in the IMS. The LINDA 0.21 diagnostic remains the predominant 3.0 4.0 5.0 6.0 method for characterizing the longitudi- Cavity Power (kW) nal-beam properties. In spite of identi- fied difficulties, microstrip probes were used extensively for beam-centroid Fig. 9.3. Energy difference between acceleration and deacceleralion modes for cavity A. Accelerator Technology Division 111 Ttvlmia AT-Hi • VTA Installation, Commissioning:, and Operations Safety Systems Modi/nation nary cooling through a LN, to gaseous ments in this vessel confirmed that the helium (GHe) heat exchanger and its required alignment was maintained The Radiation Protection Safety primary refrigeration capability from a under vacuum and cryogenic conditions System was modified to include the helium-lo-liquid-hydrogen heal for the first four DTL modules. We first DTL module. This hardware- exchanger. The coolant pressure is 324 have adapted the MMTW system to based system is modeled on the one psig and the coolant flow rate is 484 g/s measure not only the DT magnet used at Clinton P, Anderson Meson at 60% of the turbo-compressor speed. centers, but also the magnet roll angle. Physics Facility (LAMPF) and is We found that all DT magnet roll designed to exclude personnel from the We completed the final construction of angles met the ± 0.5 degrees specifica- beam area whenever a radiation hazard the CCS and numerous reports and tion except one that had a one-degree might exist from beam operations. All studies for the operational readiness roll angle. GTA beam operations (with the requirements. On May I, we received exception of the 750-W cryo refrigera- approval to take delivery of 15,000 We completed a number of floor tor) are conducted from the fully gallons of liquid hydrogen to support layouts in preparation of moving the functional control room. the system acceptance tests which were existing accelerator and setting the ten successfully completed on May 8. DTL modules. We also performed Cryogenic Cooling System Figure 9.4 shows the compressor and alignment for the Advanced Free mechanical components of the CCS. Electron Laser. We presently cool the GTA beamline components to cryogenic temperatures Beamline Alignment While on an off-site assignment to with i Koch 750-W refrigerator. We AecSys Technology, one of our operate a second refrigerator during During FY 1992, we internally aligned engineers provided linac design support multiple-magnet taut-wire (MMTW) the drift lubes (DT) in four DTL for the Superconducting Super Collider measurements made on the IMS and modules to an accuracy of 0.001 in. at Laboratory. He provided the analysis DTL modules at cryogenic tempera- room temperature. The goal is to of the DTL temperature control system tures. The new 40-kW cryogenic maintain 0.002 in. alignment when and the specification of the cooling and cooling system (CCS) will be required operational at 20 K and under vacuum. heating systems. He also designed and for all GTA experiments that involve A second MMTW alignment system specified the rf power waveguide and more than the RFQ, IMS. and first DTL was built and installed in an off-line window assembly. module. This CCS obtains its prelimi- cryo-vacuum test vessel. Measure- Fig. 9.4. Compressor and mechanical components of the CCS. 112 Accelerator Technology Division Technical Highlights • AT-10 ' GTA Installation, Commissioning, and Operations Facility Support and Installation AT-10's major responsibility has been Future Plans to debug and use beam dynamics codes AT-10 installed all GTA vacuum for the end-to-end electron-beam For much of FY 1993, we will be vessels and fulfilled all operational simulation. With this code, linear beam preparing test-stand hardware for vacuum and cooling requirements. We dynamics and nonlinear beam-breakup testing components and systems needed + continue to operate the helium refrig- centroid motion can be tracked as a for high-current H and H~ cw ion erators for GTA beamline experiments, function of time during the beam injectors. The initial test-stand high-power conditioning, and align- macropulse. Some results indicate that configuration will permit us to test and ment verifications at cryogenic space-charge effects are critical to the compare several candidate ion sources. temperatures. All upgrades, additions, beam-breakup motion and can be Later expansions of these stands will and maintenance to the GTA facility mitigated only by careful design of the allow us to add and test transport building as well as GTA electrical beam-transport system. AT-10 has also components and, finally, to match installations are our responsibility. contributed to the data acquisition and beams into a RFQ. Electrical installations include the if analysis systems on the magnetic mezzanine utility rack and distribution spectrometer, which will measure the Possible future projects such as the systems: CCS Instrumentation and time-dependent beam energy waveform APT, the ATW, the FMIF, and possible Control, fire alarm, and protection to less than 0.5%. major expansion of LAMPF and systems; the telephone and paging Manuel Lujan, Jr. Neutron Scattering system upgrades; experiment 2 A Center will all require about 100 mA of beamline power-distribution system; protons or H~ ion currents. Individual control room and computer rooms components have been developed that electrical additions; power distribution might meet these basic needs, but our to the mock-up DTL vacuum tank area; primary focus will be to integrate the environmental, safety, and health technologies needed for building a upgrades and electrical power distribu- practical ion injector. tion system remodels; ground planes installations in the rf powei area; and We will continue to install GTA experiment 2D and 3 injector power components and will move the GTA to trunk wiring installation. a new location within the beam tunnel in preparation for experiments 2D and DARHT Support 3. In support of this move, we will supply all the utilities and will com- One of our senior staff members has plete the floor installation. We will been actively supporting the DARHT again lead the commissioning efforts induction-linac electron accelerator on the first GTA DTL module and on project for the past 3 years. The first the modified IMS and will work with stage of the DARHT accelerator was the other GTA groups in analyzing the completed this past year, and measure- data. We plan to complete the align- ments of the 6-MeV, 3-kA beam are ment and the high-power conditioning under way. Modifications of the of the remaining DTL modules. injector pulsed-power system reduced voltage fluctuations during the pulse flattop to less that 19c rms. Insulator failures on the 4-MeV DARHT injector appeared to result from insulator surface charging. A device was built that measures and corrects if necessary the pulse-to-pulse charge buildup. In initial tests, this device discharged the insulator rings after each pulse; the tests for solving the insulator-breakdown problem were very encouraging. Accelerator Technology Division 113 Appendix A * Publications AT-DO R. A. Jameson, G. P. Lawrence, and S. O. Schriber, "Accelerator-Driven Transmu- tation Technology tor Energy Production and Nuclear Waste Treatment," European Particle Acceleratory Conference, Berlin, Germany, March 1992, Los Alamos National Laboratory document LA-UR-92-865. R. A. Jameson, "On Scaling and Optimization of High-Intensity," to be published in the Proceedings of the Third Workshop on Advanced Accelerator Concepts, Long Island, NY, June 14-20,1992, Los Alamos National Laboratory document LA-UR- 92-2474. R. L. Sheffield, "Extreme Ultraviolet Free Electron Lasers," 1992 IEEE Lasers and Electro-Optical Society Annual Meeting, Boston, MA, November 1992, Los Alamos National Laboratory document LA-UR-92-2629. R. L. Sheffield, B. E. Carlsten, and L. M. Young, "High-Brightness Linac for the Advanced Free-Electron Laser Initiative at Los Alamos," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2804. R. A. Hardekopf, "Workshop on Plasma Focus Device Utility for Intense Neutron Source Applications," Los Alamos, NM, July 21-22, 1992, Los Alamos National Laboratory document LA-UR-92-3552. E. A. Heighway, "The Path to the Neutral Particle Beam (NPB) Weapon," 1992 NPB Symposium, Argonne, IL, April 1992, Los Alamos National Laboratory document LA-CP-92-241. AT-1 G. J. Vogt, F. D. Gac, J. D. Katz, B. Rusnak, and W. P. Unruh, "Microwave-Driven Spray Drying Annual Report, FY 1991," Los Alamos National Laboratory docu- ment LA-UR-92-660. G. Spalek, "Developmental Cavity Dimensions," Los Alamos National Laboratory document LA-UR-92-1246. G. Spalek, "Voltages and Multipacting Regions in Coaxial Line Choke Joints," Los Alamos National Laboratory document LA-UR-92-1344. G. Spalek, "805 MHz Single Cell Test Cavity End Flange Power Dissipation and HPP Coupler External Q's," Los Alamos National Laboratory document LA-UR- 92-1345.' G. Spalek, "Maximum Electric Field in 50 OHM Coaxial Lines for rf Couplers," Los Alamos National Laboratory document LA-UR-92-1346. G. Spalek, "Single Cell 805 MHz Test Cavity Field Calibration Constants Shape Same as End 1/2 Cells of 7 Cell Developmental Cavity," Los Alamos National Laboratory document LA-UR-92-1347. G. Spalek, "Variable Coupler Chock Joint Bandwidth," Los Alamos National Laboratory document LA-UR-92-1348. 116 Accelerator Technology Division Appendix A • Publications G. Spalek, "Developmental 7-Cell Cavity 2" Coax rf Power Coupler Travel," Los Alamos National Laboratory document LA-UR-92-1349. G. Spalek, "'Single Cell 805 MHz Test Cavity Field Calibration Constants," Los Alamos National Laboratory document LA-UR-92-1350. G. Spalek, "Summary of Tuning Stresses and Loads for the 7-Cell Developmental Superconducting Cavity," Los Alamos National Laboratory document LA-UR-92- 1351. G. Spalek, "Bandwidth of Quarter Wavelength Stub Supported Coaxial Line," Los Alamos National Laboratory document LA-UR-92-1814. E. R. Gray, "Helium Displacement," Los Alamos National Laboratory document LA-UR-92-2330. R. W. Garnett, D. J. Liska, G. P. Lawrence, and T. H. Larkin, "Design and Simula- tion of a Bridge-Coupled DTL Structure for the 20-80 MeV Region of a Proton Linac for Accelerator Transmutation of Waste (ATW)," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28,1992, Los Alamos National Laboratory document LA-UR-92-2663. B. Rusnak, J. N. DiMarco, W. Diete, R. G. Maggs, A. H. Shapiro, and P. V. Wright, "Evaluation of Surface Contamination and Cleaning Techniques on Superconduct- ing rf Cavities," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2754. L. M. Young and S. Nath, "Effect of Transients on the Beam in the SSC Coupled Cavity Linac," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2768. D. Schrage, L. Young, J. Billen, W. Clark, R. DePaula, G. Neuschaefer, P. Roybal, J. Stovall, and A. Naranjo, "Radio Frequency Quadrupole Lihnac for the Supercon- ducting Super Collider," Application of Accelerators in Research and Industry Conference, Denton, TX, November 2-5, 1992, Los Alamos National Laboratory document LA-UR-92-2962. D. Schrage, L. Young, R. Aiken, W. Clark, R. DePaula, C. Gladwell, F. Martinez, A. Naranjo, P. Roybal, and J. Stovall, "University of Twente Photocathode Linac," Application of Accelerators in Research and Industry Conference, Denton, TX, November 2-5, 1992. Los Alamos National Laboratory document LA-UR-92-2963. T. P. Wangler, A. G. Cimabue, J. L. Merson, R. S. Mills, R. L. Wood, and L. M. Young, "Superconducting RFQ Development at Los Alamos," 1992 Linac Confer- ence, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Labora- tory document LA-UR-92-2968. J. E. Stovall, "A Review of RF Photocathode e- Sources," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-3034. T. P. Wangler, A. G. Cimabue, J. L. Merson, R. S. Mills, R. L. Wood, and L. M. Young, "Superconducting RFQ Development at Los Alamos," 12th Intl. Conf. on the Application of Accelerators in Research and Industry, Dei!ton, TX, November 2-5, 1992, Los Alamos National Laboratory document LA-UR-92-3076. Accelerator Technology Division 117 Appendix A * Publications R. L. Wood, L. M. Young, D. J. Aikin, W. L. Clark, R. F. DePaula, C. Gladwell, J. E. Ledford, F. A. Martinez, and J. E. Stovall, "Photocathode Electron Linac for AFEL," Application of Accelerators in Research and Industry Conference, Denton, TX, November 2-5,1992, Los Alamos National Laboratory document LA-UR-92- 3215. AT-3 J. D. Gilpatrick, "RFQ and IMS Commissioning Beam Diagnostics Measure- ments," Los Alamos National Laboratory document LA-UR-91-3965. B. Blind, "A Choice of Point-to-Parallel Focusing Modules," Los Alamos National Laboratory document LA-UR-92-422. R. H. Kraus, Jr., "Permanent-Magnet Material Applications in Particle Accelera- tors," Twelfth Int. Workshop on Rare Earth Magnets and their Applications, Canberra, Australia, July 12-15,1992, Los Alamos National Laboratory document LA-UR-92-1677. R. E. Shafer and J. Johnson, "Electrical Characteristics of the SSC MEB Magnet String," Los Alamos National Laboratory document LA-UR-92-1766. R. E. Shafer and K. Smedley, "Measurement of AC Electrical Characteristics of SSC Superconducting Dipole Magnets," XVth International Conference on High Energy Accelerators, Hamburg, Germany, July 20-24,1992, Los Alamos National Laboratory document LA-UR-92-2179. R. E. Shafer and Kay Smedley, "Electrical Characteristics of Long Strings of SSC Superconducting Dipoles," XVth International Conference on High Energy Accelerators, Hamburg, Germany, July 20-24, 1992, Los Alamos National Labora- tory document LA-UR-92-2180. R. E. Shafer, "Beam Loss Monitoring at SSC and LHC," Los Alamos National Laboratory document LA-UR-92-2302. C. R. Rose, C. M. Fortgang, and J. P. Power, "GTA Beamloss-Monitor System," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2630. F. D. Wells, R. E. Shafer, and J. D. Gilpatrick, "Log-Ratio Beam Position Monitor- ing at 425 MHz," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2666. J. F. Power, J. D. Gilpatrick, F. Neri, and R. B. Shurter, "Characterization of Beam Position Monitors in Two-Dimensions," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR- 92-2726. D. P. Sandoval. R. C. Garcia, J. D. Gilpatrick, M. A. Shinas, R. Wright, V. Yuan, M. E. Zander, and K. F. Johnson, "Video Profile Monitor Diagnostic System for GTA," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2727. J. D. Gilpatrick, H. P. Marquez, J. F. Power, and V. Yuan, "Design and Operation of a Bunched-Beam, Phase-Spread Measurement," 1992 Linac Conference, 118 Accelerator Technology Division Appendix A • Publications Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2728. R. H. Kraus, Jr., D. B. Barlow, and R. Meyer, "A Variable-Field Permanent-Magnet Dipole for Accelerators," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-HR-92-2850. P. L. Walstrom, "Magnetic Fields from Distributions of Dipoles on Cylindrical Surfaces," Los Alamos National Laboratory ducument LA-UR-92-3496. A. Jason, R. Hardekopf, G. Lawrence, R. Macek, R. Pynn, and G. Russell, "LANSCE The Los Alamos "1 MW" Spallation Source," Los Alamos National Laboratory document LA-UR-92-3497. D. B. Barlow, R. H. Kraus, Jr., P. F. Ruminer, and C. T. Lobb, "Cryogenic and Room Temperature Mapping of GTA Drift-Tube Linac Permanent Magnet Quadru- poles," 1992 NPB Symposium, Argonne, IL, April 1992, Los Alamos National Laboratory document LA-CP-92-210. P. L. Walstrom, "Three-Dimensional Field Models for High-Order Beam-Optics Codes," 1992 NPB Symposium, Argonne, IL, April 1992, Los Alamos National Laboratory document LA-CP-92-222. W. P. Lysenko and P. J. Channell, "Testing the New BEDLAM Optics Code," 1992 NPB Symposium, Argonne, IL, April 1992, Los Alamos National Laboratory document LA-CP-92-223. C. T. Mottershead, "NPB Telescope Design," 1992 NPB Symposium, Argonne, IL, April 1992, Los Alamos National Laboratory document LA-CP-92-252. AT-4 E. O. Ballard, K. E. Christensen, and P. P. Prince, "Ground Test Accelerator (GTA) Drift Tube Linac (DTL) Fabrication and Assembly Status," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2643. W. E. Fox, and N. K. Bultman, "Transition Fittings Between Aluminum and Stainless Steel Components of Cryogenic Accelerators," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2644. D. J. Liska, J. Ledford, S. Black, G. Spalek, and J. N. DiMarco, "Design Features of a Seven-Cell High-Gradient Superconducting Cavity," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2734. S. Black and G. Spalek, "Calculation of Mechanical Vibration Frequencies of Stiffened Superconducting Cavities," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR- 92-2735. D. J. Liska, P. Smith, L. Carlisle, T. Larkin, G. Lawrence, and R. Garnett, "Me- chanical Features of a 700-MHz Bridge-Coupled Drift Tube Linac," 1992 Linac Accelerator Technology Division 119 Appendix A • Publications Conference, Ottawa, Ontario, Canada, August 23-28, i992, Los Alamos National Laboratory document LA-UR-92-2736. E. O. Ballard, K. E. Christensen, and P. P. Prince, "Ground Test Accelerator (GTA) Drift Tube Linac (DTL) Fabrication and Assembly Status," 1992 NPB Symposium, Argonne, IL, April 1992, Los Alamos National Laboratory document LA-CP-92- 234. AT-5 A. Regan, "Upconverter Module User's Manual," Los Alamos National Laboratory manual LA-12395-M (April 1992). C. Ziomek, "Vector Modulator Module Manual," Los Alamos National Laboratory manual LA-12396-M (April 1992). T. Brooks, "Timing Receiver Module User's Manual," Los Alamos National Laboratory manual LA-12401-M (May 1992). C. Ziomek, "I Controller Module User's Manual," Los Alamos National Laboratory manual LA-12403-M (April 1992). C. Ziomek, "Q Controller Manual," Los Alamos National Laboratory manual LA- 12404-M (April 1992). S. Jachim, "Vector Detector Module User's Manual," Los Alamos National Laboratory manual LA-12406-M (May 1992). C. Ziomek, "Timing Distribution Module User's Manual," Los Alamos National Laboratory manual LA-12408-M (May 1992). C. Ziomek, "Low-Level RF Lab VIEW Control Software User's Manual," Los Alamos National Laboratory manual LA-12409-M (June 1992). A. Regan, "Downconverter Module User's Manual," Los Alamos National Labora- tory manual LA-12438-M (June 1992). M. Curtin. "Envelope Detector Module User's Manual," Los Alamos National Laboratory manual LA-12444-M (May 1992). M. Curtin, "425-MHz Envelope Detector Module User's Manual." Los Alamos National Laboratory manual LA-12445-M (May 1992). C. Ziomek. "Adaptive Feedforward Module User's Manual," Los Alamos National Laboratory manual LA-12463-M (June 1992). P. Denney, "Monitor Transmitter Module," Los Alamos National Laboratory manual LA-12473-M (June 1992). D. Rees. "Test Procedures, SSC 4616 Tetrode Amplifier," Los Alamos National Laboratory document LA-UR-91-3856. D. Rees. "Conduct of Operations 425-MHz Tetrode Amplifier," Los Alamos National Laboratory document LA-UR-9I-39I8. 120 Accelerator Technology Division Appendix A • Publications D. Rees, "University of Twente Klystron Driver High-Power Radio-Frequency System-System Description," Los Alamos National Laboratory document LA-UR- 92-351. D. Rees, "University of Twente Klystron Driver High-Power Radio-Frequency System Test Procedures and Results," Los Alamos National Laboratory document LA-UR-92-352. W. Reass and W. North, "Electrical Design and Operation of a Two-Klystron rf Station for the Los Alamos National Laboratory's Neutral Particle Beam Experi- ment," 1992 Power Modulator Symposium, Myrtle Beach, SC, June 23-25, 1992, Los Alamos National Laboratory document LA-UR-92-1888. A. H. Regan, D. Brittain, D. E. Rees, and C. D. Ziomek, "RF System Description for the Ground Test Accelerator Radio-Frequency Quadrupole," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2706. C. D. Ziomek, "Adaptive Feedforward in the LANL rf Control System," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2807. D. Rees and C. Friedrichs, "RF System Work in Support of LAMPF Upgrade," Los Alamos National Laboratory document LA-UR-92-2898. AT-7 P. J. Channell, "The Vlasov Equation and POISSON Maps Induced by Non- Symplectic Particle Maps," to be published in Physics Letter A, Los Alamos National Laboratory document LA-UR-91-3261. D. H. Fitzgerald, T. W. Hardek, R. L. Hutson, R. J. Macek, H. A. Thiessen, T. F. Wang, D. V. Neuffer, and E. P. Colton, "Observations of a Fast Transverse Intability in the PSR," to be published in Nuclear Instruments and Methods in Physics Research, Section A, Los Alamos National Laboratory document LA-UR- 91-3929. T. Baits and j. Merson, "Users' Notes for POISSON/SUPERFISH Release 3.0," Los Alamos National Laboratory document LA-UR-91-4140. B. E. Carlsten, M. V. Fazio, R. J. Faehl, T. J. T. Kwan, D. G. Rickel, and R. M. Stringfield, "Theory and Modeling of a Relativistic Klystron Amplifier with High Space Charge for Microsecond Applications," to be published in SPIE Intense Microwave & Particle Beams III, Lcs Alamos National Laboratory document LA- UR-91-4150. M. J. Browman, "Program Power," Los Alamos National Laboratory document LA- UR-92-475. M. J. Browman, "Special MAFIA Postprocessors and Software Tools," Los Alamos National Laboratory document LA-UR-92-476. B. E. Carlsten, M. V. Fazio, R. J. Faehl, T. J. Kwan, D. G. Rickel, R. D. Ryne, and R. M. Stringfield, "Effect of Intense Space Charge in Relativistic Klystron Amplifi- ers," Beams 92 Conference, Washington, D. C, May 25-29, 1992, Los Alamos Accelerator Technology Division 121 Appendix A • Publications National Laboratory document LA-UR-92-1594. T-S. F. Wang, "Beam-Loading Stability in Synchrotrons with „ Higher rf Har- monic," XVth Int. Conference on High Energy Accelerators, Hamburg, Germany, July 20-24, 1992, Los Alamos National Laboratory document LA-UR-92-2086. R. K. Cooper and R. D. Ryne, "Recent Activities in Accelerator Code Develop- ment," Advanced Accelerator Concepts Workshop, Port Jefferson, NY, Los Alamos National Laboratory document L A-UR-92-2174. M, J. Browman and A. Lombardi, "Testing Program Fields," Los Alamos National Laboratory document LA-UR-92-2372. M. J. Browman, "Notes on Program Fields." Los Alamos National Laboratory document LA-UR- »2-2373. K. C. D. Chan, K. Meier, D. Nguyen, R. Sheffield, T. S. Wang. R. W. Warren, W. Wilson, and L. M. Young. "Design of a Compact Application-Oriented Free- Electron Laser." 1992 Linac Conference. Ottawa. Ontario, Canada, August 23-2R, 1992, Los Alamos National Laboratory document LA-UR-92-2515. B. E. Carlsten, J. C. Goldstein, E. J. Pitcher, and M. J. Schmitt, "Simulations of APEX Accelerator Performance in the New Nonthermalized Photoinjector Re- gime," 14th Int. Free Electron Laser Conference, Kobe, Japan, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2561. B. E. Carlsten, J. C. Goldstein, P. G. O'Shea, and E. J. Pitcher, "Measuring Emit- tance of Nonthermalized Electron Beams from Photoinjectors," 14th Int. Free Electron Laser Conference, Kobe, Japan, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2562. D. W. Feldman, S. C. Bender, D. A. Byrd, B. E. Carlsten. R. B. Feldman, J. C. Goldstein. R. Martineau, P. G. O'Shea, E. Pitcher, M. J. Schmitt, W. E. Stein, and M. Wilke, "Operation of the APEX Photoinjector Accelerator at 40 MeV," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2645. M. J. Browman. "Special MAFIA Postprocessors for the Analysis of rf Structures," 1992 Linac Conference, Ottawa. Ontario. Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2677. C. M. Fortgang, "Field Correction in Three-Dimensions for a One-Meter Long Permanent Magnet Wiggler," 1992 Linac Conference, Ottawa. Ontario, Canada. August 23-28. 1992. Los Alamos National Laboratory document LA-UR-92-2678. M. D. Wilke. P. G. O'Shea. E. J. Pitcher. R. B. Feldman, and A. Lumpkin, "Elec- tron-Beam Diagnostics Development for the Los Alamos FEL Facility," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2692. P. G. O'Shea, B. E. Carlsten, D. W. Feldman, R. B. Feldman, and K. F. McKenna, "Performance of the APEX 40 MeV Photoinjector-Driven Linear Accelerator," Advanced Accelerator Concepts Workshop, Brookhaven National Laboratory, June 14-18. IQ92, Los Alamos National Laboratory document LA-UR-92-2725. 122 Accelerator Technology Division Appendix A • Publications D. Nguyen, D. M. Baca, K. C. D. Chan, R. B. Cheairs, et al., "Initial Performance of Los Alamos Advanced Free Electron Laser." 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2803. R. L. Sheffield, B. E. Carlsten, and L. M. Young, "High-Brightness Linac for the Advanced Free-Electron Laser Initiative at Los Alamos," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2304. R. W. Warren and C. M. Fortgang, "Development of a Pulsed Microwiggler System," 1992 FEL Conference, Kobe, Japan, August 24-28, 1992, Los Alamos National Laboratory document LA-UR-92-2805. P. G. O'Shea and M. Reiser, "Report on the High-Brightness Source Working Group," Advanced Accelerator Concepts Workshop, Brookhaven National Labora- tory, June 14-18, 1992, Los Alamos National Laboratory document LA-UR-92- 2809. R. W. Warren, P. G. O'Shea, S. C. Bender, B. E. Carlsten, J. W. Early, D. W. Feldman, et. al, "Lasing Attempts with a Microwiggler on the Los Alamos FEL," 1992 FEL Conference, Kobe, Japan, August 23-28, 1992, Los Alamos National Laboratory documem LA-UR-92-3017. P. J. Channell and Harry Dreicer, "An Intense Source of Positrons Using a Low Energy Proton Beam," Advanced Accelerator Concepts Workshop, Brookhaven National Laboratory, June 14-18, 1992, Los Alamos National Laboratory document LA-UR-92-3165. H. Takeda, "Modeling the APLE Injector Solenoid Magnetic Field with the Biot- Savart Law." 14th Int. Free Electron Laser Conference, Kobe, Japan, August 25-29, 1992. Los Alamos National Laboratory document LA-UR-92-3231. G. W. Rodenz, "Users Guide for the Program FRONT," Los Alamos National Laboratory document LA-UR-92-3396. R. K. Cooper, "Release Notes for POISSON/SUPERFISH 4.0," Los Alamos National Laboratory document LA-UR-92-3397. AT-8 A. Kozubal, "Automation from Pictures: Producing Real-Time Code from a State Transition Diagram," ICALEPCS '91 Conference, Tsukuba. Japan, November 11- 15. 1991. Los Alamos National Laboratory document LA-UR-91-3340. L. R. Dalesio, M. R. Kraimer, and A. J. Kozubal. "EPICS Architecture." 1CALEPCS "91 Conference. Tsukuba. Japan, November 11-15, 1991, Los Alamos National Laboratory document LA-UR-91-3543. W. C. Mead, P. S. Bowling, S. K. Brown, R. D. Jones, C. W. Barnes. H. E. Gibson, J. R. Goulding, and Y. C. Lee, "Optimization and Control of a Small-Angle Negative Ion Source Using an On-Line Adaptive Controller Based On the Connectionist normalized Local Spline Neural Network," Los Alamos National Laboratory document LA-UR-91-3670. Accelerator Technology Division 123 Appendix A • Publications S. K. Brown, P. S. Bowling, H. E. Gibson, R. G. Jacobson, W. B. Ingalls, and D. R. Schmitt, "Progress on the Automation of DTS," Los Alamos National Laboratory document LA-UR-92-0059. M. E. Zander, R. M. Wright, S. K. Brown, D. P. Sandoval, J. D. Gilpatrick, and H. E. Gibson, "Image Processing and Computer Controls for Video Profile Diagnostic System in the Ground Test Accelerator (GTA)," 1992 Linac Conference, Ottawa, Ontario. Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2354. R. A. Cole and W. H. Atkins, "Real-Time Data Archiving for GTA," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2420. M W. Stettler, M. E. Thuot, L. R. Dalesio, R. A. Cole, C. B. Fite, G. E. Slentz, and D. S. Warren, "A Distributed Timing System for Synchronizing Control and Data Correlation," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2422. W. H. Atkins and R. G. Jones, "The Run Permit Protection System for GTA," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2737. M. E. Zander, R. M. Wright. S. K. Brown, D. P. Sandoval, J. D. Gilpatrick, and H. E. Gibson, "Image Processing and Computer Controls for Video Profile Diagnostic System in the Ground Test Accelerator (GTA)," 1992 Neutral Particle Beam Technical Symposium, Argonne, IL, April 27-30, 1992, Los Alamos National Laboratory document LA-CP-92-266. S. K. Brown. W. C. Mead. P. S. Bowling, and R. D. Jones, "Real-Time Optimiza- tion and Control of a Small Angle Ion Source Using an Adaptive Neural Network Controller," Neutral Particle Beam Technical Symposium, Argonne, IL, April 27- 30. 1992, Los Alamos National Laboratory document LA-CP-92-304. AT-9 M. V. Fazio. "Long Pulse Relativistic Klystron High Power Microwave Source Research—1991 Progress Report." Los Alamos National Laboratory document LA- UR-92-744. R. F. Hoeberling. "Electromagnetic Numerical Code Assessment-Final Report," Los Alamos National Laboratory document LA-UR-92-1179. J. Kinross-Wright, "High Power Microwave Testing and Source Report," Los Alamos National Laboratory document LA-UR-92-1180. F. VanHaaften, A. Erickson. and K. Rust. "A Chronology of the BANSHEE Thyratron Switch Medulator Development," Los Alamos National Laboratory document LA-UR-92-1447. M. V. Fazio. B. E. Carlsten, R. J. Faehl, W. B. Haynes, R. F. Hoeberling, T. J. T. Kwan, D. G. Rickel, F. W. VanHaaften, R. M. Stringfield, et al., "The Experimental and Theoretical Development of a One Gigawatt, Repetitively Pulsed, One Micro- second Pulse Length, High Current Relativistic Klystron and Modulator," Beams 92-Ninth International Conf. on High Power Particle BEAMS, Washington, DC, 124 Accelerator Technology Division Appendix A • Publications May 25-29, 1992, Los Alamos National Laboratory document LA-UR-92-1612. R. M. Stringfield, R. M. Wheat, D. J. Brown, M. V. Fazio, J. Kinross-Wright, B. E. Carlsten et al., "Large Orbit Gyroklystron Development at Los Alamos," Beams 92- Ninth International Conf. on High Power Particle BEAMS, Washington, DC, May 25-29, 1992, Los Alamos National Laboratory document LA-UR-92-1656. R. M. Stringfield, R. J. Faehl, M. V. Fazio, R. F. Hoeberling et al., "The Develop- ment of a One Microsecond Pulse Length, Repetitively Pulsed, High Power Modulator and a Long-Pulse Electron Beam Diode for the Production of Intense Microwaves," Beams 92-Ninth International Conf. on High Power Particle BEAMS, Washington, DC, May 25-29, 1992, Los Alamos National Laboratory document LA-UR-92-1695. F. Van Haaften, "BANSHEE-High Voltage Repetitively Pulsed Electron Beam Driver," 1992 Power Modulator Symposium, Myrtle Beach, SC, June 23-25, 1992, Los Alamos National Laboratory document LA-UR-92-1716. S-J. Han, "Stability of an Imploding Spherical Shell," to be published in Physical Review A, Los Alamos National Laboratory document LA-UR-92-1965. M. V. Fazio, B. L. Freeman, R. F. Hoeberling, J. Kinross-Wright, D. G. Rickel, and R. M. Stringfield, "A Microsecond Pulse-Length, Frequency-Stabilized Virtual Cathode Oscillator Using a Resonant Cavity," to be published in IEEE Transactions on Plasma Science, Special Issue on High Power Microwave Generation, Los Alamos National Laboratory document LA-UR-92-2823. AT-10 V. W. Yuan, C. D. Bowman, J. D. Bowman, J. E. Bush, P. P. J. Delheif, C. M. Frankle, C. R. Gould, et al., "Parity Nonconservation in Polarized-Neutron Trans- mission through l39La," Physical Review C, 44, Number 5, 2187-2194, (1991). C. M. Frankle, J. D. Bowman. J. E. Bush, V. W. Yuan, et al., "Parity Nonconservation for Neutron Resonances in 2:1:!Th," Physical Review C, 46, Number 2, 778-787. (August 1992). X. Zhu. J. D. Bowman, C. D. Bowman, J. E. Bush, V. W. Yuan, et al., "Parity Nonconservation for Neutron Resonances in B8U," Physical Review C, 46, Number 2, 768-777, (August 1992). C. M. Frankle, J. D. Bowman, J. E. Bush, V. W. Yuan, et al., "Parity Nonconservation for the 0.88-eV Neutron Resonance in 8lBr," Physical Review C, 46. Number 4, 1542-1545, (October 1992). D. G. Haase, J. D. Bowman, P. P. J. Delheij, V. W. Yuan, et al., "Depolarization of Neutrons in Ferromagnetic Holmium by Means of Enhanced Nuclear Parity Violation in IWLA," Physical Review fi, 46, Number 18,11 290-11 294 (November 1992). H. V. Smith, Jr., J. D. Sherman, C. Geisik, and P. Allison, "H Temperature Dependencies in a Penning Surface-Plasma Source," 4th Int. Conference on Ion Sources, Bensheim, Germany, September 30-October 4, 1991, Los Alamos National Laboratory document LA-UR-91-2802. Accelerator Technology Division 125 Appendix A • Publications H. V. Smith, Jr., P. Allison, C. Geisik, S. D. Orbesen, et al., "Status of 8X H" Ion Source Development," Los Alamos National Laboratory document LA-UR-92- 1950. H. V. Smith and Paul Allison, "Suppression of the e- Coextracted from a Penning Surface-Plasma H~Source," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2553. K. F. Johnson, O. R. Sander, W. H. Atkins, G. O. Bolme, et al., "Commissioning of the Ground Test Accelerator RFQ," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR- 92-2703. K. Johnson, O. Sander, W. Atkins, G. Bolme, S. Brown, R. Connoly, R. Garnett, J. Gilpatrick, F. Guy, W. Ingalls, C. Little, R. Lohsen, S. Lloyd, G. Neuschaefer, J. Power, K. Saadatmand, D. Sandoval, R. Stevens, G. Vaughn, E. Wadlinger, R. Weiss, and V. Yuan, "Commissioning of the Ground Test Accelerator Intertank Matching Section," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23- 28, 1992, Los Alamos National Laboratory document LA-UR-92-2704. R. Connolly, K. F. Johnson, and V. Yuan, "A Correction for Emittance-Measure- ment Errors Caused by Finite Slit and Collector Widths," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2715. O. R. Sander, W. H. Atkins, G. O. Bolme, S. Bowling, S. Brown, R. Cole, et al., ••Commissioning the GTA Accelerator," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR- 92-2716. D. P. Sandoval. R. C. Garcia, J. D. Gilpatrick, M. A. Shmas, R. Wright, V. Yuan, M. E. Zander, and K. F. Johnson, "Video Profile Monitor Diagnostic System for GTA," 1992 Linac Conference, Ottawa, Ontario, Canada, August 23-28, 1992, Los Alamos National Laboratory document LA-UR-92-2727. G. O. Bolme. P. M. Denney, W. D. Gutscher, S. P. Jachim, et al., "Analysis of High-Power Conditioning for Accelerator Cavities Using a Six-Port Reflectometer," 1992 Linac Conference, Ottawa, Ontario, Cp»vi?. August 23-28, 1992, Los Alamos National Laboratory document LA-UR-9"" ^.. ••> C. M. Frankle, J. D. Bowman, S. I. Penttila, S. J. Seestrom, S. H. Yoo, V. W. Yuan et al, "Measurement of Parity Violation in Compound Nuclear Resonances Using Epithermal Polarized Neutrons," to be published in NIM, Los Alamos National Laboratory document LA-UR-92-2740. J. D. Bowman and V.W. Yuan, "Measurement of Parity Violation in Compound Nuclear Resonances using Epithermal Polarized Neutrons," to be published in Nuclear Instruments and Methods, Los Alamos National Laboratory document LA- UR-92-2833. V.W. Yuan, R.C. Connolly, R.C. Garcia, K.F. Johnson, K. Saadatmand, O.R. Sander, D.P. Sandoval. and M.A. Shinas, "Measurement of Longitudinal Phase Space in an Accelerated H~ Beam Using a Laser-Induced Neutralization Method," to be published in Nuclear Instruments and Methods, Los Alamos National Labora- tory document LA-UR-92-2892. 126 Accelerator Technology Division Appendix A • Publications H. V. Smith, Jr., and P. Allison, "Electron Suppression in the H~ Beam from a Penning Surface-Plasma Source," to be published in Review of Scientific Instru- ments, Los Alamos National Laboratory document LA-UR-92-3337. J. D. Sherman, H. V. Smith, Jr., C. Geisik, and P. Allison, "H" Temperature Dependencies in a Penning Surface-Plasma Source," Neutral Particle Beam Technical Symposium, Argonne, IL, April 27-30, 1992, Los Alamos National Laboratory document LA-CP-92-217. E. A. Meyer, C. Bridgman, R. J. Grieggs, D. R. Schmittt, and J. D. Schneider, '"Improved Pulsed Gas Injection System for the GTA 4X Ion Source," Neutral Particle Beam Technical Symposium, Argonne, IL, April 27 - May 1, 1992, Los Alamos National Laboratory document LA-CP-92-227. L. B. Dauelsberg and C. Vigil, "Alignment Procedures for the GTA DTL Modules," Neutral Particle Beam Technical Symposium, Argonne, IL, April 27-30, 1992, Los Alamos National Laboratory document LA-CP-92-228. C. Geisik, D. R. Schmitt, J. D. Schneider, and J. E. Stelzer, "Computer System for the High Current Test Stand," Neutral Particle Beam Technical Symposium, Argonne, IL, April 27-30, 1992, Los Alamos National Laboratory document LA- CP-92-232. Accelerator Technology Division 127 Appendix B • Glossary ABC Accelerator Based Conversion AFEL advanced free-electron laser APEX APLE Prototype Experiment APLE Average Power Laser Experiment APS Advanced Photon Source APT Accelerator Production of Tritium ARES Advanced Research Electromagnetic Simulator AT-4 Acceleration Design and Engineering AT-5 RF Technology AT-7 Accelerator Theory & FEL Technology AT-8 Accelerator Controls and Automation ATW Accelerator Transmutation of Waste AXY A = high-power accelerator, XY=represent the specific application BCDTL bridge-coupled drift tube linac BEAR Beam Experiment Aboard a Rocket BESAC Basic Energy Sciences Advisory Committee BNL Brookhaven National Laboratory BOP balance of plant CAD computer aided design CAE computer aided engineering CCL coupled-cavity linac CCS cryogenic cooling system CEBAF Continuous Beam Accelerator Facility CERN European Center for Nuclear Research CLS-4 Photo Chemistry and Photo Physics CLS-6 Advanced Laser and Systems Technology CPU central processing unit CRADA Cooperative Research and Development Agreement CRL Chalk River Laboratory CTEN Combined Thermal/Epithermal Neutron cw continuous wave CWDD continuous wave deuterium demonstrator DARHT Dual-axis Radiographic Hydrodynamic Test dB decibel dc direct current DCM downconverter module DCN Document Change Notice DEWPOINT Directed Energy Weapons Power Integration DNA Defense Nuclear Agency DoD Department of Defense DOE Department of Energy DP Defense Programs dt drift tube DTL drift tube linac DTS discharge test stand ECAD electronic computer aided design EEV English Electric Valve EM electromagnetic EMP electromagnetic pulse EMQ electromagnet quadrupoles EMR electromagnetic radiation EPICS Experimental Physics and Industrial Control System 130 Accelerator Technology Division Appendix B • Glossary ERAB Energy Research Advisory Board ES&H Enviroment, safety, and health ESNIT Energy Selective Neutron Irradiation Test FEL free-electron laser FMIF Fusion Materials Irradiation Facility FOX far-field optics experiment FWBPM flying-wire beam-profile measurement FWHM full-width-at-half-maximum G gauss GAC Grumman Aerospace Corporation GFI ground fault interrupter GL gradient length GPR ground penetrating radar GTA Ground Test Accelerator HAM hybrid amplifier module HCTS high-current test stand HEBT high-energy beam transport HIBAF high-brightness accelerator FEL HIPERGPR high-performance ground penetrating radar HPCTB High-Power Cryogenic Test Bed HPM high-power microwave HPP high-pulse power HPRF high-power radio-frequency system I&C instrumentation and control ICN Integrated Computing Network IMS intermediate matching section INEL Idaho National Engineering Laboratory IOC input/output controller ITF Integrated Test Facility JAERI Japan Atomic Energy Research Institute LAACG Los Alamos Accelerator Code Group LAMPF Clinton P. Anderson Meson Physics Facility LANSCEII Manual Lujan, Jr. Neutron Scattering Center II LANSCE Manual Lujan, Jr. Neutron Scattering Center LBL Lawrence Berkeley Laboratory LDRD laboratory-directed research and development LEB low-energy booster LEBT low-energy beam transport LEP large electron positron collider LINDA laser induced neutralization diagnostics approach LLNL Lawrence Livermore National Laboratory LLRF low-level if LOG large orbit gyrotron LPCTB Low-Power Cryogenic Test Bed LVDT linear variable differential transducer MEBT moderate energy beam transport MMTW multiple-magnet taut-wire MP Medium Energy Physics Division MSDS Material Safety Data Sheet Accelerator Technology Division 131 Appendix B • Glossary MST-7 Materials Science and Technology: Polymers and Coatings NCLR National Center for Laser Research NCMS National Center for Manufacturing Sciences NERSC National Energy Research Supercomputer Center NLC Next Linear Collider NOP normal operating procedures NP New Production NPB neutral particle beam NPBSH neutral particle beam space experiment NSI National Security Information OFE Office of Fusion Energy ORNL Oak Ridge National Laboratory OTR optical-transition radiation P-15 Neutron Measurements Group PAC Particle Accelerator Conference PEIS Programmatic Environmental Impact Statement PET positron-emission tomography PIC particle-in-cell PID proportional, integral, and differential PMQ permanent-magnet quadrupole POP proof-of-principle PSII plasma source ion implantation PSR proton storage ring QA quality assurance R&D research and aevelopment RDBMS relational database management system rf radio frequency RFQ radio-frequency quadrupole RKA relativistic kylstron amplifier rms root-mean-square RPSS Radiation Protection Safety System RRR residual resistance ratio at 4K RSM3 rotating sample magnetic moment mapper SAIC Science Application International Corporation SAIS small angle ion source SC superconducting SCR silicon controlled rectifier SDIO Strategic Defense Initiative Organization SLAC Stanford Linear Accelerator Center SNL Sandia National Laboratories SNSI Secret National Security Information SOP standard operating procedures SRD Secret Restricted Data SSC Superconducting Super Collider SSCL Superconducting Super Collider Laboratory SST solid-state modes STATS Separations Technology and Transmutation Systems T temperature TTI Technology Transfer Initiative 132 Accelerator Technology Division Appendix B • Glossary UPM upconverter module USASDC United States Army Strategic Defense Command VDM vector detector module VFPMQ variable field permanent magnet quadrupole VLE vulnerability, lethality, and effects (VL&E) VME versa-rnodule European VXI VME External Interface VSWR voltage standing wave ratio WEC Westinghouse Electric Corporation WEMPE 4 wideband electromagnetic pulse environment X-1 Inertial Fusion and Plasma Theory XUV extreme ultraviolet * U.S. Government Printing Office 1993-774-208-93017 Accelerator Technology Division 133