Keyword: gun
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MOZE3 Emittance Measurements and Simulations from an X-Band Short-Pulse Ultra-High Gradient Photoinjector emittance, linac, simulation, laser 45
 
  • G. Chen, D.S. Doran, C.-J. Jing, S.Y. Kim, W. Liu, W. Liu, P. Piot, J.G. Power, C. Whiteford, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
  • C.-J. Jing, E.W. Knight, S.V. Kuzikov
    Euclid TechLabs, Solon, Ohio, USA
  • C.-J. Jing
    Euclid Beamlabs, Bolingbrook, USA
  • X. Lu, P. Piot, W.H. Tan
    Northern Illinois University, DeKalb, Illinois, USA
  
  Funding: This work is supported by the U.S. DOE, under award No. DE-SC0018656 to NIU, DOE SBIR grant No. DE-SC0018709 to Euclid Techlabs LLC, and contract No. DE-AC02-06CH11357 with ANL.
A pro­gram is under way at the Ar­gonne Wake­field Ac­cel­er­a­tor fa­cil­ity, in col­lab­o­ra­tion with the Eu­clid Tech­labs and North­ern Illi­nois Uni­ver­sity (NIU), to de­velop a GeV/m scale pho­to­cath­ode gun, with the ul­ti­mate goal of demon­strat­ing a high-bright­ness pho­toin­jec­tor beam­line. The novel X-band pho­toe­mis­sion gun (Xgun) is pow­ered by high-power, short RF pulses, 9-ns (FWHM), which, in turn, are gen­er­ated by the AWA drive beam. In a pre­vi­ous proof-of-prin­ci­ple ex­per­i­ment, an un­prece­dented 400~MV/m gra­di­ent on the pho­to­cath­ode sur­face* was demon­strated. In the cur­rent ver­sion of the ex­per­i­ment, we added a linac to the beam­line to in­crease the total en­ergy and gain ex­pe­ri­ence tun­ing the beam­line. In this paper, we re­port on the very first re­sult of emit­tance mea­sure­ment as well as sev­eral other beam pa­ra­me­ters. This pre­lim­i­nary in­ves­ti­ga­tion has iden­ti­fied sev­eral fac­tors to be im­proved on in order to achieve one of the ul­ti­mate goals; low emit­tance.
* W. H. Tan et al., "Demonstration of sub-GV/m Accelerating Field in a Photoemission Electron Gun Powered by Nanosecond X-Band Radiofrequency Pulses", 2022. arXiv:2203.11598v1 		 
slides icon Slides MOZE3 [5.565 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOZE3  
About • Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 14 August 2022
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MOPA13 Design of a Surrogate Model for MUED at BNL Using VSim, Elegant and HPC simulation, electron, detector, laser 72
 
  • S.I. Sosa Guitron, S. Biedron, T.B. Bolin
    UNM-ECE, Albuquerque, USA
  • S. Biedron
    Element Aero, Chicago, USA
  • S. Biedron
    UNM-ME, Albuquerque, New Mexico, USA
  
  Funding: U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Program of Electron and Scanning Probe Microscopes, award number DE-SC0021365.
The MeV Ul­tra­fast Elec­tron Dif­frac­tion (MUED) in­stru­ment at Brookhaven Na­tional Lab­o­ra­tory is a unique ca­pa­bil­ity for ma­te­r­ial sci­ence. As part of a plan to make MUED a high-through­put user fa­cil­ity, we are ex­plor­ing in­stru­men­ta­tion de­vel­op­ments based on Ma­chine Learn­ing (ML). We are de­vel­op­ing a sur­ro­gate model of MUED that can be used to sup­port con­trol tasks. The sur­ro­gate model will be based on beam sim­u­la­tions that are bench­marked to ex­per­i­men­tal ob­ser­va­tions. We use VSim to model the beam dy­nam­ics of the ra­dio-fre­quency gun and El­e­gant to trans­port the beam through the rest of the beam-line. We also use High Per­for­mance Com­put­ing re­sources from Ar­gonne Lead­er­ship Com­put­ing Fa­cil­ity to gen­er­ate the data for the sur­ro­gate model based on the orig­i­nal sim­u­la­tion as well as train­ing the ML model. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA13  
About • Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 21 August 2022
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MOPA85 Design of a 185.7 MHz Superconducting RF Photoinjector Quarter-Wave Resonator for the LCLS-II-HE Low Emittance Injector cavity, SRF, cathode, electron 245
 
  • S.H. Kim, W. Hartung, T. Konomi, S.J. Miller, M.S. Patil, J.T. Popielarski, K. Saito, T. Xu, T. Xu
    FRIB, East Lansing, Michigan, USA
  • C. Adolphsen, L. Ge, F. Ji, J.W. Lewellen, L. Xiao
    SLAC, Menlo Park, California, USA
  • M.P. Kelly, T.B. Petersen, P. Piot
    ANL, Lemont, Illinois, USA
  • P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  
  Funding: Work supported by the U.S. Department of Energy Contract DE-AC02-76SF00515.
A 185.7 MHz su­per­con­duct­ing quar­ter-wave res­onator (QWR) was de­signed for the low emit­tance in­jec­tor of the Linac Co­her­ent Light Source high en­ergy up­grade (LCLS-II-HE). The cav­ity was de­signed to min­i­mize the risk of cath­ode ef­fi­ciency degra­da­tion due to mul­ti­pact­ing or field emis­sion and to op­er­ate with a high RF elec­tric field at the cath­ode for low elec­tron-beam emit­tance. Cav­ity de­sign fea­tures in­clude: (1) shap­ing of the cav­ity wall to re­duce the strength of the low-field coax­ial mul­ti­pact­ing bar­rier; (2) four ports for elec­trop­o­l­ish­ing and high-pres­sure water rins­ing; and (3) a fun­da­men­tal power cou­pler (FPC) port lo­cated away from the ac­cel­er­at­ing gap. The de­sign is ori­ented to­ward min­i­miz­ing the risk of par­tic­u­late con­t­a­m­i­na­tion and avoid harm­ful di­pole com­po­nents in the RF field. The ANL 162 MHz FPC de­sign for PIP-II is being adapted for the gun cav­ity. We will pre­sent the RF de­sign of the cav­ity in­te­grated with the FPC. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA85  
About • Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 30 August 2022
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MOPA87 Design of the Cathode Stalk for the LCLS-II-HE Low Emittance Injector cathode, cavity, SRF, ISOL 253
 
  • T. Konomi, W. Hartung, S.H. Kim, S.J. Miller, D.G. Morris, J.T. Popielarski, K. Saito, A. Taylor, T. Xu
    FRIB, East Lansing, Michigan, USA
  • C. Adolphsen, J.W. Lewellen
    SLAC, Menlo Park, California, USA
  • S. Gatzmaga, P. Murcek, R. Xiang
    HZDR, Dresden, Germany
  • M.P. Kelly, T.B. Petersen
    ANL, Lemont, Illinois, USA
  
  Su­per­con­duct­ing ra­dio-fre­quency (SRF) elec­tron guns are at­trac­tive for de­liv­ery of beams at a high bunch rep­e­ti­tion rate with a high ac­cel­er­at­ing field. An SRF gun is the most suit­able in­jec­tor for the high-en­ergy up­grade of the Linac Co­her­ent Light Source (LCLS-II-HE), which will pro­duce high-en­ergy X-rays at high rep­e­ti­tion rate. An SRF gun is being de­vel­oped for LCLS-II-HE as a col­lab­o­ra­tive ef­fort by FRIB, HZDR, ANL, and SLAC. The cav­ity op­er­at­ing fre­quency is 185.7 MHz, and the tar­get ac­cel­er­at­ing field at the pho­to­cath­ode is 30 MV/m. The pho­to­cath­ode is re­place­able. The cath­ode is held by a fix­ture (’cath­ode stalk’) that is de­signed for ther­mal iso­la­tion and par­ti­cle-free cath­ode ex­change. The stalk must allow for pre­cise align­ment of the cath­ode po­si­tion, cryo­genic or room-tem­per­a­ture cath­ode op­er­at­ing tem­per­a­ture, and DC bias to in­hibit mul­ti­pact­ing. We are plan­ning a test of the stalk to con­firm that the de­sign meets the re­quire­ments for RF power dis­si­pa­tion and bi­as­ing. In this pre­sen­ta­tion, we will de­scribe the cath­ode stalk de­sign and RF/DC stalk test plan.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA87  
About • Received ※ 04 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 18 August 2022 — Issue date ※ 11 September 2022
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TUYD3 The Quest for the Perfect Cathode cathode, electron, emittance, photon 281
 
  • J.W. Lewellen, J. Smedley, T. Vecchione
    SLAC, Menlo Park, California, USA
  • D. Filippetto
    LBNL, Berkeley, California, USA
  • S.S. Karkare
    Arizona State University, Tempe, USA
  • J.M. Maxson
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • P. Musumeci
    UCLA, Los Angeles, California, USA
  
  Funding: U.S. Department of Energy.
The next gen­er­a­tion of free elec­tron lasers will be the first to see the per­for­mance of the laser strongly de­pen­dent on the ma­te­ri­als prop­er­ties of the pho­to­cath­ode. A new in­jec­tor pro­posed for the LCLS-II HE is an ex­am­ple of this rev­o­lu­tion, with the goal of in­creas­ing the pho­ton en­ergy achiev­able by LCLS-II to over 20 keV. We must now ask, what is the op­ti­mal cath­ode, tem­per­a­ture, and laser com­bi­na­tion to en­able this in­jec­tor? There are many com­pet­ing re­quire­ments. The cath­ode must be ro­bust enough to op­er­ate in a su­per­con­duct­ing in­jec­tor, and must not cause con­t­a­m­i­na­tion of the in­jec­tor. It must achieve suf­fi­cient charge at high rep­e­ti­tion rate, while min­i­miz­ing the emit­tance. The wave­length cho­sen must min­i­mize mean trans­verse en­ergy while main­tain­ing tol­er­a­ble lev­els of multi-pho­ton emis­sion. The cath­ode must be ca­pa­ble of op­er­at­ing at high (~30 MV/m) gra­di­ent, which puts lim­its on both sur­face rough­ness and field emis­sion. This pre­sen­ta­tion will dis­cuss the trade space for such a cath­ode/laser com­bi­na­tion, and de­tail a new col­lab­o­ra­tive pro­gram among a va­ri­ety of in­sti­tu­tions to in­ves­ti­gate it. 		 
slides icon Slides TUYD3 [1.632 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD3  
About • Received ※ 02 August 2022 — Revised ※ 04 August 2022 — Accepted ※ 14 August 2022 — Issue date ※ 26 September 2022
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TUYD6 Design of a 200 kV DC Cryocooled Photoemission Gun for Photocathode Investigations cathode, electron, MMI, cryogenics 292
 
  • G.S. Gevorkyan, T.J. Hanks, A.H. Kachwala, S.S. Karkare, C.J. Knill, C.A. Sarabia Cardenas
    Arizona State University, Tempe, USA
  
  Funding: This work was supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams, and the DOE under Grant No. DE-SC0021092.
We pre­sent the first re­sults of the com­mis­sion­ing of the 200 kV DC elec­tron gun with a cryo­geni­cally cooled cath­ode at Ari­zona State Uni­ver­sity. The gun is specif­i­cally de­signed for study­ing a wide va­ri­ety of novel cath­ode ma­te­ri­als in­clud­ing sin­gle crys­talline and epi­tax­i­ally grown ma­te­ri­als at 30 K tem­per­a­tures to ob­tain the low­est pos­si­ble in­trin­sic emit­tance of UED and XFEL ap­pli­ca­tions [1]. We will pre­sent the mea­sure­ments of the cryo­genic per­for­mance of the gun and the first high volt­age com­mis­sion­ing re­sults.
[1] G. S. Gevorkyan et. al., Proc. of NAPAC19 MOPLM16 (2019) 		 
slides icon Slides TUYD6 [12.632 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUYD6  
About • Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 29 September 2022
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TUZE5 Studies of Ion Beam Heating by Electron Beams electron, emittance, experiment, solenoid 343
 
  • S. Seletskiy, A.V. Fedotov, D. Kayran
    BNL, Upton, New York, USA
  
  Pres­ence of an elec­tron beam cre­ated by ei­ther elec­tron cool­ers or elec­tron lenses in an ion stor­age ring is as­so­ci­ated with an un­wanted emit­tance growth (heat­ing) of the ion bunches. In this paper we re­port ex­per­i­men­tal stud­ies of the elec­tron-ion heat­ing in the Low En­ergy RHIC elec­tron Cooler (LEReC).  
slides icon Slides TUZE5 [1.368 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUZE5  
About • Received ※ 01 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 17 September 2022
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TUPA34 Model-Based Calibration of Control Parameters at the Argonne Wakefield Accelerator network, controls, simulation, wakefield 427
 
  • I.P. Sugrue, B. Mustapha, P. Piot, J.G. Power
    ANL, Lemont, Illinois, USA
  • N. Krislock
    Northern Illinois University, DeKalb, Illinois, USA
  
  Par­ti­cle ac­cel­er­a­tors uti­lize a large num­ber of con­trol pa­ra­me­ters to gen­er­ate and ma­nip­u­late beams. Dig­i­tal mod­els and sim­u­la­tions are often used to find the best op­er­at­ing pa­ra­me­ters to achieve a set of given beam pa­ra­me­ters. Un­for­tu­nately, the op­ti­mized physics pa­ra­me­ters can­not pre­cisely be set in the con­trol sys­tem due to, e.g., cal­i­bra­tion un­cer­tain­ties. We de­vel­oped a data-dri­ven physics-in­formed sur­ro­gate model using neural net­works to re­place dig­i­tal mod­els re­ly­ing on beam-dy­nam­ics sim­u­la­tions. This sur­ro­gate model can then be used to per­form quick di­ag­nos­tics of the Ar­gonne Wake­field ac­cel­er­a­tor in real time using non­lin­ear least-squares meth­ods to find the most likely op­er­at­ing pa­ra­me­ters given a mea­sured beam dis­tri­b­u­tion.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA34  
About • Received ※ 05 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 24 September 2022
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TUPA36 The Advanced Photon Source Linac Extension Area Beamline electron, linac, photon, lattice 430
 
  • K.P. Wootton, W. Berg, J.M. Byrd, J.C. Dooling, G.I. Fystro, A.H. Lumpkin, Y. Sun, A. Zholents
    ANL, Lemont, Illinois, USA
  • C.C. Hall
    RadiaSoft LLC, Boulder, Colorado, USA
  
  Funding: This research used resources of the Advanced Photon Source, operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
The Linac Ex­ten­sion Area at the Ad­vanced Pho­ton Source is a flex­i­ble beam­line area for test­ing ac­cel­er­a­tor com­po­nents and tech­niques. Dri­ven by the Ad­vanced Pho­ton Source elec­tron linac equipped with a pho­to­cath­ode RF elec­tron gun, the Linac Ex­ten­sion Area houses a 12 m long beam­line. The beam­line is fur­nished with YAG screens, BPMs and a mag­netic spec­trom­e­ter to as­sist with char­ac­ter­i­za­tion of beam emit­tance and en­ergy spread. A 1.4 m long in­ser­tion in the mid­dle of the beam­line is pro­vided for the in­stal­la­tion of a de­vice under test. The beam­line is ex­pected to be avail­able soon for test­ing ac­cel­er­a­tor com­po­nents and tech­niques using round and flat elec­tron beams over an en­ergy range 150-450 MeV. In the pre­sent work, we de­scribe this beam­line and sum­marise the main beam pa­ra­me­ters. 		 
poster icon Poster TUPA36 [0.892 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA36  
About • Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 19 September 2022
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TUPA73 Design and Low Power Test of an Electron Bunching Enhancer Using Electrostatic Potential Depression cavity, electron, simulation, experiment 499
 
  • H. Xu, B.E. Carlsten, Q.R. Marksteiner
    LANL, Los Alamos, New Mexico, USA
  • B.L. Beaudoin, T.W. Koeth, A. Ting
    UMD, College Park, Maryland, USA
  
  Funding: This project was supported by the U.S. Department of Energy Office of Science through the Accelerator Stewardship Program.
We pre­sent our ex­per­i­men­tal de­sign and low power test re­sults of a struc­ture for the proof-of-prin­ci­ple demon­stra­tion of fast in­crease of the first har­monic cur­rent con­tent in a bunched elec­tron beam, using the tech­nique of elec­tro­sta­tic po­ten­tial de­pres­sion (EPD). A pri­mar­ily bunched elec­tron beam from an in­duc­tive out­put tube (IOT) at 710 MHz first en­ters an idler cav­ity, where the lon­gi­tu­di­nal slope of the beam en­ergy dis­tri­b­u­tion is re­versed. The beam then tran­sits through an EPD sec­tion im­ple­mented by a short beam pipe with a neg­a­tive high volt­age bias, in­side which the rate of in­crease of the first har­monic cur­rent is sig­nif­i­cantly en­hanced. An out­put cav­ity mea­sures the har­monic cur­rent de­vel­oped in­side the beam down­stream of the EPD sec­tion. Low power test re­sults of the idler and the out­put cav­i­ties agree with the the­o­ret­i­cal de­sign. 		 
poster icon Poster TUPA73 [1.307 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA73  
About • Received ※ 29 July 2022 — Accepted ※ 03 August 2022 — Issue date ※ 09 August 2022  
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TUPA77 X-Band Harmonic Longitudinal Phase Space Linearization at the PEGASUS Photoinjector cavity, linac, electron, laser 508
 
  • P.E. Denham, P. Musumeci, A. Ody
    UCLA, Los Angeles, USA
  
  Due to the fi­nite bunch length, pho­toemit­ted elec­tron beams sam­ple RF-non­lin­ear­i­ties that lead to en­ergy-time cor­re­la­tions along the bunch tem­po­ral pro­file. This is an im­por­tant ef­fect for all ap­pli­ca­tions where the pro­jected en­ergy spread is im­por­tant. In par­tic­u­lar, for time-re­solved sin­gle shot elec­tron mi­croscopy, it is crit­i­cal to keep the beam en­ergy spread below 1·10-4 to avoid chro­matic aber­ra­tions in the lenses. Higher har­monic RF cav­i­ties can be used to com­pen­sate for the RF-in­duced lon­gi­tu­di­nal phase space non­lin­ear­i­ties. Start-to-end sim­u­la­tions sug­gest that this type of com­pen­sa­tion can re­duce en­ergy spread to the 1·10-5 level. This work is an ex­per­i­men­tal study of x-band har­monic lin­eariza­tion of a beam lon­gi­tu­di­nal phase space at the PE­GA­SUS fa­cil­ity, in­clud­ing de­vel­op­ing high-res­o­lu­tion spec­trom­e­ter di­ag­nos­tics to ver­ify the scheme.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA77  
About • Received ※ 25 July 2022 — Revised ※ 04 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 10 August 2022
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TUPA80 Cyborg Beamline Development Updates cathode, cavity, cryogenics, simulation 512
 
  • G.E. Lawler, A. Fukasawa, N. Majernik, J.R. Parsons, J.B. Rosenzweig, Y. Sakai
    UCLA, Los Angeles, California, USA
  • F. Bosco
    Sapienza University of Rome, Rome, Italy
  • Z. Li, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  • B. Spataro
    LNF-INFN, Frascati, Italy
  
  Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE Contract DE-SC0020409.
Xray free elec­tron laser (XFEL) fa­cil­i­ties in their cur­rent form are large, costly to main­tain, and in­ac­ces­si­ble due to their min­i­mal sup­ply and high de­mand. It is then ad­van­ta­geous to con­sider minia­tur­iz­ing XFELs through a va­ri­ety of means. We hope to in­crease beam bright­ness from the pho­toin­jec­tor via high gra­di­ent op­er­a­tion (>120 MV/m) and cryo­genic tem­per­a­ture op­er­a­tion at the cath­ode (<77K). To this end we have de­signed and fab­ri­cated our new CrYo­genic Bright­ness-Op­ti­mized Ra­diofre­quency Gun (CY­B­GORG). The pho­to­gun is 0.5 cell so much less com­pli­cated than our even­tual 1.6 cell pho­toin­jec­tor. It will serve as a pro­to­type and test bed for cath­ode stud­ies in a new cryo­genic and very high gra­di­ent regime. We pre­sent here the fab­ri­cated struc­ture, progress to­wards com­mis­sion­ing, and beam­line sim­u­la­tions. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-TUPA80  
About • Received ※ 02 August 2022 — Accepted ※ 06 August 2022 — Issue date ※ 09 October 2022  
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WEXD5 Benchmarking Simulation for AWA Drive Linac and Emittance Exchange Beamline Using OPAL, GPT, and Impact-T simulation, emittance, linac, solenoid 552
 
  • S.Y. Kim, G. Chen, D.S. Doran, G. Ha, W. Liu, J.G. Power, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
  • E.A. Frame, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  
  At the Ar­gonne Wake­field Ac­cel­er­a­tor (AWA) fa­cil­ity, par­ti­cle-track­ing sim­u­la­tions have been crit­i­cal to guid­ing beam-dy­namic ex­per­i­ments, e.g., for var­i­ous beam ma­nip­u­la­tions using an avail­able emit­tance-ex­change beam­line (EEX). The unique beam­line avail­able at AWA pro­vide a test case to per­form in-depth com­par­i­son be­tween dif­fer­ent par­ti­cle-track­ing pro­grams in­clud­ing col­lec­tive ef­fects such as space-charge force and co­her­ent syn­chro­tron ra­di­a­tion. In this study, using AWA elec­tron in­jec­tor and emit­tance ex­change beam­line, we com­pare the sim­u­la­tions re­sults ob­tained by GPT, OPAL, and Im­pact-T beam-dy­nam­ics pro­grams. We will specif­i­cally re­port on con­ver­gence test as a func­tion of pa­ra­me­ters that con­trols the un­der­ly­ing al­go­rithms.  
slides icon Slides WEXD5 [1.847 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEXD5  
About • Received ※ 03 August 2022 — Revised ※ 06 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 22 August 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEZE3 Compact, High-Power Superconducting Electron Linear Accelerators for MW Industrial Applications cavity, electron, SRF, vacuum 604
 
  • J.C.T. Thangaraj, R. Dhuley
    Fermilab, Batavia, Illinois, USA
  
  Fer­mi­lab has de­vel­oped a novel con­cept for an in­dus­trial elec­tron linac using Nb3Sn coat­ing tech­nol­ogy and con­duc­tion cool­ing. We will show the range of multi-cav­ity linac de­signs tar­geted to­ward var­i­ous ap­pli­ca­tions. We will also dis­cuss tech­nol­ogy de­vel­op­ment sta­tus with re­sults on con­duc­tion cool­ing of SRF cav­i­ties based on cry­ocool­ers, which re­moves the need for liq­uid He­lium, thus mak­ing SRF tech­nol­ogy ac­ces­si­ble to in­dus­trial ap­pli­ca­tions. These con­duc­tion-cooled linacs can gen­er­ate elec­tron beam en­er­gies up to 10 MeV in con­tin­u­ous-wave op­er­a­tion and can reach higher power (>=1 MW) by comb­ing sev­eral mod­ules. Com­pact and light enough to mount on mo­bile plat­forms, our ma­chine is an­tic­i­pated to en­able new in-situ en­vi­ron­men­tal re­me­di­a­tion ap­pli­ca­tions such as waste-wa­ter treat­ment for urban areas, X-ray med­ical de­vice ster­il­iza­tion, and in­no­v­a­tive pave­ment ap­pli­ca­tions. We also show cost-eco­nom­ics and key R&D areas that much be ad­dressed for a prac­ti­cal ma­chine.  
slides icon Slides WEZE3 [3.811 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZE3  
About • Received ※ 02 August 2022 — Revised ※ 12 August 2022 — Accepted ※ 13 August 2022 — Issue date ※ 30 August 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEZE4 First High-Gradient Results of UED/UEM SRF Gun at Cryogenic Temperatures cavity, SRF, accelerating-gradient, cryogenics 607
 
  • R.A. Kostin, C. Jing
    Euclid Beamlabs, Bolingbrook, USA
  • D.J. Bice, T.N. Khabiboulline, S. Posen
    Fermilab, Batavia, Illinois, USA
  
  Funding: The project is funded by DOE SBIR #DE-SC0018621
Ben­e­fit­ing from the rapid progress on RF pho­to­gun tech­nolo­gies in the past two decades, the de­vel­op­ment of MeV range ul­tra­fast elec­tron dif­frac­tion/mi­croscopy (UED and UEM) has been iden­ti­fied as an en­abling in­stru­men­ta­tion. UEM or UED use low power elec­tron beams with mod­est en­er­gies of a few MeV to study ul­tra­fast phe­nom­ena in a va­ri­ety of novel and ex­otic ma­te­ri­als. SRF pho­to­guns be­come a promis­ing can­di­date to pro­duce highly sta­ble elec­trons for UEM/UED ap­pli­ca­tions be­cause of the ul­tra­high shot-to-shot sta­bil­ity com­pared to room tem­per­a­ture RF pho­to­guns. SRF tech­nol­ogy was pro­hib­i­tively ex­pen­sive for in­dus­trial use until two re­cent ad­vance­ments: Nb3Sn and con­duc­tion cool­ing. The use of Nb3Sn al­lows to op­er­ate SRF cav­i­ties at higher tem­per­a­tures (4K) with low power dis­si­pa­tion which is within the reach of com­mer­cially avail­able closed-cy­cle cry­ocool­ers. Eu­clid is de­vel­op­ing a con­tin­u­ous wave (CW), 1.5-cell, MeV-scale SRF con­duc­tion cooled pho­to­gun op­er­at­ing at 1.3 GHz. In this paper, we pre­sent first high gra­di­ent re­sults of the gun con­ducted in liq­uid he­lium. 		 
slides icon Slides WEZE4 [2.817 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZE4  
About • Received ※ 05 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 29 September 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPA01 Beam Dynamics Optimization of a Low Emittance Photoinjector Without Buncher Cavities emittance, cavity, electron, cathode 615
 
  • J. Qiang
    LBNL, Berkeley, California, USA
  • F. Ji, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  
  The pho­toin­jec­tor plays an im­por­tant role in gen­er­at­ing high bright­ness low emit­tance elec­tron beam for x-ray free elec­tron laser ap­pli­ca­tions. In this paper, we re­port on beam dy­nam­ics op­ti­miza­tion study of a low emit­tance pho­toin­jec­tor based on a pro­posed su­per­con­duct­ing gun with­out in­clud­ing any buncher cav­i­ties. Multi-ob­jec­tive op­ti­miza­tion with self-con­sis­tent beam dy­nam­ics sim­u­la­tions was em­ployed to at­tain the op­ti­mal Pareto front.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA01  
About • Received ※ 02 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 11 September 2022
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WEPA02 Beam Dynamics Studies on a Low Emittance Injector for LCLS-II-HE emittance, cathode, solenoid, cavity 619
 
  • F. Ji, C. Adolphsen, R. Coy, L. Ge, C.E. Mayes, T.O. Raubenheimer, L. Xiao
    SLAC, Menlo Park, California, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
  
  The SLAC High En­ergy up­grade of LCLS-II (LCLS-II-HE) will dou­ble the beam en­ergy to 8 GeV, in­creas­ing the XFEL pho­ton en­ergy reach to about 13 keV. The en­ergy reach can be ex­tended to 20 keV if the beam emit­tance can be halved, which re­quires a higher gra­di­ent elec­tron gun with a lower in­trin­sic emit­tance pho­to­cath­ode. To this end, the Low Emit­tance In­jec­tor (LEI) will be built that will run par­al­lel to the ex­ist­ing LCLS-II In­jec­tor. The LEI de­sign will be based on a state-of-the-art SRF gun with a 30 MV/m cath­ode gra­di­ent. The main goal is to pro­duce trans­verse beam emit­tances of 0.1 mm-mrad for 100 pC bunch charges. This paper de­scribes the beam dy­nam­ics stud­ies on the de­sign of the LEI in­clud­ing the sim­u­la­tions and multi-ob­jec­tive ge­netic al­go­rithm (MOGA) op­ti­miza­tions. Per­for­mance with dif­fer­ent in­jec­tor lay­outs, cath­ode gra­di­ents, bunch charges and cath­ode mean trans­verse en­er­gies (MTEs) will be pre­sented.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA02  
About • Received ※ 02 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 17 August 2022
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WEPA03 Status of the SLAC/MSU SRF Gun Development Project cathode, cavity, SRF, cryomodule 623
 
  • J.W. Lewellen, C. Adolphsen, R. Coy, L. Ge, F. Ji, M.J. Murphy, L. Xiao
    SLAC, Menlo Park, California, USA
  • A. Arnold, S. Gatzmaga, P. Murcek, R. Xiang
    HZDR, Dresden, Germany
  • Y. Choi, C. Compton, X.-J. Du, D.B. Greene, W. Hartung, S.H. Kim, T. Konomi, S.J. Miller, D.G. Morris, M.S. Patil, J.T. Popielarski, L. Popielarski, K. Saito, T. Xu
    FRIB, East Lansing, Michigan, USA
  • M.P. Kelly, T.B. Petersen
    ANL, Lemont, Illinois, USA
  
  Funding: US Department of Energy.
The LCLS-II-HE pro­ject at SLAC is in­tended to in­crease the pho­ton en­ergy reach of the LCLS-II FEL to at least 20 keV. In ad­di­tion to up­grad­ing the un­du­la­tor sys­tem, and in­creas­ing the elec­tron beam en­ergy to 8 GeV, the pro­ject will also con­struct a low-emit­tance in­jec­tor (LEI) in a new tun­nel. To achieve the LEI emit­tance goals, a low-MTE pho­to­cath­ode will be re­quired, as will on-cath­ode elec­tric fields up to 50% higher than those achiev­able in the cur­rent LCLS-II pho­toin­jec­tor. The beam source for the LEI will be based around a su­per­con­duct­ing quar­ter­wave cav­ity res­o­nant at 185.7 MHz. A pro­to­type gun is cur­rently being de­signed and fab­ri­cated at the Fa­cil­ity for Rare Iso­tope Beams (FRIB) at Michi­gan State Uni­ver­sity. This paper pre­sents the per­for­mance goals for the new gun de­sign, an overview of the pro­to­type de­vel­op­ment ef­fort, cur­rent sta­tus, and fu­ture plans in­clud­ing fab­ri­ca­tion of a "pro­duc­tion" gun for the LEI. 		 
poster icon Poster WEPA03 [4.510 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA03  
About • Received ※ 21 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 11 August 2022
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WEPA08 Design and Operation Experience of a Multi-Collimator/YAG Screen Device on LCLS II Low Energy Beamline wakefield, simulation, radiation, electron 631
 
  • X. Liu, C. Adolphsen, M. Santana-Leitner, L. Xiao, F. Zhou
    SLAC, Menlo Park, California, USA
  
  Dur­ing the com­mis­sion­ing of the nor­mal con­duct­ing VHF RF gun of LCLS II, it was ob­served that field emis­sion (dark cur­rent) of roughly 2 µA level was pre­sent under nor­mal op­er­a­tion of the gun. While the dark cur­rent of this level is deemed man­age­able with ex­ist­ing beam­line con­fig­u­ra­tions, it is de­sired in pre­cau­tion to add a col­li­ma­tor on the low en­ergy beam­line to block the dark cur­rent, being con­cerned that the dark cur­rent sit­u­a­tion might worsen with time. Since no spare lon­gi­tu­di­nal space is avail­able, the new de­vice takes place of the ex­ist­ing YAG screen. The new de­vice is made of a 15 mm thick cop­per plate, with four round aper­tures of 6, 8, 10, and 12 mm ra­dius re­spec­tively. At the end of the col­li­ma­tor plate, fea­tures are made for clamp­ing two YAG screens and mount­ing their cor­re­spond­ing mir­rors for beam/halo pro­file imag­ing. The col­li­ma­tor plate is elec­tri­cally in­su­lated from the cham­ber so that it can also be used for mea­sur­ing the dark cur­rent. A mo­tor-dri­ven UHV com­pat­i­ble lin­ear trans­la­tor shifts the de­vice be­tween po­si­tions. Be­sides de­sign de­tails, re­lated ther­mal, beam dy­nam­ics, and ra­di­a­tion analy­ses as well as op­er­a­tion ex­pe­ri­ence will be pre­sented.

* Work supported by US DOE under contract AC02-76SF00515. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA08  
About • Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 13 September 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPA09 A Parallel Automatic Simulation Tool for Cavity Shape Optimization cavity, HOM, simulation, SRF 634
 
  • L. Ge, Z. Li, C.-K. Ng, L. Xiao
    SLAC, Menlo Park, California, USA
  • M. Beall, B.R. Downie, O. Klaas
    Simmetrix Inc., Clifton Park, USA
  
  Funding: U.S. Department of Energy under contract No. DE-SC0018715.
We pre­sent a par­al­lel au­to­matic shape op­ti­miza­tion work­flow for de­sign­ing ac­cel­er­a­tor cav­i­ties. The newly de­vel­oped 3D par­al­lel op­ti­miza­tion tool Opt3P based on dis­crete ad­joint meth­ods is used to de­ter­mine the op­ti­mal ac­cel­er­a­tor cav­ity shape with the de­sired spec­tral re­sponse. Ini­tial and up­dated mod­els, meshes, and de­sign ve­loc­i­ties of de­sign pa­ra­me­ters for defin­ing the cav­ity shape are gen­er­ated with Sim­metrix tools for mesh gen­er­a­tion (Mesh­Sim), geom­e­try mod­i­fi­ca­tion and query (Ge­om­Sim), and user in­ter­face tools (Sim­Mod­eler). Two shape op­ti­miza­tion ex­am­ples using this au­to­matic sim­u­la­tion work­flow will be pre­sented here. One is the TESLA cav­ity with higher-or­der-mode (HOM) cou­plers and the other is a su­per­con­duct­ing rf (SRF) gun. The ob­jec­tive for the TESLA cav­ity is to min­i­mize HOM damp­ing fac­tors and for the SRF gun to min­i­mize the sur­face elec­tric and mag­netic fields while main­tain­ing its op­er­at­ing mode fre­quency at a pre­scribed value. The re­sults demon­strate that the au­to­matic sim­u­la­tion tool al­lows an ef­fi­cient shape op­ti­miza­tion pro­ce­dure with min­i­mal man­ual op­er­a­tions. All sim­u­la­tions were per­formed on the NERSC su­per­com­puter Cori sys­tem for so­lu­tion speedup. 		 
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA09  
About • Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 09 August 2022 — Issue date ※ 08 October 2022
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WEPA10 Determination of LCLS-II Gun-2 Prototype Dimensions cavity, cathode, simulation, vacuum 637
 
  • L. Xiao, C. Adolphsen, E.N. Jongewaard, X. Liu, F. Zhou
    SLAC, Menlo Park, California, USA
  
  The LCLS-II spare gun (Gun-2) de­sign is largely based on the ex­ist­ing LCLS-II gun (Gun-1), in which there is sig­nif­i­cant cap­tured dark cur­rent (DC) that orig­i­nates on the high field cop­per sur­face near the cath­ode plug gap open­ing. To help sup­press DC, the Gun-2 cath­ode and anode noses and the cath­ode plug open­ing are el­lip­ti­cally shaped to min­i­mize the peak sur­face field for a given cath­ode gra­di­ent. Stain­less steel (SS) cath­ode and anode in­serts are used in Gun-2 to fur­ther re­duce dark cur­rent. The RF sim­u­la­tions were per­formed using a model that in­cludes all the 3D fea­tures. The ther­mal and struc­tural analy­ses were done to in­ves­ti­gate the ef­fects of the air pres­sure and RF heat­ing. The multi-physics sim­u­la­tion re­sults pro­vided the in­for­ma­tion needed to com­pute the over­all fre­quency change from the basic 2D model to the nom­i­nal fre­quency dur­ing op­er­a­tion. The Gun-2 cath­ode-to-an­ode gap dis­tance will be made 1 mm longer than the nom­i­nal gap with the ex­pec­ta­tion that less than 1 mm will be ma­chined off to meet the tar­get fre­quency. In this paper, the Gun-2 fre­quency cor­rec­tion cal­cu­la­tions are pre­sented, and the cath­ode-to-an­ode gap de­ter­mi­na­tion is dis­cussed.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA10  
About • Received ※ 30 July 2022 — Revised ※ 03 August 2022 — Accepted ※ 08 August 2022 — Issue date ※ 10 August 2022
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WEPA13 New Results at JLab Describing Operating Lifetime of GaAs Photo-guns cathode, electron, laser, experiment 644
 
  • M.W. Bruker, J.M. Grames, C. Hernandez-Garcia, M. Poelker, S. Zhang
    JLab, Newport News, Virginia, USA
  • V.M. Lizárraga-Rubio, C.A. Valerio-Lizárraga
    ECFM-UAS, Culiacan, Sinaloa, Mexico
  • J.T. Yoskowitz
    ODU, Norfolk, Virginia, USA
  
  Funding: This work is supported by U.S. Department of Energy under DE-AC05-06OR23177 and by Consejo Nacional de Ciencia y Tecnología and the Universidad Autonoma de Sinaloa under PRO_A1_022.
Po­lar­ized elec­trons from GaAs pho­to­cath­odes have been key to some of the high­est-im­pact re­sults of the Jef­fer­son Lab sci­ence pro­gram over the past 30 years. Dur­ing this time, var­i­ous stud­ies have given in­sight into im­prov­ing the op­er­a­tional life­time of these pho­to­cath­odes in DC high-volt­age photo-guns while using lasers with spa­tial Gauss­ian pro­files of typ­i­cally 0.5 mm to 1 mm FWHM, cath­ode volt­ages of 100 kV to 130 kV, and a wide range of beam cur­rents up to mul­ti­ple mA. In this con­tri­bu­tion, we show re­cent ex­per­i­men­tal data from a 100 kV to 180 kV setup and de­scribe our progress at pre­dict­ing the life­time based on the cal­cu­la­ble dy­nam­ics of ion­ized gas mol­e­cules in­side the gun. These new ex­per­i­men­tal stud­ies at Jef­fer­son Lab are specif­i­cally aimed at ex­plor­ing the ion dam­age of higher-volt­age guns being built for in­jec­tors. 		 
poster icon Poster WEPA13 [1.644 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA13  
About • Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 01 October 2022
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WEPA16 A 500 kV Inverted Geometry Feedthrough for a High Voltage DC Electron Gun high-voltage, electron, power-supply, cathode 651
 
  • C. Hernandez-Garcia, D.B. Bullard, J.M. Grames, G.G. Palacios Serrano, M. Poelker
    JLab, Newport News, Virginia, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Office of Science Funding Opportunity LAB 20-2310 award PAMS-254442.
The Con­tin­u­ous Elec­tron Beam Ac­cel­er­a­tor Fa­cil­ity in­jec­tor at Jef­fer­son Lab (JLab) uti­lizes an in­verted-geom­e­try ce­ramic in­su­la­tor pho­to­gun op­er­at­ing at 130 kV di­rect cur­rent to gen­er­ate spin-po­lar­ized elec­tron beams for high-en­ergy nu­clear physics ex­per­i­ments. A sec­ond pho­to­gun de­liv­ers 180 keV beam for com­mis­sion­ing a SRF booster in a test­bed ac­cel­er­a­tor, and a larger ver­sion de­liv­ers 300 keV mag­ne­tized beam in a test stand beam line. This con­tri­bu­tion re­ports on the de­vel­op­ment of an un­prece­dented in­verted-in­su­la­tor with cable con­nec­tor for re­li­ably ap­ply­ing 500 kV DC to a fu­ture po­lar­ized beam pho­to­gun, to be de­signed for op­er­at­ing at 350 kV with­out field emis­sion. Such a pho­to­gun de­sign could then be used for gen­er­at­ing a po­lar­ized elec­tron beam to drive a spin-po­lar­ized positron source as a demon­stra­tor for high en­ergy nu­clear physics at JLab. There are no com­mer­cial cable con­nec­tors that fit the large in­verted in­su­la­tors re­quired for that volt­age range. Our pro­posed con­cept is based on a mod­i­fied epoxy re­cep­ta­cle with in­ter­ven­ing SF6 layer and a test elec­trode in a vac­uum ves­sel. 		 
poster icon Poster WEPA16 [6.217 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA16  
About • Received ※ 03 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 07 August 2022 — Issue date ※ 09 October 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPA17 Improved Electrostatic Design of the Jefferson Lab 300 kV DC Photogun and the Minimization of Beam Deflection cathode, electron, high-voltage, laser 655
 
  • M.A. Mamun, D.B. Bullard, J.M. Grames, C. Hernandez-Garcia, G.A. Krafft, M. Poelker, R. Suleiman
    JLab, Newport News, Virginia, USA
  • J.R. Delayen, G.A. Krafft, G.G. Palacios Serrano, S.A.K. Wijethunga
    ODU, Norfolk, Virginia, USA
  
  Funding: This work is supported by the Department of Energy, under contract DE-AC05-06OR23177, JSA initiatives fund program, and the Laboratory Directed Research and Development program.
An elec­tron beam with high bunch charge and high rep­e­ti­tion rate is re­quired for elec­tron cool­ing of the ion beam to achieve the high lu­mi­nos­ity re­quired for the pro­posed elec­tron-ion col­lid­ers. An im­proved de­sign of the 300 kV DC high volt­age pho­to­gun at Jef­fer­son Lab was in­cor­po­rated to­ward over­com­ing the beam loss and space charge cur­rent lim­i­ta­tion ex­pe­ri­enced in the orig­i­nal de­sign. To reach the bunch charge goal of ~ few nC within 75 ps bunches, the ex­ist­ing DC high volt­age pho­to­gun elec­trodes and an­ode-cath­ode gap were mod­i­fied to in­crease the lon­gi­tu­di­nal elec­tric field (Ez) at the pho­to­cath­ode. The an­ode-cath­ode gap was re­duced to in­crease the Ez at the pho­to­cath­ode, and the anode aper­ture was spa­tially shifted with re­spect to the beam­line lon­gi­tu­di­nal axis to min­i­mize the beam de­flec­tion in­tro­duced by the geo­met­ric asym­me­try of the in­verted in­su­la­tor pho­to­gun. The elec­tro­sta­tic de­sign and beam dy­nam­ics sim­u­la­tions were per­formed to de­ter­mine the re­quired mod­i­fi­ca­tion. Beam-based mea­sure­ment from the mod­i­fied gun con­firmed the re­duc­tion of the beam de­flec­tion, which is pre­sented in this con­tri­bu­tion. 		 
poster icon Poster WEPA17 [2.973 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA17  
About • Received ※ 23 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 05 August 2022 — Issue date ※ 11 August 2022
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WEPA20 High-Gradient Wien Spin Rotators at Jefferson Lab vacuum, electron, operation, high-voltage 662
 
  • G.G. Palacios Serrano, P.A. Adderley, J.M. Grames, C. Hernandez-Garcia, M. Poelker
    JLab, Newport News, Virginia, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Nu­clear physics ex­per­i­ments per­formed in the Con­tin-uous Elec­tron Beam Ac­cel­er­a­tor Fa­cil­ity (CEBAF) at Jef­fer­son Lab­o­ra­tory (JLab) re­quire spin ma­nip­u­la­tion of elec­tron beams. Two Wien spin ro­ta­tors in the in­jec­tor keV re­gion are es­sen­tial at CEBAF to es­tab­lish lon­gi­tu­di­nal po­lar­iza­tion at the end sta­tion tar­get, and to flip the po­lar­iza­tion di­rec­tion by π rad to rule out false asym­me­tries. In a Wien fil­ter, the ho­mo­ge­neous and in­de­pen­dent elec­tric and mag­netic fields, along with the ve­loc­ity vec­tors of the elec­trons that tra­verse it, form a mu­tu­ally or­thog­o­nal sys­tem. The mag­ni­tude of the elec­tro­sta­tic field, es­tab­lished by bi­as­ing two highly-pol­ished elec-trodes, de­fines the de­sired spin angle at the tar­get yet de­vi­ates the beam tra­jec­tory due to the Lorentz force. The beam tra­jec­tory in the Wien is then re-es­tab­lished by ad­just­ing the mag­netic field, in­duced by an elec­tro­mag-net en­cas­ing the de­vice vac­uum cham­ber. This con­tribu-tion de­scribes the evo­lu­tion de­sign and high volt­age test­ing of Wien fil­ters for spin ma­nip­u­la­tion at in­creased beam en­er­gies in the keV in­jec­tor re­gion, re­quired by high pre­ci­sion par­ity vi­o­la­tion ex­per­i­ments like MOLLER. 		 
poster icon Poster WEPA20 [1.434 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA20  
About • Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 05 September 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPA41 Maximizing Output of 3 MeV S-band Industrial Accelerator target, ECR, simulation, high-voltage 723
 
  • D. Fischer, M. Denney, A.V. Mishin, S. Proskin, J. Roylance, L. Young
    Varex Imaging, Salt Lake City, USA
  
  Ear­lier, we have re­ported on a record-break­ing 3-MeV Ac­cel­er­a­tor Beam Cen­ter­line (ABC) built in 2017-2018. An up­graded ver­sion of this 3-MeV S-band ABC has been de­vel­oped at Varex Imag­ing as a key com­po­nent for one of the most pop­u­lar X-ray in­dus­trial lin­ear ac­cel­er­a­tor sys­tems, com­monly used for se­cu­rity and NDT ap­pli­ca­tions. Being sig­nif­i­cantly strained by ex­ces­sive back­stream­ing, in­creas­ing of the ABC out­put is a chal­leng­ing task. We de­scribe these chal­lenges and high­light high power test re­sults. The tri­ode gun and struc­ture de­sign im­prove­ments al­lowed us to raise sta­ble out­put up to 530 Rad/min/1m at 3 MeV and up to 220 Rad/min/1m at 4.5 MeV with a widely avail­able 2.5-MW/2.7-kW mag­netron, while main­tain­ing the spot size at 2 mm.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA41  
About • Received ※ 03 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 20 September 2022
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WEPA53 An Open Radiofrequency Accelerating Structure coupling, GUI, impedance, SRF 753
 
  • S.V. Kuzikov
    Euclid TechLabs, Solon, Ohio, USA
  
  We re­port an open multi-cell ac­cel­er­at­ing struc­ture. Being in­te­grated with a set of open-end wave­guides, this struc­ture can sup­press high-or­der modes (HOMs). All the ac­cel­er­at­ing cells are con­nected at the side to rec­tan­gu­lar cross-sec­tion wave­guides which strongly cou­pled with free space or ab­sorbers. Due to the anti-phased con­tri­bu­tion of the cell pairs, the op­er­at­ing mode does not leak out, and has as high-qual­ity fac­tor as for a closed ac­cel­er­at­ing struc­ture. How­ever, the com­pen­sa­tion does not occur for spu­ri­ous high-or­der modes. This op­er­at­ing prin­ci­ple also al­lows for strong cou­pling be­tween the cells of the struc­ture, which is why high ho­mo­gene­ity of the ac­cel­er­at­ing fields can be pro­vided along the struc­ture. We dis­cuss the ob­tained sim­u­la­tion re­sults and pos­si­ble ap­pli­ca­tions. Its in­clude a nor­mal con­duct­ing high-shunt im­ped­ance ac­cel­er­a­tor, a tun­able pho­toin­jec­tor’s RF gun, and a high-cur­rent, high-se­lec­tive SRF ac­cel­er­a­tors.  
poster icon Poster WEPA53 [1.817 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA53  
About • Received ※ 01 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 12 August 2022 — Issue date ※ 16 August 2022
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FRXD6 Bunch Length Measurements at the CEBAF Injector at 130 kV laser, electron, simulation, cavity 917
 
  • S. Pokharel, G.A. Krafft
    ODU, Norfolk, Virginia, USA
  • M.W. Bruker, J.M. Grames, A.S. Hofler, R. Kazimi, G.A. Krafft, S. Zhang
    JLab, Newport News, Virginia, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
In this work, we in­ves­ti­gated the evo­lu­tion in bunch length of beams through the CEBAF in­jec­tor for low to high charge per bunch. Using the Gen­eral Par­ti­cle Tracer (GPT), we have sim­u­lated the beams through the beam­line of the CEBAF in­jec­tor and an­a­lyzed the beam to get the bunch lengths at the lo­ca­tion of chop­per. We per­formed these sim­u­la­tions with the ex­ist­ing in­jec­tor using a 130 kV gun volt­age. Fi­nally, we de­scribe mea­sure­ments to val­i­date these sim­u­la­tions. The mea­sure­ments have been done using chop­per scan­ning tech­nique for two in­jec­tor laser drive fre­quency modes: one with 500 MHz, and an­other with 250 MHz. 		 
slides icon Slides FRXD6 [0.800 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-FRXD6  
About • Received ※ 02 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 10 August 2022 — Issue date ※ 01 September 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)