Author: Whiteford, C.
Paper Title Page
MOPAB287 The Development of Single Pulse High Dynamic Range BPM Signal Detector Design at AWA 909
 
  • E.M. Siebert, S. Baturin
    Northern Illinois University, DeKalb, Illinois, USA
  • D.S. Doran, G. Ha, W. Liu, P. Piot, J.G. Power, J.H. Shao, C. Whiteford, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
 
  Funding: the US Department of Energy, Office of Science
Sin­gle pulse high dy­namic range BPM sig­nal de­tec­tor has been on the most wanted list of Ar­gonne Wake­field Ac­cel­er­a­tor (AWA) Test Fa­cil­ity for many years. Unique ca­pa­bil­i­ties of AWA beam­line re­quire BPM in­stru­men­ta­tion with an un­prece­dented dy­namic range, thus cost ef­fec­tive so­lu­tion could be chal­leng­ing to de­sign and pro­to­type. Our most re­cent de­sign, and the re­sults of our quest for a so­lu­tion, are shared in this paper.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB287  
About • paper received ※ 19 May 2021       paper accepted ※ 23 June 2021       issue date ※ 13 August 2021  
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MOPAB352 High Power Test of a Dielectric Disk Loaded Accelerator for a Two Beam Wakefield Accelerator 1096
 
  • B.T. Freemire, C.-J. Jing, S. Poddar
    Euclid Beamlabs, Bolingbrook, USA
  • M.E. Conde, D.S. Doran, G. Ha, W. Liu, J.G. Power, J.H. Shao, C. Whiteford, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
  • M.M. Peng
    TUB, Beijing, People’s Republic of China
  • E.E. Wisniewski
    Illinois Institute of Technology, Chicago, Illinois, USA
  • Y. Zhao
    Euclid TechLabs, Solon, Ohio, USA
 
  Funding: Small Business Innovation Research Contract No. DE-SC0019864 U.S. DOE Office of Science Contract No. DE-AC02-06CH11357
As part of the Ar­gonne 500 MeV short pulse Two Beam Wake­field Ac­cel­er­a­tion Demon­stra­tor, a sin­gle cell X-band di­elec­tric disk loaded ac­cel­er­a­tor (DDA) has been de­signed, fab­ri­cated, and tested at high power at the Ar­gonne Wake­field Ac­cel­er­a­tor. The DDA should pro­vide a short pulse (~20 ns) high gra­di­ent (>300 MV/m) ac­cel­er­a­tor while main­tain­ing a rea­son­able r/Q and high group ve­loc­ity. This will allow a sig­nif­i­cantly larger RF-to-beam ef­fi­ciency than is cur­rently pos­si­ble for con­ven­tional ac­cel­er­at­ing struc­tures. A low loss bar­ium ti­tan­tate ce­ramic, µr = 50, was se­lected, and a low tem­per­a­ture braz­ing alloy cho­sen to pre­serve the di­elec­tric prop­er­ties of the ce­ramic dur­ing braz­ing. High power test­ing pro­duced break­down at the triple junc­tion, re­sult­ing from the braze joint de­sign. No ev­i­dence of break­down was ob­served on the iris of the disk, in­di­cat­ing that the max­i­mum sur­face elec­tric field on the di­elec­tric was not reached. An im­proved braze joint has been de­signed and is in pro­duc­tion, with high power test­ing to fol­low.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB352  
About • paper received ※ 19 May 2021       paper accepted ※ 08 June 2021       issue date ※ 21 August 2021  
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TUXB06
High Transformer Ratio Plasma Wakefield Acceleration and Current Profile Reconstruction Using Emittance Exchange  
 
  • R.J. Roussel
    Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
  • G. Andonian, A. Deng, C.E. Hansel, G.E. Lawler, W.J. Lynn, R. Robles, J.B. Rosenzweig, K. Sanwalka
    UCLA, Los Angeles, USA
  • S. Baturin
    Northern Illinois University, DeKalb, Illinois, USA
  • M.E. Conde, D.S. Doran, G. Ha, J.G. Power, J. Seok, C. Whiteford, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
 
  Funding: This work is supported by the Department of Energy, Office of High Energy Physics, under Contract No. DESC0017648.
To over­come lim­its on total ac­cel­er­a­tion achiev­able in plasma wake­field ac­cel­er­a­tors, spe­cially shaped drive beams can be used to in­crease the trans­former ratio, im­ply­ing that the drive beam de­cel­er­a­tion is min­i­mized in com­par­i­son with ac­cel­er­a­tion ob­tained in the wake. We re­port the re­sults of a non­lin­ear PWFA, high trans­former ratio ex­per­i­ment using high-charge, lon­gi­tu­di­nally asym­met­ric drive beams in a plasma cell. An emit­tance ex­change process is used to gen­er­ate vari­able drive cur­rent pro­files, in con­junc­tion with a long (mul­ti­ple plasma wave­length) wit­ness beam. The wit­ness beam is en­ergy-mod­u­lated by the wake­field, yield­ing a re­sponse that con­tains de­tailed spec­tral in­for­ma­tion in a sin­gle-shot mea­sure­ment. Using these meth­ods, we gen­er­ate a va­ri­ety of beam pro­files and char­ac­ter­ize the wake­fields, di­rectly ob­serv­ing beam-loaded trans­former ra­tios up to 7.8. Fur­ther, a spec­trally-based cur­rent re­con­struc­tion tech­nique, val­i­dated by 3D par­ti­cle-in-cell sim­u­la­tions, is in­tro­duced to ob­tain the drive beam pro­file from the de­cel­er­at­ing wake­field data.
 
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TUPAB295 Upgrade to the EPICS Control System at the Argonne Wakefield Accelerator Test Facility 2173
 
  • W. Liu, J.M. Byrd, D.S. Doran, G. Ha, A.N. Johnson, P. Piot, J.G. Power, J.H. Shao, G. Shen, C. Whiteford, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
 
  Funding: US Department of Energy, Office of Science
The Ar­gonne Wake­field Ac­cel­er­a­tor (AWA) Test Fa­cil­ity has used a com­pletely home­brewed, MS Win­dows-based con­trol sys­tem for the last 20 years. In an ef­fort to mod­ern­ize the con­trol sys­tem and pre­pare for an ac­tive ma­chine learn­ing pro­gram, the AWA will work with the Ad­vanced Pho­ton Source (APS) con­trols group to up­grade its con­trol sys­tem to EPICS. The EPICS con­trol sys­tem is ex­pected to fa­cil­i­tate col­lab­o­ra­tions and sup­port the fu­ture growth of AWA. An overview of the pre­vi­ous AWA con­trol and data ac­qui­si­tion sys­tem is pre­sented, along with a vi­sion and path for com­plet­ing the EPICS up­grade.
 
poster icon Poster TUPAB295 [1.108 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB295  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 30 August 2021  
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TUPAB296 LLRF Upgrade at the Argonne Wakefield Accelerator Test Facility 2176
 
  • W. Liu, D.S. Doran, G. Ha, P. Piot, J.G. Power, J.H. Shao, C. Whiteford, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
  • L.R. Doolittle, D. Filippetto, D. Li, S. Paiagua, C. Serrano, V.K. Vytla
    LBNL, Berkeley, California, USA
 
  Funding: US Department of Energy, Office of Science
The Ar­gonne Wake­filed Ac­cel­er­a­tor (AWA) Test Fa­cil­ity de­signed and op­er­ated a home­made LLRF sys­tem for the last 20 years. It is based on NI-PXI prod­ucts that has now be­come ob­so­lete. The AWA’s LLRF can­not keep up with the in­creas­ing sta­bil­ity de­mands of AWA’s up­graded fa­cil­ity. An over­haul of the sys­tem is strongly de­sired. With the sup­port from DOE-HEP, the AWA is col­lab­o­rat­ing with Lawrence Berke­ley Na­tional Lab­o­ra­tory (LBNL)to up­grade its LLRF sys­tem with mod­ern in­stru­men­ta­tion to meet the grow­ing sta­bil­ity de­mands. An overview of AWA’s cur­rent LLRF sys­tem per­for­mance is pre­sented to­gether with the up­grade plan and ex­pec­ta­tions.
 
poster icon Poster TUPAB296 [1.943 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB296  
About • paper received ※ 19 May 2021       paper accepted ※ 05 July 2021       issue date ※ 26 August 2021  
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THPAB331 High-Power Test of a Highly Over-Coupled X-Band RF Gun Driven by Short RF Pulses 4432
 
  • J.H. Shao, D.S. Doran, W. Liu, J.G. Power, C. Whiteford, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
  • C.-J. Jing, S.V. Kuzikov
    Euclid TechLabs, Solon, Ohio, USA
  • X. Lu, P. Piot, W.H. Tan
    Northern Illinois University, DeKalb, Illinois, USA
 
  Beam bright­ness, a key fig­ure of merit of RF pho­to­cath­ode guns, can be im­proved by in­creas­ing the cath­ode sur­face field which sup­presses emit­tance growth from space charge. The sur­face field in nor­mal-con­duct­ing struc­tures is mainly lim­ited by RF break­down and it has been ex­per­i­men­tally dis­cov­ered that RF break­down rate ex­po­nen­tially de­pends on RF pulse length. A highly over-cou­pled 1.5-cell X-band pho­to­cath­ode gun has been de­vel­oped to be pow­ered by 9 ns RF pulses with 3 ns ris­ing time, 3 ns flat-top, and 3 ns falling time gen­er­ated by an X-band metal­lic power ex­trac­tor. In the re­cent ex­per­i­ment at Ar­gonne Wake­field Ac­cel­er­a­tor fa­cil­ity, cath­ode sur­face field up to ~350 MV/m with a low break­down rate has been ob­tained under ~250 MW input power. Strong beam load­ing from dark cur­rent was ob­served dur­ing RF con­di­tion­ing and quickly re­cov­ered to a neg­li­gi­ble level after the gun reached the max­i­mum gra­di­ent. De­tailed high-power test re­sults and data analy­sis will be re­ported in this man­u­script.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB331  
About • paper received ※ 25 May 2021       paper accepted ※ 14 July 2021       issue date ※ 23 August 2021  
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