Author: Bruker, M.W.
Paper Title Page
WEZD6 Manufacturing the Harmonic Kicker Cavity Prototype for the Electron-Ion Collider 601
 
  • S.A. Overstreet, M.W. Bruker, G.A. Grose, J. Guo, J. Henry, G.-T. Park, R.A. Rimmer, H. Wang, R.S. Williams
    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
High-bunch-fre­quency beam-sep­a­ra­tion schemes, such as the in­jec­tion scheme pro­posed for the Rapid Cy­cling Syn­chro­tron at the Elec­tron-Ion Col­lider, de­mand rise and fall times an order of mag­ni­tude below what can re­al­is­ti­cally be ac­com­plished with a stripline kicker. Nanosec­ond-time-scale kick wave­forms can in­stead be ob­tained by Fourier syn­the­sis in a har­mon­i­cally res­o­nant quar­ter-wave ra­dio-fre­quency cav­ity which is op­ti­mized for high shunt im­ped­ance. Orig­i­nally de­vel­oped for the Jef­fer­son Lab Elec­tron-Ion Col­lider (JLEIC) Cir­cu­la­tor Cooler Ring, a hy­po­thet­i­cal 11-pass ring dri­ven by an en­ergy-re­cov­ery linac at Jef­fer­son Lab, our high-power pro­to­type of such a har­monic kicker cav­ity, which op­er­ates at five modes at the same time, will demon­strate the vi­a­bil­ity of this con­cept with a beam test at Jef­fer­son Lab. As the geom­e­try of the cav­ity, tight me­chan­i­cal tol­er­ances, and num­ber of ports com­pli­cate the de­sign and man­u­fac­tur­ing process, spe­cial care must be given to the order of the man­u­fac­tur­ing steps. We pre­sent our ex­pe­ri­ences with the man­u­fac­tura­bil­ity of the pre­sent de­sign, lessons learned, and first RF test re­sults from the pro­to­type.
 
slides icon Slides WEZD6 [12.312 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEZD6  
About • Received ※ 04 August 2022 — Revised ※ 05 August 2022 — Accepted ※ 18 August 2022 — Issue date ※ 31 August 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPA12 Operational Experience of the New Booster Cryomodule at the Upgraded Injector Test Facility 640
 
  • M.W. Bruker, R. Bachimanchi, J.M. Grames, M.D. McCaughan, J. Musson, P.D. Owen, T.E. Plawski, M. Poelker, T. Powers, H. Wang, Y.W. Wang
    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.
Since the early 1990s, the in­jec­tor of the CEBAF ac­cel­er­a­tor at Jef­fer­son Lab has re­lied on a nor­mal-con­duct­ing RF graded-beta cap­ture sec­tion to boost the ki­netic en­ergy of the elec­tron beam from 100 / 130 keV to 600 keV for sub­se­quent ac­cel­er­a­tion using a cry­omod­ule hous­ing two su­per­con­duct­ing 5-cell cav­i­ties sim­i­lar to those used through­out the ac­cel­er­a­tor. To sim­plify the in­jec­tor de­sign and im­prove the beam qual­ity, the nor­mal-con­duct­ing RF cap­ture sec­tion and the cry­omod­ule will be re­placed with a new sin­gle booster cry­omod­ule em­ploy­ing a su­per­con­duct­ing, β = 0.6, 2-cell-cav­ity cap­ture sec­tion and a sin­gle, β = 0.97, 7-cell cav­ity. The Up­graded In­jec­tor Test Fa­cil­ity at Jef­fer­son Lab is cur­rently host­ing the new cry­omod­ule to eval­u­ate its per­for­mance with beam be­fore in­stal­la­tion at CEBAF. While demon­strat­ing sat­is­fac­tory per­for­mance of the booster and good agree­ment with sim­u­la­tions, our beam test re­sults also speak to lim­i­ta­tions of ac­cel­er­a­tor op­er­a­tions in a noisy, ther­mally un­reg­u­lated en­vi­ron­ment.
 
poster icon Poster WEPA12 [3.726 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA12  
About • Received ※ 03 August 2022 — Revised ※ 07 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 06 September 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPA13 New Results at JLab Describing Operating Lifetime of GaAs Photo-guns 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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WEPA24 pyJSPEC - A Python Module for IBS and Electron Cooling Simulation 672
 
  • H. Zhang, S.V. Benson, M.W. Bruker, Y. 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.
The in­tra­beam scat­ter­ing is an im­por­tant col­lec­tive ef­fect that can de­te­ri­o­rate the prop­erty of a high-in­ten­sity beam and elec­tron cool­ing is a method to mit­i­gate the IBS ef­fect. JSPEC (JLab Sim­u­la­tion Pack­age on Elec­tron Cool­ing) is an open-source C++ pro­gram de­vel­oped at Jef­fer­son Lab, which sim­u­lates the evo­lu­tion of the ion beam under the IBS and/or the elec­tron cool­ing ef­fect. The Python wrap­per of the C++ code, pyJSPEC, for Python 3.x en­vi­ron­ment has been re­cently de­vel­oped and re­leased. It al­lows the users to run JSPEC sim­u­la­tions in a Python en­vi­ron­ment. It also makes it pos­si­ble for JSPEC to col­lab­o­rate with other ac­cel­er­a­tor and beam mod­el­ing pro­grams as well as plen­ti­ful python tools in data vi­su­al­iza­tion, op­ti­miza­tion, ma­chine learn­ing, etc. In this paper, we will in­tro­duce the fea­tures of pyJSPEC and demon­strate how to use it with sam­ple codes and nu­mer­i­cal re­sults.
 
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA24  
About • Received ※ 02 August 2022 — Revised ※ 08 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 26 August 2022
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FRXD6 Bunch Length Measurements at the CEBAF Injector at 130 kV 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)