Author: Jing, C.-J.
Paper Title Page
TUA2IO02
 DWFA Staging Results at the Argonne Wakefield Accelerator Facility (AWA)  
 
  • M.E. Conde, S.P. Antipov, D.S. Doran, W. Gai, Q. Gao, G. Ha, C.-J. Jing, W. Liu, N.R. Neveu, J.G. Power, J.Q. Qiu, C. Whiteford, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • S.P. Antipov, C.-J. Jing, J.Q. Qiu
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • Q. Gao
    TUB, Beijing, People's Republic of China
  • G. Ha
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
  
  Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
We report on recent Two-Beam-Acceleration (TBA) experiments conducted at the Argonne Wakefield Accelerator Facility (AWA), which used 70 MeV electron bunches to accelerate a 0.5 nC witness bunch in gradients of up to 150 MV/m. The wakefields were generated by the passage of the 15 - 45 nC drive bunches through iris-loaded metallic structures operating at 11.7 GHz. No indication of witness beam quality degradation was observed, and bunch charge was preserved during the acceleration process. Another series of experiments was conducted using two TBA stages, demonstrating acceleration of the witness beam in these two subsequent stages by means of two independent drive bunch trains. 		 
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WEPOB19 Summary of Cs2te Photocathode Performance and Improvements in the High-Gradient, High-Charge AWA Drive Gun 934
 
  • E.E. Wisniewski, S.P. Antipov, M.E. Conde, D.S. Doran, W. Gai, C.-J. Jing, W. Liu, J.G. Power, J.Q. Qiu, C. Whiteford
    ANL, Argonne, Illinois, USA
  • S.P. Antipov, C.-J. Jing, J.Q. Qiu
    Euclid TechLabs, LLC, Solon, Ohio, USA
  
  Funding: Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.
The AWA L-band, high-charge photoinjector for the 70 MeV drive beamline has been operating for almost 3 years at the Argonne Wakefield Accelerator (AWA) facility. at Argonne National Laboratory (ANL). The gun operates at high-field (85 MV/m peak field on the cathode) and has a high quantum efficiency (QE) Cesium telluride photocathode with a large area (30 mm diameter). It produces high-charge, short pulse, single bunches (Q > 100 nC) as well as long bunch-trains (Q > 600 nC) for wakefield experiments (high peak current). During the first two years of operation, photocathode performance was evaluated and areas of improvement were identified. After study, consideration and consultation, steps were taken to improve the performance of the photocathode. So far, in total, three photocathodes have been fabricated on-site, installed and operated in the gun. Improvements made to the photocathode plug, vacuum system, and gun operation are detailed. The results include vastly improved conditioning times, better cathode performance, and QE above 4% for over 11 months. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB19  
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WEPOB20 Multiple Scattering Effects on a Short Pulse Electron Beam Travelling Through Thin Beryllium Foils 937
 
  • E.E. Wisniewski, S.P. Antipov, M.E. Conde, D.S. Doran, W. Gai, Q. Gao, C.-J. Jing, W. Liu, J.G. Power, C. Whiteford
    ANL, Argonne, Illinois, USA
  • S.P. Antipov, C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • Q. Gao
    TUB, Beijing, People's Republic of China
  • G. Ha
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  
  Funding: Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.
The Argonne Wakefield Accelerator beamlines have stringent vacuum requirements (100 picotorr) necessitated by the Cesium telluride photoinjector. In direct conflict with this, the structures-based wakefield accelerator research program sometimes includes worthy but complex experimental installations with components or structures unable to meet the vacuum standards. A proposed chamber to sequester such experiments safely behind a thin beryllium (Be) window is described and the results of a study of beam-quality issues due to the multiple scattering of the beam through the window are presented and compared to GEANT4 simulations via G4beamline. Three thicknesses of Be foil were used: 30, 75 and 127 micron, probed by electron beams of three different energies: 25, 45, and 65 MeV. Multiple scattering effects were evaluated by comparing the measured transverse rms beam size for the scattered vs. unscattered beam. The experimental results are presented and compared to simulations. Results are discussed along with the implications and suggestions for the future sequestered vacuum chamber design. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB20  
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THPOA08 Transformer Ratio Enhancement Experiment Based on Emittance Exchanger in Argonne Wakefield Accelerator 1115
 
  • Q. Gao, H.B. Chen, J. Shi
    TUB, Beijing, People's Republic of China
  • S.P. Antipov
    Euclid Beamlabs LLC, Bolingbrook, USA
  • M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.G. Power, C. Whiteford, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  
  The transformer ratio is an important figure of merit in collinear wakefield acceleration, it indicates the efficiency of energy transferring from drive bunch to witness bunch. Higher transformer ratio will significantly reduce the length of accelerator thus reducing the cost of accelerator construction. However, for the gaussian bunch, this ratio has its limit of 2. To obtain higher transformer ratio, one possible method is to tailor the beam current profile to specific shapes. One method of beam shaping is based on emittance exchange, which has been demonstrated at the Argonne Wakefield Accelerator. Its principle is to tailor the beam transversely using a mask then exchange the beam's transverse profile and longitudinal profile. In this paper, we describe our efforts to optimize the beamline and mask in order to generate a triangular beam with quadratic head, which has a transformer ratio of 6.4. We also present our design of a dielectric slab based accelerating structure to measure the transformer ratio. Finally, we discuss an experiment for this high transformer ratio at Argonne Wakefield Accelerator Laboratory.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA08  
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