Author: Seok, J.
Paper Title Page
MOPRB069 Generation of High Power Short Rf Pulses using an X-Band Metallic Power Extractor Driven by High Charge Multi-Bunch Train 734
 
  • J.H. Shao, M.E. Conde, D.S. Doran, G. Ha, W. Liu, J.G. Power, C. Whiteford, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • H.B. Chen, M.M. Peng, J. Shi, H. Zha
    TUB, Beijing, People’s Republic of China
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • J. Seok
    UNIST, Ulsan, Republic of Korea
 
  Short pulse two-beam acceleration (TBA) is a structure wakefield acceleration (SWFA) approach aiming to achieve gradient above 250 MV/m using rf pulses less than 20 ns. An X-band 11.7 GHz metallic power extractor has been developed as the power source to test accelerating structures in this extreme regime. The power extractor is designed to be driven by high charge bunches separated by 769.2 ps (9 times the X-band period) on an L-band 1.3 GHz beamline. In the recent experiment, ~280 MW rf pulses with 3 ns flat-top have been measured by a coaxial rf pickup when driven by 8-bunch trains with a total charge of ~500 nC. The power level is ~50% lower than the theoretical prediction and simulation. Experimental investigation suggests that the missing power was mainly caused by the multipacting issue inside the rf pickup, which could be eliminated by a newly-designed directional coupler.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB069  
About • paper received ※ 19 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPTS066 Suppression of Correlated Energy Spread Using Emittance Exchange 3275
 
  • J. Seok, M. Chung
    UNIST, Ulsan, Republic of Korea
  • M.E. Conde, G. Ha, J.G. Power
    ANL, Argonne, Illinois, USA
 
  An emittance exchange (EEX) provides a precise longitudinal phase space manipulation of electron bunch. It has been studied for an easy and precise control of temporal distribution, but controls of energy distribution have not been explored. Since the energy control using EEX is under the identical principle to the temporal control, the EEX beamline can control a correlated energy spread of the electron bunch. This would benefit accelerator facilities requiring a low energy spread such as X-ray Free Electron Laser Oscil-lator (XFELO). In this paper, we present principle and preliminary simulation work on the suppression of correlated energy spread using the EEX beamline. ing the EEX beamline.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS066  
About • paper received ※ 21 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPGW088 Transformer Ratio Measurements from Ramped Beams in the Plasma Blowout Regime using Emittance Exchange 3778
SUSPFO134   use link to see paper's listing under its alternate paper code  
 
  • R.J. Roussel, G. Andonian, W.J. Lynn, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • M.E. Conde, D.S. Doran, G. Ha, J.G. Power, C. Whiteford, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • J. Seok
    UNIST, Ulsan, Republic of Korea
 
  Funding: Work is supported by DOE contract DE-SC0017648.
We present initial measurements from a UCLA-Argonne Wakefield Accelerator collaborative plasma wakefield acceleration (PWFA) experiment aimed at demonstrating the dependence of transformer ratio on longitudinal beam shape. The transformer ratio or the ratio between the maximum acceleration of the witness and the maximum deceleration of the drive beam, is key to a mature, beam-based, plasma wakefield accelerator design. Utilizing the unique capabilities of the emittance exchange (EEX) beamline, we may obtain transformer ratios in excess of six in PWFA. We present the experimental beamline design, relevant beam diagnostics and explore preservation of the longitudinal beam profile.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW088  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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