Author: Jing, C.-J.
Paper Title Page
TUPME058 The Argonne Wakefield Accelerator (AWA): Commissioning and Operation 1503
 
  • M.E. Conde, S.P. Antipov, D.S. Doran, W. Gai, C.-J. Jing, C. Li, W. Liu, J.G. Power, J.Q. Qiu, J.H. Shao, C. Whiteford, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • S.P. Antipov, C.-J. Jing, J.Q. Qiu
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • S. Cao
    IMP, Lanzhou, People's Republic of China
  • C. Li, J.H. Shao
    TUB, Beijing, People's Republic of China
  • E.E. Wisniewski
    Illinois Institute of Technology, Chicago, Illinois, USA
 
  Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
The commissioning of the upgraded AWA facility is well underway. The new L-band electron gun has been fully commissioned and has been successfully operated with its Cesium Telluride photocathode at a gradient of 80 MV/m. Single bunches of up to 100 nC, and bunch trains of four bunches with up to 80 nC per bunch have been generated. The six new accelerating cavities (L-band, seven cells, pi mode) have been RF conditioned to 12 MW or more; their operation at 10 MW brings the beam energy up to 75 MeV. Measurements of the beam parameters are presently underway, and the use of this intense beam to drive high gradient wakefields will soon follow. One of the main goals of the facility is to generate RF pulses with GW power levels, corresponding to accelerating gradients of hundreds of MV/m and energy gains on the order of 100 MeV per structure.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME058  
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TUPME059 Longitudinal Bunch Shaping with a Double Dogleg based Emittance Exchange Beam Line 1506
 
  • G. Ha, M.E. Conde, W. Gai, C.-J. Jing, K.-J. Kim, J.G. Power, A. Zholents
    ANL, Argonne, Illinois, USA
  • M.-H. Cho, G. Ha, W. Namkung
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
 
  Funding: Work supported by High Energy Physics, Office of Science, US DOE.
A new program is under development at Argonne National Laboratory (ANL) to use an emittance exchange (EEX) beamline to produce longitudinally shaped electron bunches. While the ultimate goal is to generate triangular shapes for high transformer ratio wakefield acceleration we are also exploring, in general, the capability of the double dogleg EEX beamline to control the bunch shape. We are studying effects that degrade the quality of the longitudinal current profile including: non-uniform particle distribution, emittance, the deflecting cavity thick-lens effect, 2nd order effects, space charge effects and coherent synchrotron radiation effects. We will present the double dogleg EEX beamline layout and the diagnostic design as well as give a progress report on the experimental status of the program.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME059  
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TUPME040 Drive Beam Break-up Control and Practical Gradient Limitation in Collinear Dielectric Wakefield Accelerators 1443
 
  • C. Li, W. Gai, J.G. Power, A. Zholents
    ANL, Argonne, Ilinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • C. Li, C.-X. Tang
    TUB, Beijing, People's Republic of China
 
  Dielectric wakefield accelerator (DWA) concept has gained significant attention for the need of the future large scale facilities. For a practical machine, one needs to overcome a major challenge for the DWA that is the efficient energy extraction and stable propagation at the same time for the drive beam. Typically, a slightly off axis beam become unstable in the dielectric channel due to transverse wakefield excitation, that could be controlled if a strong external alternating magnetic focusing channel applied at the same time. However, there is limitation on the practical magnetic field in the focusing channel (typically < 1 Tesla), thus imposing operating point for the DWA. In this article, we explore the operating point of the DWA for various structure frequencies and drive beam charge, particularly on the gradient and total acceleration distance, and provide guidance on the DWA design.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPME040  
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WEPRO008 A Beam-driven Microwave Undulator for FEL 1956
 
  • A. Kanareykin, C.-J. Jing, P. Schoessow
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • S. Baturin
    LETI, Saint-Petersburg, Russia
  • A. Zholents
    ANL, Argonne, Ilinois, USA
 
  Funding: DOE SBIR
Microwave waveguides can in principle be used for undulators with periods less than 1 cm. Intensive work has been done on the recently proposed design that operates at the HE11 hybrid mode of a corrugated waveguide; successful experimental results have been reported recently [S.Tantawi Talk at POSIPOL 2012]. In this presentation we propose a beam driven design for an undulator based on an electron bunch train powering a microwave or mm waveguide. The drive bunch train propagates towards the undulating beam inside a dielectric loaded structure or corrugated waveguide generating high power RF. The “smart” waveguide design and a proper bunch spacing of the electron drive beam train provide single mode generation of the high magnitude undulating field that gives an undulator parameter in the range of K~1 for a high frequency device.*
*A. Zholents, HBEB Workshop, Puerto-Rico, 2013.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO008  
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WEPRO118 THz Radiation Generation in Multimode Wakefield Structures 2248
 
  • S.P. Antipov, S.V. Baryshev, C.-J. Jing, A. Kanareykin, P. Schoessow
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • M.G. Fedurin
    BNL, Upton, Long Island, New York, USA
  • W. Gai, A. Zholents
    ANL, Argonne, Ilinois, USA
  • D. Wang
    TUB, Beijing, People's Republic of China
 
  Funding: DOE SBIR
A number of methods for producing sub-picosecond electron bunches have been demonstrated in recent years. A train of these bunches is capable of generating THz radiation via multiple mechanisms like transition, Cherenkov and undulator radiation. We propose to use a bunch train like this to selectively excite a high order mode in a dielectric wakefield structure. This allows us to use wakefield structures that are geometrically larger and easier to fabricate for beam-based THz generation. In this paper we present a THz source design based on this concept and experimental progress to date.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO118  
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THPRI076 Laser Triggered RF Breakdown Study Using an S-band Photocathode Gun 3943
 
  • J.H. Shao, W. Gai
    ANL, Argonne, Illinois, USA
  • H.B. Chen, Y.-C. Du, W.-H. Huang, J. Shi, C.-X. Tang, L.X. Yan
    TUB, Beijing, People's Republic of China
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • F.Y. Wang
    SLAC, Menlo Park, California, USA
 
  A laser triggered RF breakdown experiment was carried out with an S-band photocathode gun at Tsinghua University for attempting understanding of the RF breakdown processes. By systematic measurement of the time dependence of the breakdown current at the gun exit and the stored RF energy in the cavity, one might gain insight into the time evolution of RF breakdown physics. A correlation of the stored energy and field emission current has been analysed with an equivalent circuit model. Experimental details and analysis methods are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI076  
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THPRI077 Electric Field Enhancement Study using an L-band Photocathode Gun 3946
 
  • J.H. Shao, W. Gai
    ANL, Argonne, Illinois, USA
  • H.B. Chen, J. Shi
    TUB, Beijing, People's Republic of China
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • F.Y. Wang, L. Xiao
    SLAC, Menlo Park, California, USA
 
  RF breakdown in high gradient accelerating structures is a fundamental problem that is still needed better understanding. Past studies have indicated that field emission, which is usually represented by electric field enhancement (i.e. β) produced from the Fowler-Nordheim plot, is strongly coupled to the breakdown problem. A controlled surface study using a high gradient L-band RF gun is being carried out. With a flat cathode, the maximum electric field on the surface reached 103 MV/m. And electric field as high as 565 MV/m on the surface was achieved by a pin-shaped cathode. The field enhancement factor was measured at different surface field during the conditioning process. Initial results of the study are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI077  
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