Author: Huang, X.
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TUPGW099 Superconducting Crab Cavity Options for Short X-Ray Pulse Generation in SPEAR3 1647
  • F. Toufexis, V.A. Dolgashev, X. Huang, Z. Li
    SLAC, Menlo Park, California, USA
  Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
We are exploring methods to generate short X-ray pulses in SPEAR3 on the order of 1 ps to enable studying ultrafast processes in materials. We are developing a 2-frequency crab cavity scheme with two sets of crab cavities* at the 6th and 6.5th harmonics of the 476 MHz ring RF frequency. In previous work we studied a normal conducting crab cavity for SPEAR3**. In this work we explored two superconducting cavity options: a traditional elliptical cavity and the Quasi-waveguide Resonator***. We found that the Quasi-waveguide Resonator cannot meet our field uniformity specifications due to higher order multipole fields. We then optimized a traditional elliptical cavity with the input, Lower Order Modes, and Higher Order Modes couplers following the Argonne Advanced Photon Source design.
* A. Zholents, et al, Nucl. Instrum. Methods Phys. Res., Sect. A, Vol. 425 (1999), p. 385.
** Z. Li, et al, Proceedings of IPAC17.
*** A. Lunin, et al, Proceedings of HOMSC14.
DOI • reference for this paper ※  
About • paper received ※ 11 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB112 Commission of the Transverse Bunch-by-Bunch Feedback at SPEAR3 4081
  • K. Tian, W.J. Corbett, X. Huang, N. Kurita, D.J. Martin, J.A. Safranek, J.J. Sebek
    SLAC, Menlo Park, California, USA
  • D. Teytelman
    Dimtel, San Jose, USA
  Funding: Work supported by US Department of Energy Contract DE-AC03-76SF00515.
Driven by the demand of suppressing transverse beam instabilities and developing novel short pulse operation modes in SPEAR3 storage ring, a wide-band transverse bunch-by-bunch feedback system has been recently commissioned for SPEAR3 storage ring. The system was demonstrated to be sufficient to suppress the transverse coupled bunch instabilities caused by trapped RF modes in one of the in vacuum insertion devices. A new function of beam instability interlock has been developed and is part of machine protection system for the in vacuum insertion device. In addition, the bunch-by-bunch feedback system serves as a indispensable diagnostic tool that enables us to measure machine parameters, beam impedance, and characteristics of the beam instability modes. In this paper, we describe the scheme and performance of the bunch-by-bunch feedback system at SPEAR3.
DOI • reference for this paper ※  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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