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Kim, Y.

Paper Title Page
MOPAS037 New Generation Digital Longitudinal Feedback System for Duke FEL and HIGS Facilities 518
 
  • Y. Kim, M. D. Busch, P. Wang, W. Wu, Y. K. Wu
    FEL/Duke University, Durham, North Carolina
  • J. Choi, I. S. Ko, I. S. Park
    PAL, Pohang, Kyungbuk
  • D. Teytelman
    Dimtel, Redwood City, California
 
  To increase intensity of the High Intensity Gamma-ray Source (HIGS) which is driven by the Duke storage ring FEL via Compton scattering, stored beam current should be increased. However, high-current multi-bunch operation in the Duke storage ring is limited by strong longitudinal coupled-bunch beam instabilities. To control those instabilities, we have been developing an active longitudinal feedback system which is based on the Integrated Gigasample Processor (iGP) through collaboration with Dimtel, Inc. and Pohang Accelerator Laboratory. In this paper, we report the present status of our longitudinal feedback system.  
TUPMS014 Commissioning of the Booster Injector Synchrotron for the HIGS Facility at Duke University 1209
 
  • S. F. Mikhailov, M. D. Busch, M. Emamian, S. M. Hartman, Y. Kim, J. Li, V. Popov, G. Swift, P. W. Wallace, P. Wang, Y. K. Wu
    FEL/Duke University, Durham, North Carolina
  • O. Anchugov, N. Gavrilov, G. Y. Kurkin, Yu. Matveev, D. Shvedov, N. Vinokurov
    BINP SB RAS, Novosibirsk
  • C. R. Howell
    TUNL, Durham, North Carolina
 
  Funding: This work is supported by the US DoE grant #DE-FG02-01ER41175

A booster synchrotron has been built and recently commissioned at Duke University Free Electron Laser Laboratory (DFELL) as part of the High Intensity Gamma-ray Source (HIGS) facility upgrade. HIGS is developed collaboratively by the DFELL and Triangular Universities Nuclear Laboratory (TUNL). The booster will provide top-off injection into the Duke FEL storage ring in the energy range of 0.27 - 1.2 GeV. When operating the Duke storage ring to produce high energy Compton gamma ray beams above 20 MeV, continuous electron beam loss occurs. The lost electrons will be replenished by the booster injector operating in the top-off mode. The compactness of the booster posed a challenge for its development and commissioning. The booster has been successfully commissioned in 2006. This paper reports experience of commissioning and initial operation of the booster.

 
FRPMS039 Growth Time of Longitudinal Coupled Bunch Mode Instability in the Duke FEL Facility 4036
 
  • Y. Kim, J. Li, Y. K. Wu
    FEL/Duke University, Durham, North Carolina
 
  To determine the required power of an RF amplifier for the longitudinal feedback system (LFS), the growth time of the longitudinal coupled bunch mode instability (CBMI) in the Duke storage ring should be known in advance. In 2005, we measured the longitudinal beam instability with four and eight symmetrically filled buckets in the Duke storage ring. By analyzing measured data, the growth time of the longitudinal CBMI can be estimated. At a beam energy of 274 MeV, the projected growth time is about 0.37 ms for a total stored current of 160 mA. To damp harmful longitudinal CBMI with a relative energy deviation of 0.1% (rms) within the growth time, a sufficient RF power of 135 W (rms) should be delivered to an LFS kicker at a central frequency of 758.8375 MHz. In this paper, we describe measurements of the growth time and the estimation of the RF power requirement for the LFS.