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Grelick, A.

Paper Title Page
RPAE055 Results of Preliminary Tests of PAR Bunch Cleaning 3307
 
  • C. Yao, M. Borland, A. Grelick, A.H. Lumpkin, N. Sereno
    ANL, Argonne, Illinois
 
  Funding: This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

A particle accumulator ring (PAR) is used at the Advanced Photon Source (APS) to collect multiple linac bunches and compress them into a 0.3-ns (rms) single bunch for booster injection. A 9.77-MHz fundamental rf system and a 117.3-MHz harmonic rf system are employed for initial beam capture and bunch length compression. Satellite bunches with very low charge form due to rf phase drifts or beam loading change. These satellites, when injected into the booster and then into the storage ring (SR), cause bunch impurity at three buckets from the target bucket. Storage ring and booster bunch cleaning was tried but proved to be difficult due to the top-up mode of operation in the storage ring and tune drift in the booster synchrotron. Recently we implemented a PAR bunch-cleaning system with tune-modulated harmonic rf knockout. Preliminary tests gave a measured SR bunch purity of better than 10-6, which shows that the cleaning method is feasible and could achieve a bunch purity goal of 10-8. This report describes the system configuration, test results, and system performance.