| Paper |
Title |
Page |
| THPLS111 |
Beam Loading Measurement and its Application to the Harmonic RF Control of the APS PAR
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3538 |
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- C. Yao, E.E. Cherbak, N.P. Di Monte, A. Grelick, T. Smith, B.X. Yang
ANL, Argonne, Illinois
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The particle accumulator ring (PAR) has dual rf systems: a CW mode fundamental rf system (RF1) operating at 9.77 MHz that accumulates multiple linac pulses into a 0.8-ns bunch, and a 12th harmonic rf (RF12) that compresses the bunch length further to 0.34 ns for injection into the booster. The RF12 capture process is critical for optimal performance of the PAR. We investigated the effects of beam loading during the RF12 capture and bunch length compression process with both spectrum analysis and streak camera imaging. Based on these observations, a new timing scheme for the RF12 tuner and power control was implemented, which has substantially improved the performance of the PAR. We report our observation, the new timing scheme, and beam parameters after optimization.
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| THPLS112 |
Electron Multipacting Observation and Simulation in the APS PAR
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3541 |
| |
- C. Yao, Y.-C. Chae
ANL, Argonne, Illinois
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The particle accumulator ring (PAR) has both fundamental and 12th harmonic rf systems. Gap voltage fluctuations were experienced after vacuum work was performed on the PAR during a maintenance period. This has caused intermittent beam instability and prevented us from running the PAR fundamental rf system at normal power level. Our investigation has concluded that the problem was caused by electron multipacting in the center vacuum chamber of the cavity. We were able to suppress the multipacting by applying a solenoid field in the suspected region. Computer simulation is underway in order to find the location and the parameter range of the multipacting. In this paper we report the experimental observations and results of the simulation relevant to the phenomena.
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