Spear3 Booster Rf System Upgrade: Performance Requirements and Evaluation of Resources*

The SPEAR2 accelerator system originally had 3 RF stations (2 for storage ring, 1 Booster) operating at 358.5 MHz. SPEAR3 now operates at 476.3 MHz with the PEPII type RF system, while the Booster RF frequency remains unchanged. For top-off operation, the Booster injects single 3.0 GeV electron bunches into SPEAR3 at 10 Hz every 5 minutes to replenish lost charge. Due to the frequency mismatch between SPEAR3 and the Booster, only one SPEAR3 bucket can injected per shot limiting injection rate and overall system flexibility. The aging high-power RF subsystems of the Booster pose a reliability issue as well. In order to remove these constraints, studies are underway to replace the Booster RF system using the PEP-II type RF system as a baseline. The new Booster RF system will be tuned to 475.036 MHz, and phase-locked to the SPEAR3 RF system. The project calls for ramping the Booster cavity gap voltage to 0.80 MV at 10 Hz, each with a 40 ms acceleration interval. With very low beam loading and low average RF power, there are many subsystems that can be operationally simplified. In this paper we present the results of analysis leading to a new Booster RF system.