Beam position feedback systems for the PF storage ring

Two types of fast beam position feedback systems, global and local feedback systems, are proposed for a low-emittance configuration of the 2.5-GeV PF storage ring which will be started in 1997. The global feedback system corrects the closed orbit around the ring and the local feedback system stabilizes the beam positions and angles at insertion devices. Both systems are expected to suppress vibrations up to 50 Hz. For these systems, the beam position monitors will be improved to achieve fast data-taking and high position resolution, and the fast steering magnets and their power supplies will be reinforced. In the feedback control, VME bus-compatible DSP (digital signal processor) boards will be used for fast computation and a reflective memory network for fast data transfer. In a preliminary test, the global feedback DSP board was confirmed to have a computation performance enough for its purpose