CERN Accelerating science

Article
Title	Present Status and Upgrade of BPM System in KEK Photon Factory
Author(s)	Obina, T ; Cheng, W X ; Haga, K ; Honda, T ; Tadano, M
Affiliation	(KEK, Ibaraki)
Publication	2005
In:	7th European Workshop on Beam Diagnostics and Instrumentation for Particle Accelerators, Lyons, France, 6 - 8 Jun 2005, pp.196
Subject category	Accelerators and Storage Rings
Abstract	In the KEK-PF, we improve the beam-position monitors (BPMs) and orbit correction system as a part of straight-sections upgrade project. Two different types of BPMs have been used until now, namely the 6-electrode type and the 4-electrode type. We replace the old 6-electrode one by the 4-electrode one, and increase the total number of BPMs from 65 to 77. The additionally installed BPMs are mainly used for local feedback for insertion devices. During the users operation, we only use the fast global orbit feedback which consists of DSP and fast-corrector magnets that can be used up to 100Hz. Because the number of the fast-corrector magnets is limited to 28, drifts of the beam orbit are remained in some location. We plan to install new magnets and build slow orbit correction system controlled by the workstation. The algorithm for the synchronous operation of fast and slow feedback is carefully designed to avoid the conflicts between two feedback loops. Developments of the fast local feedback system are also in progress. We are evaluating the FPGA-based system that can handle the feedback cycle faster than 1 kHz. The operation will start from Sep/2005.