Publications by Douglas Bett

An FPGA-based turn-by-turn beam position monitoring system for studying multiple bunch beams in the ATF damping ring

DIPAC 2011 - Proceedings of the 10th European Workshop on Beam Diagnostics and Instrumentation for Particle Accelerators (2011) 230-232

GB Christian, RJ Apsimon, DR Bett, PN Burrows, B Constance, MR Davis, A Gerbershagen, C Perry, J Resta Lopez

Instabilities associated with beam-size blow-up have previously been observed with multi-bunch beam in the damping ring (DR) of the KEK Accelerator Test Facility (ATF). A system has been developed to monitor such instabilities, utilising an ATF stripline beam position monitor (BPM) in the DR, and BPM processor hardware designed for the FONT upstream feedback system in the ATF extraction line. The system is designed to record the horizontal and/or vertical positions of up to three bunches in the DR in single-bunch multi-train mode or the head bunch of up to three trains in multi-bunch mode, with a bunch spacing of 5.6 ns. The FPGA firmware and data acquisition software were modified to record turn-by-turn data for up to six channels and 1-3 bunches in the DR. The maximum memory configuration on the FPGA allows 131071 bunch-turn-channels of data to be recorded from a particular machine pulse, and the system has the capability to select only certain turns at a regular interval in which to record data, in order to zoom out and cover the entire period of the damping cycle at the ATF. An overview of the system and initial results will be presented.

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