Development of a digital longitudinal damper for the TLS storage ring

A digital longitudinal damper is being developed in SRRC to stabilize the longitudinal coupled-bunch instabilities observed in the TLS storage ring. It is a bunch by bunch feedback system designed for 200 bunches at 2 ns bunch interval. Designs of the bunch phase detection circuit, the digital electronics and the 1125 MHz wideband RF system for correction of phase errors are presented in this article. The core of the digital electronics is a DSP array that utilizes commercially available DSP modules performing parallel processing at a data throughput of 500 Mbytes/sec. This will greatly reduce the time required for both hardware and software developments. A prototype operating at one eighth of the data rate of the final system is under construction to evaluate the system design