High precision transverse bunch-by-bunch feedback system with FPGA and high resolution ADC

A bunch-by-bunch feedback system to damp betatron oscillations has been developed and in operation at SPring-8 storage ring since 2004. Each bunch is kicked by a force whose strength is determined from the transverse position measurement for the bunch to damp the beam oscillation in a short time. In the feedback system, Field Programmable Gate Array (FPGA) is employed resulting a fast signal processing and a low cost. In addition a high precision analog-to-digital converter (ADC) is introduced to suppress the effects of noises and to improve the accuracy of the bunch position measurement. It is expected that both of the horizontal and vertical oscillations are controlled by a single system owing to the fast action property of FPGA and a newly developed algorithm of the signal processing. (K.Y.)