Digital transverse bunch-by-bunch feedback system of Hefei light source

The design and primary experiment of the digital transverse bunch-by-bunch feedback system in Hefei light source are introduced. This transverse feedback system was developed to conquer the transverse coupled-bunch instabilities. It employed direct sampling front-end to simplify the electric circuits and tuning work. Because of the close tunes of horizontal and vertical directions. The FPGA code of the digital feedback processor was reprogramed to fulfill two-independent-feedback in one-processor. Through the beam test, the digital feedback system could suppress the transverse instabilities, and increase the injection beam current.