BUNCH-BY-BUNCH FEEDBACK FOR THE PHOTON FACTORY STORAGE RING

The Photon Factory (PF) ring will start the top-up operation or the continuous injection in 2006. Previously the octupole magnets were used to suppress the transverse coupled bunch instability and RF modulation method to enhance the bunch length has been effectively used to suppress the longitudinal instabilities. However, such kind of methods are not suitable for the top-up operation, we are preparing active bunch-by-bunch feedback systems for both transverse and longitudinal planes. The transverse feedback system has been installed along with the straight-sections upgrade, this system uses a FPGA based feedback processor board developed at the SPring-8, both horizontal and vertical signals are processed in a single control loop. For the longitudinal feedback, a twoport DAFNE type wide-band cavity has been designed and is now manufacturing, a digital signal processing part is under design. The system will start commissioning in autumn 2006.