Commissioning of the feedback systems at the VEPP-4M collider

During the high-energy physics experiments carried out at the VEPP-4M electron-positron collider, one of the major problems decreasing the operation efficiency is the longitudinal multi-bunch instability. The instability occurs due to the bunch-to-bunch interaction via long-living wake-fields induced in the accelerating RF cavities. To suppress this instability, a longitudinal bunch-by-bunch feedback system has been developed. For future operation of VEPP-4M at higher energy the beam current should be considerably increased. The principal beam current limitation is the transverse mode coupling instability, for suppression of which a broadband bunch-by-bunch digital feedback system is developed. For both feedback systems, the design, performance and first commissioning results are described