Fast digital dampers for the Fermilab Booster

As the intensity levels of the Fermilab Booster are pushed higher, it becomes necessary to have greater control over beam instabilities. One way to control these instabilities is with bunch-by-bunch active beam damping. This kind of damping imposes a very tight tolerance for the electrical delay from the detector to the deflector. The electrical delay must match the bunch revolution time, and the revolution time changes by 685 ns in a period of 25 ms in the booster. One way to track this delay is with a fast, time varying digital delay which is synchronized with the RF feedback system. A working prototype of a wide-band transverse digital damper system has been developed and tested on the Fermilab Booster. This paper discusses the design, features, and results of the damper as well as problems associated with designing dampers for fast frequency sweeping accelerators.