Comparison of filter designs for a digital beam-phase feedback system in a Heavy-Ion Synchrotron

The bunched particle beam in a synchrotron can perform various longitudinal oscillation modes of which the dipole mode occurs most frequently. Although naturally damped by Landau damping, these oscillations can become unstable if driven accordingly. In any case Landau damping is accompanied by filamentation of the bunch which leads to rms emittance blow up and thus reduces the beam quality. Therefore a beam-phase feedback is used to damp dipole oscillations. At GSI Helmholtzzentrum fur Schwerionenforschung GmbH the feedback is designed as an FIR filter [1]. However, the feedback performance may be improved using a matched filter instead of the current filter setting as is demonstrated in this work by comparing the different filter designs.