First Results and Analysis of the Performance of a 4 GS/s Intra-Bunch Vertical Feedback System at the SPS

We present experimental measurements taken from SPS machine development studies with an intra-bunch feedback channel. These studies use a 3.2 GS/s digital signal processing system to implement general-purpose control algorithms on multiple samples across a single SPS bunch. These initial studies concentrate on single-bunch motion, and study the vertical betatron motion as the feedback control is varied. The studies are focused on validating simulation models of the beam dynamics with feedback. Time and frequency domain results include excitation and damping of intra-bunch motion with positive and negative feedback. We present initial results showing the impact of wideband feedback to excite/damp internal modes of vertical motion as well as stabilize an unstable beam.