Wideband Vertical Intra-Bunch Feedback at the SPS - Technology Development, Recent Accelerator Measurements and Next Steps

A wideband vertical intra-bunch feedback system is in development at the CERN SPS for use to control potential Ecloud and TMCI instabilities. The work is motivated by planned intensity increases from the LIU and HL-LHC upgrade programs. System technical features include pickups, upgraded kickers and related RF power amplifiers, 1 GHz bandwidth analog processing used in conjunction with a 4 GS/sec reconfigurable digital signal processing system. Recent results include driven beam experiments and beam simulation methods to verify the damping provided by the wideband system, and validate reduced MIMO models and model-based controllers. Noise effects and uncertainties in the model are evaluated via SPS measurements to predict the limits of control techniques applied to stabilize the intrabunch dynamics. We present data showing the excitation and damping of unstable modes. The plans for the next year, including experimental measurements, hardware upgrades and future control developments are described. INTRODUCTION CONTROL OF INTRA-BUNCH INSTABILITIES Pickup Kicker Front End Equalizer Back End Equalizer ADC Amplifier Controlled Delay DAC Fir