Wideband Vertical Intra-Bunch Feedback At The SPS - 2015 Results And Path Forward

We present experimental measurements taken from CERN SPS machine development studies with a wideband intra-bunch feedback channel prototype. The demonstration system is a digital processing system with recently installed wideband kicker and amplifier components. This new hardware extends the bandwidth up to 1GHz and allows driving and controlling multiple vertical transverse modes in the bunch. The studies are focused on both driving the bunch with spectrally controlled signals to identify a reduced model of the bunch dynamics and testing model-based feedback controllers to stabilize the bunch dynamics. The measurements are structured to validate reduced MIMO models and macro-particle simulation codes, including the dynamics and limits of the feedback channel. Noise effects and uncertainties in the model are evaluated via SPS measurements to quantify the limits of control techniques applied to stabilize the intrabunch dynamics. The design of controllers for Q26 and Q20 optics are illustrated and future control developments are described.