Simulation of Transient Effects of Beam-Transverse Feedback Interaction with Application to the Extraction of the CNGS Beam from the SPS

For existing and future high energy proton accelerators, transverse feedback systems play an essential role in supplying the physics experiments with high intensity beams at low emittances. We developed a simulation model to study the interaction between beam and transverse feedback system in detail, bunch-by-bunch and turn-by-turn, considering the technical implementation at the SPS [1]. A numerical model is used as the non linear behaviour (saturation) and limited bandwidth of the feedback system, as well as the transient nature at injection and extraction, complicates the analysis. The model is applied to the practical case of the CNGS beam [2] in the SPS accelerator. This beam will be ejected from the SPS in two batches causing residual oscillations by kicker ripples on the second batch. This second batch continues to circulate for 50 ms (about 2170 turns) after the first batch has been extracted and oscillations are planned to be damped by the feedback system.