Localization of transverse impedance sources in the SPS using headtail macroparticle simulations

In particle accelerators, the beam coupling impedance is one of the main contributors to instability phenomena that lead to particle losses and beam quality deterioration. For this reason these machines are continuously monitored and the global and local amount of impedance needs to be evaluated. In this work we present our studies on the local transverse impedance detection algorithm. The main assumptions behind the algorithm are described in order to understand limits in reconstructing the impedance location. The phase advance response matrix is analyzed in particular for the nominal gamma transition SPS lattice (Q26), studying the different response from 90, 180, 270 degree phase advance sections. The thin lenses scheme is also implemented and new analytical formulas for phase advance beating were derived. This enabled us to put reconstructing lenses everywhere in the lattice, and to study their positioning scheme. Limits in linear response are analyzed. This relates the upper and lower limits in reconstruction to the phase advance measurement accuracy and the linear response regime limit. Copyright © 2011 by IPAC'11/EPS-AG.