INVESTIGATION OF THE R56 OF A PERMANENT MAGNET PHASE SHIFTER

In the European XFEL permanent magnet phase shifters will be used routinely between two undulator segments. Their main purpose is to control the ponderomotive phase of the electrons with respect to the emitted radiation. In addition the path length is dependent on the electron energy, which corresponds to a small R56. In this paper we investigate the R56 of a permanent magnet phase shifter and propose to use it to fine tune R56 by adjusting the phase shifter gap.