Performance tests of a fast electromagnetic phase shifter for a polarization-controlled undulator

A 27-m polarization-controlled undulator that consists of four horizontal and four vertical undulator segments and seven phase shifters will be installed and used at SPring-8 as the most highly brilliant soft x-ray source for the material science beamline of the University of Tokyo. We designed and fabricated a phase shifter prototype to satisfy requirements for the phase shifter. The phase shifter prototype consists of three H-type dipole magnets and the yokes are made of 0.1-mm thick permalloy laminations united and insulated by varnish. The phase shifter prototype showed good performance in reproducibility and frequency response. Furthermore, the integrated AC magnetic field of the prototype was measured with a long coil system and could be easily suppressed to below 1 G·cm by adjusting the coil currents. Now we are developing a flip coil system to measure the integrated DC magnetic field quickly and accurately. (author)