Demagnetization of undulator magnets irradiated high energy electrons

Abstract The magnetic field change of undulator magnets when exposed to a 2.0 GeV electron beam has been measured. We study the effect of (1) stacking magnets, of (2) magnet shape, of (3) magnetized direction, of (4) target materials, of (5) magnet materials, and of (6) manufacturers. Two undulator models adopting the actual magnet array dimensions of the in-vacuum undulators in SPring-8 were also irradiated.