Development of a 10-meter wedged-pole undulator

Abstract A permanent magnet hybrid undulator of 10-m length is under construction at Spectra Technology, Inc. for use in free electron laser experiments at the Boeing Aerospace Company. The undulator system includes a remotely-adjustable compound taper as needed to explore simultaneous achievement of high extraction and high optical gain in the 1 μm wavelength range. Notable improvements relative to the earlier tapered hybrid undulator (THUNDER) include the use of wedged poles for higher field strength and a magnetically seamless structure which accommodates frequent two-plane steering correction without drift spaces. An important development is the finding that magnetic field errors can be substantially reduced using thin iron shims attached to the permanent magnets.