Development of a 10-m wedged-pole undulator

A 10-m rare-earth permanent magnet hybrid undulator called NISUS (Near-Infrared Scalable Undulator System) is being installed for use in the Boeing Aerospace Company (BAC) fee-electron laser (FEL) program series. The design has been optimized for operation at a 1- mu m wavelength with the BAC accelerator parameters. A remotely adjustable compound taper is utilized to achieve optimum startup gain and high-saturated extraction. Notable improvements include the use of wedged poles for higher field strength and a magnetically seamless structure which accommodates frequency 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. It is concluded that NISUS has achieved the goals of scalability, modularity, serviceability, and high field quality needed for advanced FEL and synchrotron radiation application.<>