Assembly Procedures for a Nb3Sn Undulator Demonstration Magnet

An Nb3Sn planar undulator demonstration magnet is under development at the NHMFL. Key technological aspects include a 15 mm period, a target of 0.8 T on the beam and a beam tube that is thermally isolated from the windings. Two yoke assembly procedures are explored. First, a modular approach in which each racetrack is wound, reacted and impregnated separately before assembly with iron pole pieces and the creation of joints between the racetracks. The second approach is based on the more traditional single-piece yoke on which the conductor is wound on a fully iron yoke, followed by heat treatment and impregnation of the entire assembly. Each approach is used to build a 10-racetrack coil; both coils are tested at 4.2 K in liquid helium. Results of the coil tests are discussed, as well as joint development and testing, leading to a choice of assembly method for the demonstration magnet.