Design, fabrication, and test results of undulators using Nb3Sn superconductor

An R&D effort is underway at Lawrence Berkeley National Laboratory (LBNL) to develop the technology of Nb3Sn superconducting undulators (SCUs). Issues relating to the selection of the appropriate conductor are discussed. The design and fabrication of SCUs using Nb3Sn is presented. Two prototype devices have been designed and fabricated at LBNL. The first device concentrated on basic fabrication issues and on magnet protection, a key concern due to extremely high copper current densities during a quench. Test on the first prototype demonstrated that such devices can be passively protected in a scalable manner. The second device incorporated design improvements as well as trim coils that are designed to serve as the basic element of a future active phase error correction approach. Preliminary tests on the second device are presented. The trim coils were successfully tested at a variety of field levels. Two quench runs were performed, both occurring at similar to 70% of short-sample J(c). Stability issues associated with flux-jumps and possible epoxy cracking are discussed.