Tooling Design, Coil Fabrication, and Prototype Coil Performance Verification for a 28 GHz Nb3Sn ECR Ion Source Magnet

Worldwide several superconducting electron cyclotron resonance (ECR) ion sources have been developed and in operation for heavy ion accelerators using Nb-Ti magnets. To explore the use of high-field Nb3Sn to break the field limit of Nb-Ti for ECR magnets, state-of-the-art Nb3Sn coil fabrication techniques and tooling design must be used to address the challenging characteristics of Nb3Sn conductors. Earlier we reported the overall magnet design, conductor selection, and conductor characterization for building a 28 GHz superconducting ECR ion source using Nb3Sn sextupole coils for Facility for Rare Isotope Beams (FRIB). This paper describes the progress towards fabricating prototype Nb3Sn sextupole coil. In particular, we present tooling design, Nb3Sn sextupole coil fabrication, and a mirror magnet for performance verification.