Performance of Nb₃Sn-Cu In Situ Conductor in a Superconducting Magnet

Abstract

A small superconducting magnet was constructed from in situ prepared Nb₃Sn-Cu wire in order to test the suitability of this conductor material for use either as an insert magnet at 4.2K in the 10T range or as a stand alone magnet operating on a closed cycle refrigerator in the 10 to 14K range. The conductor was a single strand untwisted wire made by the Sn core process and stabilized with a jacket of pure Cu. Initial tests in a pool of liquid helium showed that the magnet critical current reached 90% of short sample performance with no evidence of training or changes in the field-current relation on repeated cycling even with repeated quenches. Subsequent tests on a close cycle refrigerator showed that the magnet was remarkably stable and gave a very reproducible magnetic field-current relation.