Performance of in situ superconductors in solenoids

A series of small solenoids have been wound from in situ prepared Nb3-Sn-Cu superconducting wire in order to determine the suitability of these materials for magnets which require bending strains greater than 2% at the surface of the wire. In the range from 4 to 14 T, J/sub c/ of the solenoid is equivalent to or exceeds performance for unstrained material. For best performance in ac fields, it is essential to twist the wire and to support the windings with a potting material. Calorimetric measurements of the ac losses in the 8--12 T range give 1 mW/cm3 for magnetic fields ramped at 1 T/s