A characterization of internal-Sn Nb/sub 3/Sn superconductors for use in the proof of principles (POP) coil (for ITER)

High-performance, Ti-alloyed, internal-Sn superconductors have been selected for use in the Proof of Principles (POP) coil, a 1.0-m o.d., 0.4-m i.d. solenoid designed to produce fields up to 15 T. The POP coil will use forced-flow cable-in-conduit conductors (CICC) and will operate at 4.2 K and moderate levels of conductor strain. A report is presented on the results of detailed characterizations of two proposed POP coil Nb/sub 3/Sn 19 subelement superconducting wires of differing topology. An investigation has been conducted of the critical current as a function of applied field and applied strain. The wires were found to have excellent high-field properties, providing a high performance margin for the proposed POP coil. The field and strain dependence of J/sub c/ have been found to compare favorably with predictions from a wire performance model recently developed for Nb/sub 3/Sn superconductors.