High field superconductor development and understanding: A. Establishing the limits of performance of niobium-titanium; B. Establishing whether Chevrel phase materials could become useful high field superconductors

Rapid progress in the development of high current density conductor in the period 1982--1992. At the beginning of this period the best strand for the FermiLab Tevatron was attaining 2000a/mm2 at 5T (4.2K), with variable product quality; by 1991 commercial strand was obtainable at over 3000A/mm2 in very long piece lengths. The most important contribution to this advance was the understanding of the role of the Nb-Ti microstructure in the determination of the intrinsic current carrying capacity of the strand. A complete wire fabrication facility was created at the UW making it possible to control all aspects of strand production. These facilities further accelerated our understanding of the extrinsic processing limitations to the Jc of the conductors. Results on Chevrel phase materials (PbMo8) showed that HIP-ed samples had complete connectivity; there is no intrinsic granularity to Chevrel phases. Flux pinning was studied in SnNo6S8