High field superconductor development and understanding: A. Establishing the limits of performance of niobium titanium; B. Establishing whether Chevrel Phase materials can become useful high field superconductors. Progress report, June 1, 1992--May 31, 19

摘要

The acquisition of a hydrostatic extrusion press now allows us to extrude composites under controlled conditions and enables us to fabricate new composite designs. We have successfully extruded a variety of composites including powder metallurgy APCs. Our conventional APC composite has been successfully brought to the completion of its fabrication. The results of the characterization of that composite have proven to be quite exciting. There is proof that the ''ideal'' microstructures that are hoped for in APC composites can be made. The flux pinning force of our APC composite is stronger than that for a conventional composite, despite having about half of the volume fraction of pins and a lower B(sub c2) than occurs in a conventional composite. Additionally, the uniform nature of the microstructure makes our APC composite well-suited for more fundamental studies of flux pinning. We have fabricated thin film ''model'' conductors in order to understand basic flux-pinning mechanisms and these films have yielded interesting data on the importance of film geometry. Further advances have been made in increasing the J(sub c) of Chevrel Phase conductors and a clear path is now outlined for further improvement.