Recent developments in processing HTS silver-clad Bi-2223 tapes, coils and test magnets

摘要

Considerable progress has been made in fabricating Bi-2223 high temperature superconductor (HTS) wires and tapes with high critical current densities that are attractive for electric power and high-field magnet applications. Powder-in-tube processed silver-clad Bi-2223 short tape samples, small coils and test magnets have been fabricated and measured at liquid nitrogen (77K), pumped liquid nitrogen (64 K), liquid neon (27K) and liquid helium (4.2K) temperatures. Optimization of thermo-mechanical process parameters have yielded J(sub c)'s in the superconducting core > 4.0 (times) 10(sup 4) A/cm(sup 2) at 77K zero field and > 2.0 (times) 10(sup 5) A/cm(sup 2) at 4.2K, zero field. Long lengths (up to 70 m) of mono-core conductors were fabricated and tested to carry significant amounts of current (23 A, (approximately)15,000 A/cm(sup 2)) at liquid nitrogen temperature. Recent test magnets assembled from pancake wound coils were measured to generate magnetic fields as high as 2.6, 1.8 and 0.36 Tesla at 4.2K, 27K and 77K respectively. These results show promise towards practical utilization of HTS materials.