Advances in processing and characterizing Bi-based superconductors

Advances in the processing and fabrication of mono- and multifilament Bi-2223/2212 high-critical-temperature superconductors by the powder-in-tube technique continue to bring these materials closer to commercial applications. Consistently high critical- current densities (J_c) greater than 10⁴ A/cm₂ have been achieved along the entire length of a 1,260 m long, 37 filament Bi-2223 tape. Pancake-shaped coils, test magnets, and a prototype transformer were fabricated and characterized from such long conductors. Record high fields have been generated in prototype test magnets operated as inserts in the high background fields of conventional low-critical-temperature magnets. With an eye toward commercialization, this article reviews some of the recent advances in the processing and characterization of bismuth-based tapes.