Oxide superconducting wire, superconducting structure, method of producing oxide superconducting wire, superconducting cable, superconducting magnet, and product incorporating superconducting magnet

A method of producing an oxide superconducting wire, the method comprising the steps of:

• (a) filling a first metal sheath with a material powder including both a powder of an oxide superconductor and a powder of a nonsuperconductor;
• (b) processing the first metal sheath filled with the material powder by drawing to form a single-filament superconducting wire;
• (c) housing a plurality of single-filament superconducting wires described above into a second metal sheath;
• (d) processing the second metal sheath that houses the single-filament superconducting wires by drawing to form a multifilament superconducting wire;
• (e) processing the multifilament superconducting wire by rolling;
• and
• (f) heat-treating the rolled multifilament superconducting wire;
• in which method:
• (g) in the material powder, the number of particles in a powder of a nonsuperconductor having a particle diameter of at most 2 μm constitutes at least 95% of the total number of particles in the powder of the nonsuperconductor;
• (h) the cross-sectional areas of the single-filament superconducting wires in the multifilament superconducting wire before being processed by rolling have a coefficient of variation (COV) of at most 15%;
• (i) the step of processing the multifilament superconducting wire by rolling is performed at a rolling reduction of at most 82%;
• and
• (j) the step of heat-treating the rolled multifilament superconducting wire is performed under a pressure of at least 200 atmospheres.