Properties of fiber-reinforced niobium-tin superconductor fabricated by bronze process

We are developing a fiber reinforced type of superconductor for large scale, high-field magnets. Formerly we used the sputtering process to develop a niobium-tin conductor reinforced with a tungsten fiber and showed that this type of conductor has excellent stress tolerance. For practical applications however, a conventional fabrication process like bronze process is desirable. Hence we have tried to fabricate a fiber-reinforced type niobium-tin conductor utilizing tantalum fiber as the reinforcing member, In this conductor, each niobium-tin filament has a tantalum core of about 20-/spl mu/m diameter, We adopted tantalum as the core material since it has both good ductility and mechanical strength comparable to stainless steel, This conductor showed a reasonable critical field of about 22 T and good mechanical strength compared to a niobium-tin conductor fabricated by the conventional bronze process.