Development of a Nb3Sn multifilamentary composite conductor for a.c. use

A Nb3Sn composite conductor with approx. 10 000 submicron diameter filaments has been manufactured using the external diffusion process. A.c. losses were greatly reduced by the use of a fine filament size (0.53 μm, design value), a tight twist pitch (0.87 mm) and a small wire diameter (0.153 mm) with a bronze matrix. A triplex conductor was constructed by cabling three strands at a twisting pitch of 3 mm, and a small coil was wound from this cable. Preliminary studies have shown that, if this conductor is used in superconducting armature windings of rotating machines, economical benefits are obtained compared with the use of conventional armatures. (author)