Overview of Nb3Sn and V3Ga conductor development in Japan

In the early stage of high-field A15 conductor development in Japan, different type of V3Ga conductors were fabricated. Then, Ti-doped Nb3Sn conductors have been developed, and widely used for high-field generation. Increase of Sn concentration in the bronze produces an appreciable progress in the performance of bronze processed (Nb,Ti)3Sn conductors. New internal Sn processed (Nb,Ti)3Sn conductors with modified cross-sectional configurations have been produced, which exhibit large Jc in high fields as well as reduced AC loss. Both bronze processed and internal Sn processed (Nb,Ti)3Sn conductors satisfy recent ITER magnet specifications. As for new type Nb3Sn conductors, powder core and Jelly Roll processed (Nb,Ta)3Sn wires with improved high-field performance have been fabricated.