Development of a Nb3Al conductor for toroidal field coils

Nb₃Al has potential capability in realizing a TF coil that can produce a magnetic field up to around 16 T because of the inherently high critical current at high field and less sensitivity against strains. Mass production technique of Nb₃Al strands was therefore established in 1990s and about 1 ton of strands were produced by the authors. Then, coil fabrication technique was developed and a large coil, the Nb₃Al insert, was fabricated. In addition, the prototype Nb₃Al conductor for JT-60 superconducting tokamak has already been developed. The test results of these coils demonstrate applicability of the Nb₃Al conductor to TF coil with react-and-wind method. The possibility of developing TF coils whose operating field is around 16 T seems to be promised through these successive results.