Development of 46-kA Nb/sub 3/Sn conductor joint for ITER Model Coils

The conductor joint is one of the key technologies for superconducting coils. A butt type joint has been successfully developed for the ITER magnets. The 46 kA Nb/sub 3/Sn conductors are connected by the diffusion bonding technique in vacuum, after the reaction of Nb/sub 3/Sn. The advantage of this joint is low losses against pulse field, because the compacted part is very small compared with other types of joint. 15 butt joints have already been fabricated in the ITER CS Model Coil. According to the test results of the full-size conductor samples, these butt joints will be operated stably in the pulse operation, because the temperature increase due to ac losses and Joule heating by joint resistance is very small and the joint has a sufficiently high temperature margin.