Analysis of current distribution in joint of conductor sample for ITER Central Solenoid (CS)

Hase, Takashi*; Shimizu, Tatsuya; Hemmi, Tsutomu; Matsui, Kunihiro; Koizumi, Norikiyo; Takahashi, Yoshikazu; Okuno, Kiyoshi

NbSn conductors (40 kA, 13 T) are employed in ITER CS. The characteristics of the sample in which two kinds of conductors are connected with OFC blocks will be evaluated. The joint part will be exposed to fields widely ranging from 0.29-8.4 T when an external field of 11 T is generated. Therefore, current distribution due to the magnetic resistance may bring incorrect evaluation of performance of the sample. The current distribution in the joint part of the conductor has been analyzed with the FEM to confirm the speculation and to get an idea for make the current distribution more uniformly. It has been found as a result that the current distribution in the conventional joint structure employing the OFC with a RRR of 100 leads to a current density ratio of 1.65, though a total resistance is very low. On the contrary, by employing copper plate of RRR = 4, the current density ratio can be reduced to 1.23, while keeping the total resistance below 2 n.