Analytical study of degradation of CIC conductor performance due to strand bending and buckling

Kajitani, Hideki; Hemmi, Tsutomu; Murakami, Haruyuki; Koizumi, Norikiyo

Critical current of cable-in-conduit conductors (CICCs) for ITER TF coils was measured. It was found from these test results that the measured critical current was lower than that evaluated from the critical current performance of a single strand. One of the explanations for this phenomenon is a non-uniform current distribution due to (1) unbalanced resistance among strands and between the strand and the upper/bottom joint and (2) local degradation of strand in the conductor. It is reported that the former was improved by using solder-filled joint but the latter issue seems to still remain. Therefore, the author developed a new analysis model for the calculation of strain distribution in the conductor taking account of strand bending and buckling and then, combined this with the electrical circuit model developed by authors before. Simulation results show that when local degradation is significant, the conductor performance can be degraded. In this presentation, these results are reported.