A cable-in-conduit (CIC) conductor using an Nb3Sn strand is applied to the ITER TF coil. The performance of CIC conductor was degraded due to electromagnetic force. This is because a strand in the conductor is subjected to periodically bending strain by electromagnetic force, which causes the performance to become degraded. Strands in the conductor touch each other in a complicated manner due to twisting and the electromagnetic force is transferred via another strand, which leads to complication of bending strain distribution in the conductor. The complicated bending strain distribution makes it difficult to simulate the conductor performance analytically. The author thus developed a new model to evaluate conductor performance using a periodically bent strand model developed in a past study. However, the calculated result showed some error when compared to actual measured results. This may be due to the difference of physical phenomenon between a single freely bent strand and a strand constricted by an adjacent strand in the conductor. The author thus redeveloped a calculation model taking this effect into account. As a result, conductor performance can be successfully simulated. This indicates that a more practical solution can be achieved in quantitative evaluation of conductor performance.
