Evaluation method of critical current and current sharing temperature for large-current Cable-in-Conduit conductors

Nunoya, Yoshihiko; Isono, Takaaki; Sugimoto, Makoto; Takahashi, Yoshikazu; Nishijima, Gen*; Matsui, Kunihiro; Koizumi, Norikiyo; Ando, Toshinari*; Okuno, Kiyoshi

Analysis of critical current () and current sharing temperature () was performed to the ITER Center Solenoid (ITER-CS) Model Coil Insert. Voltage behavior related to normal state transition of the conductor during or measurement has not been well understood especially in case of such a large cable with more than one thousand strands as this coil. From the detailed analysis of the voltage behavior of the coil, it is found that the average of electric field in the strand-longitudinal direction over the conductor cross section is equal to the average field of one strand along the conductor length, whose integral was measured by the voltage taps during the coil test. It is because twist pitch of the cable is less than the range of longitudinal field variation in this case. This evaluation method can estimate voltage behavior and predict and values, which are important parameters for the design of a large conductor coil, based on the property of strands composing the conductor.