Current Sharing Temperature of the ITER-TF Insert

The Central Solenoid (CS) model coil program was established in 1992 as one of projects in the Engineering Design Activities (EDA) of the International Thermonuclear Experimental Reacter (ITER). Current sharing temperature (Tcs) measurement of an ITER toroidal field insert (TF insert) was performed. The coil is a Nb3Sn superconducting coil, and was installed inside of the ITER CS model coil as a backup field coil. The relation between the voltage of an individual strand composed of the TF insert conductor and the measured voltage using the taps on the jacket were investigated, and evaluation method for Tcs measurement was established. The obtained results show that there was a discrepancy between the expected value from the strand data and the measured value, which is lower by about 1.2K. Some discrepancy was observed just after cooling down the insert before energizing.