ITER-CSインサート・コイルの臨界電流および分流開始温度

抄録

Critical current (I_C) and sharing temperature (T_CS) measurement of the ITER-CS insert coil were performed. The coil is Nb₃Sn superconducting coil and is installed inside the ITER-CS model coil. Voltage behavior related to normal state transition of a conductor during I_C or T_CS measurement has not been well understood, especially in such a large cable as this coil, which has more than 1, 000 strands, because the magnetic field, which makes much effect against superconduting property, is not constant inside of a cable. The authors analyzed voltage behavior of the conductor during the measurement and found that an averaging electric field gives reasonable clues to evaluate I_C or T_CS value, considering the twist pitch of the cables which is less than the range of the field variation in this case. The obtained result showed a lower T_CS value than the expected value from the strand by 0.2-0.4K.