Quench analysis of an ITER 13T-40kA Nb3Sn coil (CS insert) Original Research Article

In order to analyze the quench characteristic of a cable-in-conduit (CIC) conductor that has a sub-cooling channel at the center of conductor cross section, an axisymmetric two-dimensional calculation model was developed. The tests and calculation results of the central solenoid (CS) insert were compared regarding the pressure drop and the behavior of the total voltage, temperature and normal zone propagation in the quench. They show good agreement. Therefore, the effectiveness of the calculation model is verified. It was also found that there is coolant convection between the central channel and bundle region even in a steady state. This makes the pressure drop in the central channel larger than that in a cylindrical pipe which has a smooth surface. In addition, it was found that the higher temperature of the coolant flowing through the central channel heats the coolant and the cable in the bundle region. It can be said that the hot coolant flowing through the central channel accelerates normal zone propagation.