Simulation of the ITER Poloidal Field Coil Insert DC performance with a new model

The Poloidal Field (PF) Coil Insert is made from a NbTi cable in conduit conductor and has been subjected to tests in the Central Solenoid Model Coil facility at JAEA in Japan. For the interpretation of the voltage tap signals from these tests, we adapted the JackPot model – which was used previously to analyse short sample tests – to simulate also the model coil experiments. A key ingredient of JackPot is that the local magnetic field on the superconducting strands and the inter-strand contact resistances all depend on the “trajectories” of the strands within the cable. These trajectories are precisely calculated, ensuring a realistic distribution of magnetic field- and contact resistance values. The results of the model calculations show that the applied joints are most likely responsible for the poor performance of short samples of similar PF conductors in earlier experimental tests. The model predicts that the influence of the joints is significantly less pronounced for the Poloidal Field Coil Insert.