Analysis of the current distribution in the ITER CS-insert model coil conductor by self field measurements

Non-uniformities in the paths of the currents in a cable-in-conduit conductor (CICC), resistive or inductive, will result into an unbalanced current distribution. The current nonuniformity may affect the performance of a magnet system and it is therefore essential to evaluate this phenomenon. The current distribution in the Central Solenoid Insert Coil (CSIC) from the Central Solenoid Model Coil (CSMC) experiment is reconstructed from the four Hall-sensor voltages at the top and bottom joint of the CSIC. Four Hall sensors are used, near both joints at the extremities of the cable, to measure the self-field of the conductor. The inverse identification problem is solved in order to find the currents that match as close as possible to the set of measured data. Solutions are found for the current amplitudes in the six petals of the cable from the set of measurements of the tangential field component. Differences in the petal currents are found which rate up to a factor of two.