Evaluation of the current sharing temperature of the ITER Toroidal Field Model Coil

The construction and testing of the Toroidal Field Model Coil (TFMC) is part of one of the ITER large R&D projects. The main goal was to demonstrate the feasibility and the mechanical integrity of the design. One of the highlights of the first test phase was to measure the current sharing temperature, T_CS, of the conductor by heating the helium entering from the inlet. Because neither temperature sensors nor voltage taps are positioned inside the coil, only the helium inlet temperature and the voltage along the whole conductor length can be used for the evaluation of T_CS. In addition, an inner pancake joint is located at the inlet in a rather high magnetic field and the peak field region is only about 1.5 m apart from the joint. The determination of the T_CS relies on the exact knowledge of the thermohydraulics of both the joint and the conductor region. The paper describes and compares the different numerical models used for the evaluation of the T_CS. Nine T_CS tests at different coil currents were performed, all ending in a quench. The measured T_CS is in good agreement with the expectations.