Thermal-hydraulic analysis of Tcs measurement in conductor 1A of the ITER Central Solenoid Model Coil using the M&M code Original Research Article

We present a first study of current sharing temperature (Tcs) tests performed over the last few months in the Central Solenoid Model Coil (CSMC) experiment at JAERI, Naka, Japan. The CSMC is a superconducting magnet, layer-wound two-in-hand using 18 layers of Nb3Sn two-channel cable-in-conduit conductors, which very recently reached a record 13 T at 46 kA DC operation. Here we apply the multi-conductor Mithrandir (M&M) code to a selected set of shots with different transport currents (30, 40, and 46 kA) and we concentrate on conductor 1A on the innermost (i.e., with highest magnetic field) layer. In the test, resistive heaters located upstream of layers 1 and 2 are used to progressively and quasi-steadily increase the supercritical helium inlet temperature in the coil. The Tcs is reached when a threshold of 0.5 mV resistive voltage is measured across the coil, after which the heaters are turned off and the coil current is dumped. Computed results are compared with experimental data, showing good agreement in the inlet and outlet temperatures of all four heated conductors, both as Tcs is reached (30, 40 kA) and during the whole hour-long transient from nominal conditions to Tcs reached (46 kA).