Analysis of AC Losses in the ITER Central Solenoid Insert Coil

The circle-in-square cable-in-conduit conductor that will be adopted for the 3L module of the ITER Central Solenoid (CS) coil has been recently tested to assess its performance in conditions relevant for the real operation of the magnet. The tests on a ∼43-m-long conductor were performed in the CS Insert Project carried out under the responsibility of the US ITER Domestic Agency, in charge of the CS modules manufacturing. In this paper, we present an evaluation of the ac losses of this conductor aiming at the assessment of the nτ value for the conductor coupling losses. The electromagnetic (EM) and thermal-hydraulic (TH) analysis of these experiments is then performed. A detailed distribution of the coupling losses in the conductor is computed, with the electromagnetic part of the THELMA model. The obtained power density distribution is then input to the TH model (the 4C code) to compute the TH parameters (e.g., the temperature evolution at selected locations along the conductor) during Central Solenoid Model Coil current dumps. The EM/TH model is then validated against experimental data and used to extract relevant information on the conductor ac losses.