Temperature and current margin of ITER central solenoid conductor designs during a 15 MA plasma scenario

The plasma current of the international thermonuclear experimental reactor (ITER) will be induced by current pulses in the central solenoid (CS). The foreseen lifetime and operating conditions, with currents up to 45 kA at 13 T, pose significant mechanical challenges for the brittle Nb3Sn strands. On top of this, inter-strand coupling loss should remain restricted during pulsed operation to ensure an achievable repetition rate of plasma cycles. In order to address the degradation of Nb3Sn cable-in-conduit conductors (CICCs) with electromagnetic and thermal load cycling, four alternative cable designs have recently been tested in both DC and AC modes. However, the actual operating conditions experienced by the CS conductor within the ITER magnet system in terms of time-varying magnetic field and current cannot be fully reproduced in existing experimental facilities. In this paper, we present the results of the numerical assessment of the electromagnetic performance of the four ITER CS conductor designs during a 15 MA plasma scenario. The analysis was carried out with the code JackPot-ACDC including the voltage-current characteristic of all superconducting strands.