Performance evaluation of the ITER Toroidal Field Model Coil phase I: Part 2: M&M analysis and interpretation

Abstract

The ITER Toroidal Field Model Coil (TFMC), a large (2.7 m × 3.8 m × 0.8 m) superconducting (Nb 3Sn) DC coil designed and constructed in collaboration between EU industries and laboratories coordinated by EFDA, has been tested during 2001 in the TOSKA cryogenic facility at Forschungszentrum Karlsruhe, Germany, achieving the nominal 80 kA at 7.8 T peak field and 86 MJ stored energy as a standalone coil (Phase I). The results of the current sharing temperature ( T CS) measurements at I=80, 69 and 57 kA, presented in a companion paper (Part 1), are evaluated here using the M&M code. The critical properties best fitting the experimental voltage-inlet temperature characteristic of the P1.2 pancake are deduced from the TFMC data under the assumption of an ideal collective behaviour of the strands. The TFMC results are compared first with the expected conductor performance, showing that at the maximal current the performance was borderline with what was expected, while at the minimal current tested it was better than expected. Second, they are compared with the performance of the single strand as measured in the lab, showing that, in order to reproduce the TFMC data, one has to invoke that some degradation, larger at higher current, occurred when going from the strand to the cable.