Estimation of performance of Nb3Sn CICC with thermal strain distribution

Abstract

Abstract In the last few years, the critical temperature (T c) of several ITER cable-in-conduit conductors (CICC) was determined by magnetization measurements at zero current. The distribution of the critical temperatures (T c), caused by variation of strain in the Nb3Sn strands, was found to vary with the number of load cycles. A comparison with mechanical modelling requires the strain distribution, while the T c distribution is sufficient to determine the CICC performance. The current sharing temperature (T cs) is calculated supposing that the measured distribution of T c is representative of its variation along a single strand and that the current is uniformly distributed among the strands. The T cs values, found for background and peak magnetic field, are compared with the results of the DC test in the SULTAN facility. The presented estimation techniques lead to an overestimation of T cs. The differences of the estimated and measured T cs values are discussed including the effect of different current-voltage characteristics of single strands and CIC conductors.