Measurement of current distribution in multi-strand superconducting cables for AC use in both steady and transient states

We experimentally investigate current distribution in steady and transient states in multi-strand superconducting cables composed of strands without insulation for AC use. The current distributions are indirectly measured from the results of the self-field distribution observed by a group of pickup coils located around the cable. Several patterns of localized current distribution induced by heaters are measured using two different types of pickup coils. The current values are calculated from the measured voltage values of pickup coils. The obtained results from these calculations show that the transient changes of the current distributions can be successfully measured and explained. Further, we observe that the localized current distribution tends to be uniform with increasing frequency. On the basis of the obtained results characteristics of current distributions in the AC superconducting cable are discussed.