Current distributions at steady-state of superconducting cable conductors for AC use

In order to obtain information towards achieving uniformity of current dist ribution in superconducting cable conductors for AC use, we develop a compa ct measuring system that enables us to quantitatively evaluate the current distribution. In this system current distribution is found from the observe d results of the self-field measured by a group of coils, each of which is composed of six small pick-up coils, located around the sample conductor. I t is confirmed that the accuracy and the sensitivity of this system are goo d enough to measure the current distributions for the superconducting cable conductors for AC use by adopting it to a dummy conductor composed of insu lated copper wires. Using this system, we experimentally investigate how th e localized transport current, in the steady, not quenched state, is made u niform in the superconducting cable conductor composed of strands without i nsulation for AC use. By this experiment, we can observe how the localized current transfers among the non-insulated strands. At the same time, the fr equency dependence of the change of the current distribution can be observe d as well. These measured results are discussed using approximate analysis relating to the inter-strand coupling effect.