Abstract Body

Superconductor cables consisting of coated conductors wound spirally on metal core in multiple layers, such as the CORC^® cable, are attracting interests because of their large current carrying capacities. Another advantage of such cables is current sharing among coated conductors improving robustness against local defects in coated conductors: the current can bypass the local defect in a coated conductor through others, and, then, the fatal blockage of current in the coated conductor can be prevented. Such bypassing currents are speculated, but their experimental observations were quite limited, and, the reported ones were not clear. Furthermore, even if there were not defect in all coated conductors composing a cable, the current distribution among coated conductors could be far from uniform because of imbalanced connecting resistances at terminals of the cable and/or imbalanced inductances among coated conductors. In such backgrounds, the current distribution measurements in such cables are very important to clarify their current transport characteristics.

In this study, we introduce two measurement methods of a two-layer spiral coated conductors. A sample used in experiments is shown schematically in Fig. 1. Each layer consists of two coated conductors wound spirally on a metal core. The first measurement method is by using the Hall sensors. The difference between the winding directions as well as the winding pitches of the two layers are utilized: the two layers generate different longitudinal magnetic fields along the core of the cable. The generated longitudinal magnetic field can be measured by the Hall sensors installed in the hallow core, then the currents in the two layers can be calculated. The second method is by using the pick-up coil wound around the cable, which can also measure the longitudinal magnetic field. We will compare the two method and discuss their advantages and their disadvantages.

This work was supported by JST-ALCA-Next Program Grant Number JPMJAN24G1, Japan.