Abstract Body

AC loss reduction is achieved by using multifilament structure. Copper-plating is effective to improve stability against local defect or local normal transition. However, it deteriorates the effect of the as loss reduction. To reconcile both features, we wound copper-plated multifilament coated conductor spiral geometry on the round core to decay the shielding current quickly and decouple each filament. We call such conductor SCSC cable (Spiral Copper-plated Striated Coated-conductor cable). SCSC cable can reduce the coupling losses because the loop of coupling current is small. However, the temperature dependence of coupling time constants is not clear. The transverse resistance is affected by the resistivity of the copper layer and various interface resistances. Since SCSC cable are expected to be used at various temperatures, it is useful to clarify its temperature dependence.

We measured the magnetization losses of spiral copper-plated multifilament coated conductors with various copper thickness at various temperatures between 4.2 K and 77 K. The amplitude of the applied magnetic field was 0.15 mT so that coupling losses dominate compared to hysteresis losses. Set frequencies up to 20 kHz to observe frequency dependance of magnetization. We separated observed magnetization losses into hysteresis losses and coupling losses then obtain coupling time constants. We also measure the resistivity of copper layer to assess transverse resistance using 4-probe method at various temperature. We discuss the relation between copper resistivity and coupling time constants and evaluated the temperature dependence of coupling time constants.

Acknowledgment

This work was supported by JST-Mirai Program Grant Number JPMJMI19E1, Japan.