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Description
A Spiral Copper-plated Striated Coated-conductor (SCSC) cable is a round cable composed of striated REBCO coated-conductors (CCs) wrapped around a metal core wire. A REBCO film in each CC is divided into multifilaments by laser-striation, while Cu-plating surrounds the whole cross-section. Thanks to this structure, SCSC cables are promising for application to accelerator magnets since the impact of the screening current on the field quality can be reduced while keeping electrical and thermal robustness against local defects. A REBCO film in a CC is subjected to various stresses and strains during cabling, coil winding, resin impregnation of a coil, magnet assembly, cooling, and excitation. To ensure the reliable operation of a magnet, the electro-mechanical properties of SCSC cables must be understood.
As a first step, we evaluated the uniaxial tensile strain dependence of critical current (Ic) for REBCO CCs with a usual single filament or 10 filaments. In a striated CC, it has been reported that an electric field (E) – current (I) curve is strongly influenced by current-sharing among the filaments and the position of voltage taps. Indeed, we found that more complicated Ic-strain characteristics were observed in the striated CCs than in the CCs with a monofilament due to a change in E-I curved at the electric field level below or comparable to the Ic criterion. Controlling the position of voltage taps is essentially important for the striated CCs to determine a strain at which an irreversible degradation of Ic starts. Therefore, we tried to attach the voltage taps to a specific single filament. Then, the Ic-strain characteristics for the filaments at different locations in a width direction were evaluated. Based on these results, we will discuss the filament position dependence of the irreversible strain of Ic.
This work is supported in part by JST-ALCA-Next Program Grant Number JPMJAN24G1 and in part by Japan-U.S. Science and Technology Cooperation Program in High Energy Physics.
