CORC Cables: Numerical Characterization of the Critical Current after Bending

Abstract

To satisfy requirements of high operating current densities, compact layouts, and the possibility to reach magnetic field higher than 20T, at temperatures from 4.2K to 20K, e.g., necessary for the development of next generation of colliders, the CORC® cable concept is of particular interest. Based on ReBCO high temperature superconducting tapes wound around a copper former, it exploits round cross-section guaranteeing electrical and mechanical isotropy. However, these cables can degrade as a result of the winding process and operating conditions, as ReBCO tapes are strain-sensitive. This paper presents a 3D multi-physics numerical model for characterizing the critical current (Ic) of bended ReBCO CORC® cables, based on a T-A formulation implemented in COMSOL Multiphysics® coupled with a thermal model of a straight cable, already validated against experimental results. The tape is approximated as a thin shell, taking advantage of its high aspect ratio, and the Ic scaling for the tape accounts for the local strain. A pure geometrical strain evaluation on the tape surface allow to properly account for the punctual degradation of Ic, as an input for the multi-physics model. The assessment of the voltage-current curve for the bent conductor has been compared to experimental results.