Degradation analysis of REBCO coils

RE-Ba-Cu-O (REBCO) layer-wound coils were operated to investigate their properties under electromagnetic forces in an external magnetic field of up to 17.2 T. While REBCO coils were successfully operated under electromagnetic forces over 200 MPa, some showed degradation after quenching. To develop high-temperature superconducting (HTS) magnets, the reasons for the degradation of REBCO coils should be investigated. In this study, the degraded REBCO coils were carefully rewound. The critical current ( I c ) of the rewound REBCO conductor was measured to check the damaged parts in the degraded REBCO coils, and the possible causes for the degradation were discussed.