Critical current degradation behaviour of various REBCO tapes under uniaxial strain

REBCO coated tapes have become one of the most practical superconducting materials, which have been considered in the design of high-field magnets for fusion in the future. At present, several manufacturers are able to produce commercial REBCO tapes. During the fabrication and operation of REBCO magnets, REBCO tapes are subjected to tension, compression, bending, and torsion loads, resulting in applied strains. However, the critical current (Ic) of REBCO tape is strain dependence. Therefore, the clear Ic performance of a single REBCO tape under applied uniaxial strain is required before designing REBCO conductors/magnets in order to help select an appropriate tape specification and manufacturer. In this paper, several measurements of Ic and n-value versus applied uniaxial strain were performed on different kinds of REBCO tapes, which were produced by Shanghai Superconductor Technology and Fujikura at 77 K with self-field on the U-spring device. The width of the REBCO tape is from 3 mm to 5 mm, and the thickness of the substrate is from 25 mu m to 50 mu m. The results show that the Ic of most of the tapes are reversible under applied uniaxial compressive strain. The width of the tape and the thickness of the substrate affects the irreversible tensile strain limit. The n-value of the REBCO tape hardly depends on the strain condition.