Critical current degradation Behavior in YBCO coated conductors under torsional strain

The I-c degradation behaviors of a YBCO coated conductor (CC) tape (RABiTS/MOD) was investigated using a sample holder which gives torsional angles to HTS tapes. The I-c degradation in YBCO CC tape under torsional strains occurred gradually which is a characteristic feature under torsion. Uniform torsional deformation was induced in the YBCO CC tape evident from the consistent I-c degradation behavior at each subsection along the longitudinal direction of the tape. Similar with the tension case, the reversible behavior of I-c under torsional loading was found. The irreversible strain, epsilon(irr.t.), was similar to.6%. The critical strain defined by the 95% I-c retention criterion was 1.4% which was located within the irreversible limit. The n-value-theta behavior in the YBCO CC tape was similar to the I-c/I-c0-theta behavior.