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, epsiv _irr.t. , was ~0.6%. The critical strain defined by the 95% I _c retention criterion was 1.4% which was located within the irreversible limit. The n-value-thetas behavior in the YBCO CC tape was similar to the I _c /I _c0 -thetas behavior.