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.