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.