Variation of Local Critical Current Due to Mechanical Strain in RCE-REBCO Coated Conductors

Nonuniformity of critical current, Ic is one of the most important factors to be considered for the practical applications of high-temperature superconducting (HTS) REBCO coated conductors. To investigate the variation of Ic due to mechanical strain, local critical currents were measured at various tensile strain values from 0 to 1.2% for brass-laminated GdBCO tapes at 77 K, and analyzed using the Weibull distribution function. Measured local critical currents vary and decrease significantly at strain levels above about 0.8%. The Weibull function with three parameters turned out to be applicable for describing the Ic distribution of REBCO HTS wire for the entire strain range. The statistical minimum Ic calculated from the Weibull distribution function decreased with increased tensile strain. The degree of Ic variation was observed to drastically increase when the applied tensile strain exceeded the irreversible strain of about 0.8%.