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

Nonuniformity of critical current, I_c 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 I_c 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 I_c distribution of REBCO HTS wire for the entire strain range. The statistical minimum I_c calculated from the Weibull distribution function decreased with increased tensile strain. The degree of I_c variation was observed to drastically increase when the applied tensile strain exceeded the irreversible strain of about 0.8%.