Detection of Critical Current Distribution of YBCO-Coated Conductors Using Permanent Magnet Method

We developed a non-destructive and contactless system for measuring the critical current (I c ) in YBa 2 Cu 3 O 7-δ (YBCO)-coated conductors by using a permanent magnet (Sm 2 Co 17 ). This I c measurement method is based on the repulsive force (F r ) between the magnet and the shielding current in high-temperature superconductor-coated conductors. We measured F r using a high-resolution load sensor and found that accurate F r could be determined without the effect of thick copper film on the YBCO thin film and Hastelloy tape of the substrate. We can determine I c from F r0 , which is the maximum repulsive force determined from an extrapolated value of the F r vs. L curve for L = 0 mm, described in our previous paper. We show that the permanent magnet method can be used to determine the longitudinal I c distribution and large-scale defects in YBCO-coated conductors. In addition, it turned out from this experiment that the permanent magnet method was effective to rapidly measure the longitudinal I c distribution of long-scale coated conductors.