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 (Ic) in YBa2Cu3O7-\delta (YBCO)-coated conductors by using a permanent magnet (Sm2Co17). This Ic measurement method is based on the repulsive force (Fr) between the magnet and the shielding current in high-temperature superconductor-coated conductors. We measured Fr using a high-resolution load sensor and found that accurate Fr could be determined without the effect of thick copper film on the YBCO thin film and Hastelloy tape of the substrate. We can determine Ic from Fr0, which is the maximum repulsive force determined from an extrapolated value of the Fr vs. L curve for L=0\ \ mm, described in our previous paper [1]. We show that the permanent magnet method can be used to determine the longitudinal Ic 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 Ic distribution of long-scale coated conductors. [ABSTRACT FROM AUTHOR]