Effect of the Bending Strain on the Inhomogeneity of Critical Current for YBCO Coated Conductors

The inhomogeneity of critical current in long superconducting tape is one of the factors affecting the performance of the superconducting magnet. We investigate the effect of the bending strain on the inhomogeneity of critical current for the YBCO-coated conductor by a Hall sensor array system. Two kinds of the commercial YBCO-coated conductor tapes, which are prepared by rolling-assisted biaxially textured substrate (RABiTS) and ion-beam-assisted deposition (IBAD), are used for measurement. The bending strain is applied to the coated conductor tapes, and the distribution of the perpendicular component of the remanent field in the direction along the tape length after bending is measured by a Hall sensor array. The local critical current of the tape is calculated through the method of calibration and the distribution of the critical current in the long tape is described by the Weibull function. The result shows that the inhomogeneity of critical current in the long tape is significantly increased when bending strain exceeds an irreversible strain. The change of the superconducting layer structure is believed to be the cause of the critical current inhomogeneity growth.