Study on relation between AC characteristics and critical current distribution in YBCO tape

We measured AC transport current loss of a high current density YBCO tape conductor. The tape conductor was made by depositing YBCO thin layer of similar to 1 mu m thick on a LaAlO3 single crystal substrate and its critical current was around 100A at 0T and 77K, The loss data deviated from the Norris curves for the elliptical and strip models. We made an analytical model to numerically calculate the AC transport current loss. In the model, critical current density (J(c)) distribution in the wire cross section is taken into consideration. It is shown by the analysis based on the model that the deviation of the measured AC loss from the Norris equations is due to inhomogeneous J(c) distribution in the cross section of the tape. The J(c) distribution was investigated by subdividing the YBCO layer along the longitudinal direction. The results of the investigation are compared with the J(c) distribution deduced from the analysis. The loss data showed frequency dependency, which can be explained by assuming that the loss has hysteretic and eddy-current-like loss components.