Measurement of the Lateral Transport Current Distribution in YBCO Tape

Hall probe mapping was applied to the self-field of the YBCO superconducting tape with gradually increasing and decreasing transport current. The mapped data of magnetic field component perpendicular to the tape plane were used in inverse calculation of the lateral current distribution across the width of the tape for different current levels. The concept of longitudinal invariance of current distribution involved in calculation could be applied at least on local scale. Achieved current distribution profile can be to some degree attributed locally to a selected cross section of the tape. For the sample 4 mm wide we observed the change of initially convex profile of the transport current distribution at small currents to concave one during its gradual increase up to saturated region. This tendency to concave distribution was proved also for another 4 mm sample produced by the same producer, but two years later. Comparative measurements were made also for 12 mm wide tape. The producer was the same. This time we revealed however prevailing convex behavior of current profiles in region approaching the critical current. The reason for this discrepancy may be explained by technology applied.