Current distribution measurement in YBCO thin film for a superconducting fault current limiter

Current distribution in the superconducting film for a resistive fault current limiter is important, because it influences AC loss and a uniformity of S/N transition. The lateral current distribution of the film was reconstructed from the magnetic field distribution which is measured by multiple Hall probes. The following results were obtained. (1) Non-uniform current distribution in the superconducting film was observed when the current was less than 1.3 times of critical current (I-c). (2) The current in a superconducting film was uniform when the current was much higher than I-c. The current can be considered uniform when the film works as a fault current limiter, because the SIN transition starts about twice of I-c. (3) The validity of the measurement was verified by the comparison with the electric circuit simulation. (C) 2003 Elsevier Science Ltd. All rights reserved.