Application of high-tc superconductor to current limiting devices

Resistive characteristics of YBa2Cu3O7-x superconducting thin film quenched by a current were investigated. The thin films were prepared on MgO substrates by the laser ablation method and currents of different wave forms were fed to it for few tens milliseconds in a liquid nitrogen to measure a temporal resistance. A resistance appeared quickly above a critical current then increased to about 8Q within few milliseconds which depended on an input power to the film. To investigate characterisites of the current-quenched superconducting film, a 1-dimensional heat transfer equation was numerically solved using a finite-difference method. Comparing these experimental and numerical results it was found that non-uniformities in a current density or a temperature may exist in the quenching thin film.