単結晶基板上の高温超電導薄膜のクエンチ伝播速度

Abstract

We have performed precise, experimental and theoretical studies of the quench propagation velocities of the YBa2Cu3Ox (YBCO) high-temperature superconducting film prepared on oxide single-crystal substrates by pulsed laser deposition. In the experimental studies, we determined the quench propagation velocities using strip-shaped YBCO films prepared on LaAlO3 single-crystal substrate with many voltage terminals. That is, the quench propagation velocities were measured from the time that the voltage occurred at each terminal after quenching in part of the strip by a heater. We previously examined the influence of the temperature increase by the heater in order to estimate the correct value of the quench propagation velocity. We then used the data obtained in the region of small temperature increase by the heater. The quench propagation velocities of YBCO film obtained in this study were lower than that of the metallic superconducting wire by an order of 2-3. In a theoretical analysis, the quench propagation velocities were found to be expressed by a function of the specific heat, the density and the thermal conductivity of the substrate, a temperature difference between the operation temperature and Tc, the strip width of the superconducting film and the power of joule heating for the unit area. The theoretical estimations were in good agreement with the obtained quench propagation velocities from this experiment. Therefore, the theoretical analysis in this study is appropriate for the quench propagation characteristics of the superconducting film, and the quench propagation velocity can be estimated when the experimental conditions are determined.