Study on the Transport Current Characteristics of YBCO Coated Conductor According to Stabilization Layer

Abstract

The analysis of the steady and transient states is very important for the application of the superconducting wire to electric devices. Through many studies, the detailed evaluation technology for BSCCO wire, referred to as “the first-generation superconducting wire,” has been established to some extent. Meanwhile, the detailed analysis of the steady and transient states of YBCO thin-film wire, the second-generation wire that is increasingly being applied to more electric devices, is insufficient. Accordingly, in this study, the quench behavior at a below-critical temperature was evaluated, especially in the flux flow state, using two types of commercial YBCO thin-film wires, to determine the electric devices to which the wire can be applied, and to define its operating conditions. For this, YBCO thin-film wires with copper and stainless-steel stabilizer layers, which were manufactured considering the specific resistance and conductivity of the stabilizer layer, were prepared. The critical currents of the two wires were 85 A and 70 A, respectively, but their critical temperatures were identical at 90 K. The resistance values of both wires increased over time, within the range above the critical temperature, but they were different within the range below the critical temperature, according to the stabilizer layer. This can be an index that clearly represents the conducting and current-limiting characteristics of YBCO thin-film wire. Therefore, in this study, the two wires' current division characteristics were examined within the temperature range of 77 K (at which the liquid nitrogen starts to boil) to 90 K (the critical temperature) to determine which of the two wires was the conduction wire and which was the current-limiting wire. In addition, the conduction region was defined based on the trend of increase resistance below and above the critical temperature.