Thermal and electrical stabilities of solid nitrogen (SN2) cooled YBCO coated conductors for HTS magnet applications

Abstract

Recently, a cooling system using a solid cryogen such as solid nitrogen (SN2), was introduced for high temperature superconducting (HTS) magnet applications. In order to apply the SN2 cooling system successfully to HTS applications, it is essential to obtain sufficient data regarding the characteristics of the SN2-cooled YBCO-coated conductor (CC), including the thermal and electrical properties. Therefore, this study examined the effect of SN2 on the thermal/electrical stability of YBCO CC tape. The SN2 was produced by conduction cooling using a GM-cryocooler and cooled to 58 K. The voltages and temperatures of the YBCO CC tapes were measured while applying an over-current. The results showed that the thermal and electrical stability of the YBCO CC tape were improved considerably in the SN2 cooling system compared to that in the conduction cooling system.