Characteristics of conduction-cooled racetrack coils fabricated using REBCO coated conductor

Abstract: REBCO coated conductors having a performance greater than 300A/cm at 77K have been developed for superconducting applications. The conduction-cooled coils fabricated using REBCO coated conductors are expected to have the high performance because the specific heats of the constituent materials increases greatly with the operating temperature. From the point of view of the coil design using REBCO coated conductors, we must consider the critical current versus the magnetic field characteristics and their temperature dependence. In this study, we fabricated the two-layer stacked racetrack coil whose outer diameter was 92×172mm with 56 turns. The coil used the REBCO coated conductor, whose critical current was around 200A/5mm at 77K self field, manufactured by Fujikura Ltd. We compared with the calculated and measured the voltage distribution of one racetrack coil, which was attached with voltage taps each turn, at 77K in self field. We investigated the Ic of the two-layer coil at 65K and 50K under conduction-cooled conditions. The Ic values of the two-layer coil in self field using a criterion of 10−7 V/cm were achieved 220A at 65K and 386A at 50K, which the central magnetic fields were 0.13T at 65K and 0.23T at 50K, respectively. [Copyright &y& Elsevier]