Characteristics of Impregnated Pancake Coils Fabricated Using REBCO Coated Conductors

REBCO coated conductors are expected high performance in superconducting applications because of their high current density and high mechanical strength. However, in order to use these conductors in superconducting applications, a technique is required for fabricating impregnated REBCO coils without degradation. In this work, we fabricated six pancake coils without degradation using wounded REBCO coated conductors. These conductors were laminated with a copper tape as a stabilizer, and were fabricated by the IBAD/PLD method. In addition, we evaluated the V-I characteristics and n-values of the coils in liquid nitrogen and compared the calculated and measured values for the critical current (I-c) of the REBCO coated conductors. The measured I-c of the coils were in good agreement with the calculated ones. Furthermore, we fabricated a stacked coil using an approximately 190 m long REBCO coated conductor and evaluated the stability of the stacked coil at 77, 60 and 50 K under conduction-cooled condition. The thermal runaway current of the stacked coil was 166.4 A, and the central magnetic field was 1.27 T at 50 K.