‘Defect-irrelevant-winding’ no-insulation (RE)Ba 2 Cu 3 O 7 − x pancake coil in conduction-cooling operation

Abstract This paper reports experiment and simulation results of a ‘defect-irrelevant-winding (DIW)’ no-insulation (NI) (RE)Ba 2 Cu 3 O 7 − x pancake coil operated in a conduction-cooling environment at temperatures lower than 77 K. The key idea of the DIW high-temperature superconductor (HTS) winding technique, firstly proposed in 2016, is to wind an NI pancake coil with HTS tapes, on purpose , containing multiple ‘defects.’ Using the defect (flawed) HTS tapes, we expect to significantly lower the construction cost of a DIW HTS magnet in marginal sacrifice of the magnet performance. In this study, charging tests of a DIW coil were performed in a conduction cooling system by controlling the temperature of the second stage in a range of 20–65 K, to determine the maximum operable current that avoids thermal runaway of the test coil at a given temperature. Coil terminal voltages, center fie…