Characteristics of epoxy-impregnated AC superconducting coils

Investigations of quench currents, stability and ac losses for several kinds of epoxy-impregnated ac superconducting coils are presented. As the first step, the temperature rise of epoxy-impregnated test coils wound with manganin heater wires were measured. From the results, it was demonstrated that the ac losses of 2-layer and 8-layer solenoidal superconducting coils and disc-type superconducting coils could be removed by the heat conduction through the epoxy without significant temperature rise, provided the thickness of the epoxy-impregnated layer was less than about 2 mm, and that the disc-type coil of 4 kVA or more could be feasible.