Improvement of dissipative property in HTS coil impregnated with solid nitrogen

Dissipative property of high-Tc superconducting (HTS) coil impregnated with solid nitrogen was investigated. Small HTS solenoid coil was fabricated with the use of Bi-2223/Ag multifilamentary tape. Nitrogen was solidified by conduction cooling with Gifford-Macmafon cryocooler at cooling rate of 1 mK s-1. Voltage as well as temperature of the coil was measured by applying the thermal disturbance and bias current. It was shown that the dissipation was reduced drastically by impregnating with solid nitrogen. Furthermore, the properties were also improved by pressurization in the sample chamber. This pressure effect may be due to the suppression of sublimation at the interface between the solid nitrogen and the coil