Heat Transfer Property of Bi-2223/Ag Tape Impregnated with Solid Nitrogen near Triple Point

Heat transfer property of Bi-2223/Ag multifilamentary tape impregnated with solid nitrogen was investigated by measuring the voltage and temperature traces on the tape. Solid nitrogen was produced by two different methods: i.e., one by conduction cooling with GM cryocooler, and another by evacuation with rotary vacuum pump. The heat transfer coefficient between the tape and the solid nitrogen was estimated based upon the numerical simulation. It was shown that the equivalent heat transfer coefficient of the tape impregnated with solid nitrogen made by conduction cooling at a very slow cooling rate was more than six times larger than that made by evacuation.