JPS6161272B

PURPOSE:To recover rapidly evaporating helium gas at a low temperature without cooling it to room temperature once. CONSTITUTION:An evaporation helium He generated by normal electroconductive displacement of super electroconductive magnet gives rise to a temperature gradient ranging from 10k to 250k in cryostat during the time while it departs from a liquid surface 13 and reaches a recovery gate 7. During the time when this temperature gradient is taking place, a recovery gate 15 of a low-temperature gas recovery pipe 14, which is thermally insulated by vacuum, etc., is arranged at a point which is lower in temperature than liquefied nitrogen. He, which was thus recovered at a low temperature, is made to pass through a switch valve 16 to be insulated, cooled by the liquefied nitrogen and stored in a vacuum or low-pressure low-pemperature recovery tank 17. At this time, the valve 16 is closed to cool He to room temperauture by a heatexchanger 19, and He gas is recovered by a vacuum pump 20. The tank 17 becomes vacuum or low pressure to be prepared for next turn of rapid generation of the gas. By generation of the gas, the valve 16 is opened and a valve 21 is closed. It is possible, in this way, to reduce volume by one-fourth for recovery of gas of the same amout, improve stability of the super electroconductive magnet and increase cooling speed.