JPS6423062A - Cryogenic refrigerating machine - Google Patents

Abstract

PURPOSE: To make a 20K refrigerating machine repairable and exchangeable without raising the temperature of an object to be cooled by detachably attaching a vacuum adiabatic extension pipe incorporating the convection accelerating pipe of the refrigerating machine to the radiation shield of a refrigerating machine which is the object to be cooled. CONSTITUTION: The nitrogen gas and hydrogen gas respectively contained in 80K and 20K coolant containers 17 and 18 are condensed into condensates and stored in coolant containers 17 and 18 after flowing through a convection accelerating pipe 13. The refrigerant which flows in the containers 17 and 18 and vaporized by thermal loads ascend, reach a cold generating section through the outside of the pipe 13, and are again condensed. Thus the coolants are circulated. When the coolant gases of the nitrogen gas and hydrogen gas in the containers 17 and 18 are directly condensed by detachably attaching a vacuum adiabatic extension pipe 11 to the refrigerant containers 17 and 18 on radiation shields 15 and 16 sides which are objects to be cooled, the shields 15 and 16 which are attached to the containers 17 and 18 in excellent thermal contact states and have about 80K and 20K temperature levels can be maintained in cold states with high thermal efficiencies. When a 20K refrigerator 1 which is an object to be cooled becomes defective, therefore, the object can be exchanged while the object is in a cooled state, because the whole body of the refrigerator 1 can be pulled out for repair or exchange due to the interposed containers 17 and 18.