| 摘要 |
PROBLEM TO BE SOLVED: To provide a dilution refrigerating machine capable of lowering an achieving temperature, having high operability and capable of being automatically operated. SOLUTION: This dilution refrigerating machine is constituted by successively disposing a circulation pump for a<SP>3</SP>He gas disposed outside a cryostat, a pre-cooling refrigerating machine provided with a cold generating portion disposed in the cryostat, a 1K stage for liquefying<SP>3</SP>He flowing therein from the inflow side of the<SP>3</SP>He gas, a JT heat exchanger, a fractional distillation chamber and a mixing chamber of<SP>3</SP>He and<SP>4</SP>He as a low-temperature output portion which are successively positioned in the cryostat. The circulation pump disposed outside the cryostat and the mixing chamber disposed in the cryostat are made to communicate with each other and connected by a<SP>3</SP>He main supply passage, a bypass passage is formed in parallel with the main supply passage in a state of bypassing the JT heat exchanger disposed in the main supply passage, a flow channel opening and closing valve is disposed in the bypass passage, and the circulation of<SP>3</SP>He to the bypass passage is controlled by the opening and closing operation of the flow channel opening and closing valve. COPYRIGHT: (C)2009,JPO&INPIT
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