| 摘要 |
PURPOSE:To enable the stable operation of a cryopump, which is driven under both a stationary operation and a precooling regenerating operation mixed together, to be obtained easily by forcing supercritical pressure helium to circulate within the cryopump. CONSTITUTION:A supply piping 33 for the stationary operation and a return piping 34 for the stationary operation are connected through heaters 41a-41d and flow control valves 31a-31d to cryopumps 21a-21d respectively. These two pipings 33, 34 are connected to each other through a supercritical pressure helium circulator 32, which forces supercritical pressure helium to circulate through the pipings for stationary operation of the system. In addition, in the case the cryopump 21d to be regenerated, the heater 41d is operated with the flow control valve 31d closed and a valve 35 opened so that the helium gas is heated to high temperatures and then circulated within the cryopump 21d for its regenerating operation. The heated helium gas which finished the circulation as above is returned through a piping 36 to a refrigerator system 42.
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