| 摘要 |
PROBLEM TO BE SOLVED: To prevent pressure within a cryopump from becoming higher than atmospheric pressure when hydrogen is exhausted. SOLUTION: A control part 50 allows a first electromagnetic exhaust valve 38 to be opened so as to let a gas separation continer 36 be made vacuous, and also allows a second cryopanel 33 to be adjusted in temperature to 10K through 50K so as to let only hydrogen gas to be separated, and hydrogen gas within the gas separation container 36 is deluted by the use of nitrogen gas until its concentration will be less than an exposive limit concentration. And then, a second electromagnetic exhaust valve 40 is released so as to let hydrogen gas within the gas separation container 36 be discharged out to an ill effect remover 35. Thus as mention above, explosive hydrogen gas is exhausted so as to let pressure within a casing 34 be lower than atmospheric pressure. This constitution thereby can prevent hydrogen gas from leaking out to the side of a vacuum chamber 56, and also prevent it from being brought into contact with a vacuum meter 57 such as a B-A guage, an ion guage and the like so as to be exploded.
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