| 摘要 |
PURPOSE:To enhance the efficiency of cooling, by laying by-pass pipes upward from a forward feed line, connecting the by-pass pipes to each other through a valve, and laying liquefied helium transfer pipes downward from the forward feed line. CONSTITUTION:By-pass pipes 20, 21 are laid upward from a forward feed line 6 and connected to each other through a by-pass valve 22. Transfer pipes 7-9 for feeding liquefied helium to cryopumps 10-12 are laid downward from the forward feed line 6. As a result, helium evaporated by heat having entered into the transfer pipes 7-9 is retrieved so as to feed only the liquefied helium to the cryopumps 10-12 to enhance the efficiency of cooling of the cryopumps.
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