| 摘要 |
PURPOSE:To enable gas removal to be performed quickly by providing a purge- gas discharge section, which have a plurality of outgassing parts designed to face at least a charcoal panel, on a means for supplying purge gas to a cryopanel and the charcoal panel. CONSTITUTION:On the upper end of a pump casing 1 a refrigerator 2 is installed, and within the pump casing 1 a plurality of cooling stages 3, 4, which are to be cooled by the refrigerator 2, are arranged. In addition, on each of the cooling stages 3, 4 cryopanels 5, 6 are fixed respectively, and on the cooling stage 4 a charcoal panel 7 is fixed additionally. In the above, a purge-gas discharge section 12 is provided so as to face the panel 7. Said discharge section 12 is made up in a manner where a purge-gas induction pipe 10 is extended into the pump casing 1 and wound spirally around the panel 7 through a fixed clearance 13, and on its surface opposite to the panel 7 a plurality of out-gassing ports 14 are formed.
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