| 摘要 |
PROBLEM TO BE SOLVED: To provide a molecular pump capable of easily and accurately changing conductance of a gas flow passage. SOLUTION: A relief ring board 13 for changing conductance is provided in the vicinity of an annular molecular suction part of a thread groove pump NP. A cylindrical part 4N is integrally attached to a lower part of a rotor 4 of the molecular pump, and a stator ring 9 is provided on an outer peripheral face of the cylindrical part 4N so as to oppose to the outer peripheral face of the cylindrical part 4N in the vicinity thereof. The annular pressure regulation ring board 13 is placed on the upper part of the stator ring 9. The annular pressure regulation ring board 13 is arranged in the vicinity of an inlet of a spiral groove provided on the stator ring 9 so as to oppose to the inlet, and is reciprocated with respect to the thread groove pump NP due to action of electromagnets 14, 15. Owing to this reciprocation movement, the conductance is changed and adjusted. Since the annular pressure regulation ring board 13 is reciprocated movement in a non-contact state and no sliding part is provided, no dust is generated from inside of the molecular pump. COPYRIGHT: (C)2006,JPO&NCIPI
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