| 摘要 |
PROBLEM TO BE SOLVED: To provide a molecular pump having controllable exhausting capability at a thread groove pump part. SOLUTION: For example, the outer periphery face of a rotor and the inner periphery face of a stator are formed to be conical, and a gap between the rotor and the stator is adjusted by relatively moving the rotor and stator in a thrusting direction. If the rotor is axially supported by a magnetic bearing, the size of the gap between the rotor and stator can be adjusted by offsetting the holding position of the rotor to the thrusting direction. The bottom of the stator is formed of an electrostrictive member, and the stator can be moved to the thrusting direction by expanding the electrostrictive member. If the outer periphery face of the rotor and the inner periphery face of the stator are cylindrical, the inner diameter of the stator can be made larger or smaller by forming a portion of the stator of the electrostrictive member.
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