Molecular pump for forming a vacuum

摘要

A clearance between a rotor and a stator is adjusted by forming the outer peripheral surface of the rotor and the inner peripheral surface of the stator into a conical shape, and relatively moving the rotor and the stator in the thrust direction. When the rotor is rotatably supported by a magnetic bearing, the magnitude of the clearance between the rotor and the stator may be adjusted by offsetting the position at which the rotor is held in the thrust direction. The stator may be moved in the thrust direction by forming the bottom of the stator of electrostrictive material and expanding and contracting the electrostrictive member. When the outer peripheral surface of the rotor and the inner peripheral surface of the stator is cylindrical, the inner diameter of the stator may be increased and decreased by forming a part of the stator of electrostrictive material.