TURBO-MOLECULAR PUMP

PROBLEM TO BE SOLVED: To provide a turbo-molecular pump for optimizing the capability of a thrust magnetic bearing by setting a gap to a storage space depending on the inclination of a thrust disc. SOLUTION: The turbo-molecular pump 1 comprises a rotor 15 to be rotationally driven by a motor 37, having a thrust disc 23 at the end, a plurality of radial magnetic bearings 29, 31 for holding the rotor 15 at a center position in the rotating direction, a lower split casing 9 having the storage space 25 storing the thrust disc 23, and the thrust magnetic bearing 27 provided in the storage space 25 for holding the thrust disc 23 and holding the rotor 15 in the axial direction. A gap between the storage space 25 and the thrust disc 23 in an outer peripheral portion 43 of the thrust disc 23 is larger than a gap between the storage space 25 and the thrust disc 23 in an inner peripheral portion 41 of the thrust disc 23. COPYRIGHT: (C)2005,JPO&NCIPI