Fixing structure for fixing rotor to rotor shaft, and turbo molecular pump having the fixing structure

Abstract

Provided are a fixing structure for fixing a rotor to a rotor shaft, in which the contact state of the contact surfaces of the rotor shaft and the rotor is stabilized to thereby maintain the rotation balance of the rotor shaft and the rotor, making it possible to prevent oscillation, and a turbo molecular pump having such a fixing structure. On the outer peripheral portion of the upper surface of a fastening portion (), there is concentrically formed a rotor shaft () side contact surface () to be brought into contact with a rotor (). Further, in the inner periphery of the contact surface (), there is formed a spot facing portion () whose upper surface is recessed from the contact surface (). Thus, when the rotor shaft () is fastened to the rotor (), there is formed, at the portion where the spot facing portion () is formed, a gap () which has a depth corresponding to the depth of the spot facing portion () and which is between the contact surface () of the rotor () and the spot facing portion ().