Abstract: A turbo vacuum pump has a rotor and magnetic bearings. The magnetic bearings are held in a housing having a suction port and an exhaust port, and support the rotor rotatably. A peripheral flow pump stage and screw pump stage are formed in the rotor, so that the pressure at the exhaust port can be at or near atmospheric pressure level. Before starting the turbo vacuum pump, the magnetic bearings are operated to displace a rotor position and to scrape off the reaction products which have deposited inside the pump. In addition, before starting the turbo vacuum pump, a stator of the pump is heated up to decrease a binding force of the reaction products. Therefore, the pump can be restarted, even if the rotor has locked by the solidification of deposited reaction products formed during stopping of the pump.

Abstract: A radiation generator extracts a synchrotron radiation beam from an electron storing ring, through a high-vacuum atmosphere in a beam duct, while preventing loss of the high-level vacuum. A multistage axial-flow arrangement is interposed in the beam duct. Stators and rotors having a plurality of blades are alternately disposed along the axial flow arrangement. The tilt angle of some of the blades of each stator is variable. Loss of the high-level vacuum in the electron storing ring is prevented by tilting the blades having a variable tilt angle so that gas remaining in the rest of the system does not flow upstream to the high-vacuum side of the beam duct at times when the radiation beam is not passing through the beam duct.

Abstract: An axial-flow molecular pump has a first active magnetic bearing for axially supporting and controlling a pump member comprised of a set of permanent magnets on the upper end of the pump member cooperating with a set of permanent magnets fixedly mounted at the upper end of a pump housing, a first electromagnet coacting with the sets of permanent magnets and operative when energized for controlling the axial position of the pump member, and an axial sensor for detecting axial displacement of the pump member and accordingly controlling the energization of the first electromagnet. A second active magnetic bearing for radially supporting and controlling the pump member comprises a second electromagnet operative when energized for controlling the radial position of the pump member, and a radial sensor for detecting radial displacement of the pump member and accordingly controlling the energization of the second electromagnet.

Abstract: A turbo-molecular pump characterized in that three out of five degrees of freedom except the rotation around the rotational axis of a shaft are actively controlled constrainingly by a pair of magnetic radius direction bearings and a pair of magnetic axial bearings, a bell-shaped rotor provided to cover the whole of magnetic bearing and a shaft which is supported by a magnetic bearing passively constraining the remaining two degrees of freedom, and said rotor is rotated at high speed by an inner-rotor type of a driving motor provided between a radius direction bearing and axial bearing.