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Ōsaka, Japan

Ogiwara N.,Japan Atomic Energy Agency | Yanagibashi T.,Japan Atomic Energy Agency | Hikichi Y.,Japan Atomic Energy Agency | Nishikawa M.,Japan Atomic Energy Agency | And 2 more authors.
Vacuum | Year: 2013

To safely use turbo-molecular pumps (TMPs) in a magnetic field, it is necessary to reduce the eddy current induced in a rotating rotor. Instead of adding a magnetic shield facility to the TMPs available in markets, we developed a TMP with a magnetic shield function by replacing the housing material of the TMP with a ferromagnetic substrate SUS430. Before and after machining, the SUS430 was vacuum-fired at 700 °C for 10 h in order to attain a good vacuum quality and recover its high magnetic permeability. The magnetic shield efficiency of the TMP with SUS430 housing was then examined. When a perpendicular magnetic field of 9 mT was applied, the field inside the TMP was reduced to less than 0.3 mT. Next, we confirmed that the developed TMP shows good performance in achieving an ultrahigh vacuum in magnetic fields of up to 9 mT. The limit of the magnetic shield efficiency for the developed TMP is also discussed. © 2012 Published by Elsevier Ltd. Source


Patent
Osaka Vacuum Ltd. | Date: 2013-08-27

A molecular pump includes a pump body provided with a turbo molecular pump portion, a control unit provided with a control portion and a power supply portion, and a cooling unit for cooling the pump body and the control unit. A first temperature detecting portion is provided in a first position, which is a position inside the control unit and has a low temperature. A second temperature detecting portion also serving as a humidity detecting portion is provided in a second position, which is a position inside the control unit and has a high temperature. The control portion controls the operation of the cooling unit in accordance with a relative humidity in the first position, calculated based on temperature information detected by the first temperature detecting portion and based on temperature information and humidity information detected by the second temperature detecting portion also serving as a humidity detecting portion.


Provided is a radial direction controller capable of handling changes in negative bearing stiffness according to the mounting orientation. This radial direction controller, which is a magnetic bearing device that lifts and supports a rotating body by electromagnets, is equipped with: a radial control circuit for controlling displacement of the axis of the rotating body in the radial direction; a negative bearing stiffness elimination circuit that is connected in parallel with the radial control circuit and outputs a signal about the negative bearing stiffness; converters that output current values for controlling the electromagnets, based on the output signals from these circuits; filters that extract the DC component from the current values; computing units that compute correction coefficients based on the extracted DC components and the bias current of the electromagnets; and multiplication units that multiply the computed correction coefficients with the signal output from the negative bearing stiffness elimination circuit.


Trademark
Osaka Vacuum Ltd. | Date: 2012-03-20

Vacuum pumps (machines).


Trademark
Osaka Vacuum Ltd. | Date: 2012-03-20

Vacuum pumps (machines).

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