Mark O Foreman

US Patent:

53867084, Feb 7, 1995

Filed:

Sep 2, 1993

Appl. No.:

8/115860

Inventors:

Huruli D. Kishorenath - San Jose CA
Johan E. de Rijke - Cupertino CA
Mark O. Foreman - Stockton CA

Assignee:

Ebara Technologies Incorporated - Santa Clara CA

International Classification:

B01D 800

US Classification:

62 555

Abstract:

Apparatus and method for vacuum pumping an enclosed chamber includes a cryogenic pumping device in fluid communication with the chamber for removing gases from the chamber. The cryogenic pumping device includes a cooled pumping surface and an expander for expanding a compressed gas and thereby cooling the pumping surface. The vacuum pumping apparatus further includes a sensor for sensing an operating parameter, such as temperature, of the cryogenic pumping device and a controller responsive to the sensor for controlling the operating speed of the expander to produce a desired value of the operating parameter. Typically, the sensor is a temperature sensor, and the controller controls the speed of the expander motor.