Apparatus and method for controlling pressure ratio in high vacuum vapor pumps
AssigneeVarian Associates, Inc.
InventorsCharles D. O'Neal, III, Leo J. Blumle, Marsbed Hablanian
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Abstract
A predetermined pressure ratio is maintained between a foreline and a load port of a vacuum diffusion pump including a bath of oil that is vaporized by a heater. A property of the pump is sensed to derive a signal indicative of the pressure ratio. The signal is compared with a set point value to derive an error signal that controls the amount of power continuously supplied by the heater to the oil bath. The sensed property can be the RMS power supplied by the heater, the heat supplied to the bath, or the density of vaporized fluid in the pump.
Claims16
Apparatus for maintaining a predetermined pressure ratio between an inlet port and an output port of a vacuum vapor pump having a source of fluid that is vaporized by a heater comprising sensing means responsive to a property of the pump indicative of the actual pressure ratio for deriving a signal indicative of the actual pressure ratio, and means responsive to the signal for controlling power continuously supplied by the heater to the fluid source so that the predetermined ratio is attained.
A method of maintaining a predetermined pressure ratio between an inlet port and an outlet port of a vacuum vapor pump having a source of fluid that is vaporized by a heater comprising sensing a property of the pump indicative of the pressure ratio, and controlling power continuously supplied by the heater to the fluid source in response to the sensed property to attain the predetermined ratio.
Dependencies are inferred from the claim text.