Cold cathode ionization gauge control for vacuum measurement
AssigneeVarian Associates, Inc.
InventorCharles D. O'Neal, III
Life of this patent
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Abstract
A cold cathode ionization gauge controller utilizing a periodically varying potential across the gauge tube at higher pressure and substantially constant potential at low pressure provides a wide-range pressure measurement capability from about 10.sup.-.sup.1 to about 10.sup.-.sup.7 torr.
Claims11
A controller circuit for a cold cathode ionization gauge tube comprising
- means for supplying a unidirectional electric field of periodically varying amplitude within said gauge tube for high pressure conditions in said tube, the peak amplitude of said periodic electric field exceeding the threshold electric field required to initiate electrical discharge within said gauge tube at a desired low pressure extreme, and
- means for extending the time interval during which said field exceeds the discharge threshold of said gauge tube for low pressure conditions in said gauge tube.
The method of measuring pressure with a cold cathode ionization gauge tube, said method comprising the steps of applying a potential across said gauge tube, said potential being periodically varying in the substantially high presssure domain of the range of said gauge tube, and altering the periodicity of said potential to a more constant value in the substantially low pressure domain of the range of said gauge tube.
A control circuit for supplying a variable load, comprising means for supplying a periodic electric field of relatively high peak amplitude in response to relatively high current consumption of the load and for supplying an electric field of more nearly constant amplitude in response to relatively lower current consumption of the load, whereby power consumption at relatively high current is limited for high current loads and yet high potential is available for relatively long periods at lower current load.
Dependencies are inferred from the claim text.