Interrupted DC operation of thermocouple vacuum gauge
AssigneesSumitomo Heavy Industries, Ltd., SHI-APD Cryogenics, Inc.
InventorsJohn Borchers, Gary Ash, Paul Nickelsberg
Life of this patent
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Abstract
A direct current voltage to heat the sensor wire for powering and extracting a signal voltage from a thermocouple-type vacuum sensor. The direct current used produces a DC offset in the sensor output where the heating current flow is stopped for a short interval and the unbiased sensor voltage is then sampled and stored.
Claims16
A high vacuum cryopump system comprising:
- a direct current source controlled by an electronic controller;
- and
- a thermocouple vacuum gauge coupled to the direct current source to receive the direct current, the thermocouple vacuum gauge used to measure the pressure in the cryopump during operation and regeneration;
- where the direct current is interrupted before a thermocouple reading is taken.
A method of zeroing a vacuum gauge in a high vacuum cryopump system comprising an electronic controller employing direct current for operation of a thermocouple vacuum gauge used to measure a pressure in the cryopump during operation and regeneration where the thermocouple vacuum gauge uses direct current that is interrupted before a thermocouple reading is taken, when the pressure is less than 0.001 torr by one of:
- changing a constant in an equation that relates the thermocouple reading to pressure, and shifting the time when the reading is taken after said direct current is interrupted.
An electronic controller for a high vacuum cryopump, comprising:
- an arrangement for providing a direct current to a thermocouple vacuum gauge;
- and
- an arrangement for interrupting the direct current provided to the thermocouple vacuum gauge;
- wherein the thermocouple vacuum gauge is configured to measure the pressure in the cryopump during operation and regeneration.
An apparatus for determining a pressure in a high vacuum cryopump system comprising:
- a thermocouple arranged in a gauge tube,
- a circuit configured to provide direct current to the thermocouple and interrupt the direct current to take a reading, and
- an output means to read the pressure of the system.
A method of measuring a vacuum in a high vacuum cryopump system, comprising:
- applying a direct current to a thermocouple arranged in the vacuum to raise a temperature of the thermocouple;
- interrupting the direct current;
- and
- reading a voltage output of the thermocouple while the direct current is interrupted.
Dependencies are inferred from the claim text.