Thermal conductivity gauge

Patent metadata

Field	Value
Publication number	US-10845263-B2
Application number	US-201815955266-A
Country	US
Kind code	B2
Filing date	Apr 17, 2018
Priority date	Apr 17, 2018
Publication date	Nov 24, 2020
Grant date	Nov 24, 2020

Abstract

A thermal conductivity gauge measures gas pressure within a chamber. A sensor wire and a resistor form a circuit coupled between a power input and ground, where the sensor wire extends into the chamber and connects to the resistor via a terminal. A controller adjusts the power input, as a function of a voltage at the terminal and a voltage at the power input, to bring the sensor wire to a target temperature. Based on the adjusted power input, the controller can determine a measure of the gas pressure within the chamber.

First claim

What is claimed is:

1. A thermal conductivity gauge for measuring gas pressure, comprising:
a sensor wire within a chamber coupled to a terminal and a ground;
a resistor coupled between the terminal and an electrical input receiving a power input;
a controller configured to 1) apply the power input to the resistor; 2) adjust the power input, as a function of a voltage at the terminal and a voltage at the electrical input, to bring the sensor wire to a target temperature; and 3) determine a measure of gas pressure within the chamber based on an adjusted power input at the target temperature.

2. The gauge of claim 1 , wherein the resistor and the sensor wire have an equivalent resistance at the target temperature.

3. The gauge of claim 1 , wherein the sensor wire is coupled to a grounded envelope encompassing a volume of the chamber.

4. The gauge of claim 3 , wherein the sensor wire is coupled to the envelope via a shield extending through the volume of the chamber.

5. The gauge of claim 1 , wherein the controller is further configured to 1) determine a compensation factor based on an envelope temperature external to the chamber and 2) determine the measure of gas pressure as a function of the compensation factor.

6. The gauge of claim 1 , wherein the resistor is a first resistor, and further comprising a second resistor and a switch connected in parallel with the first resistor, the controller configured to selectively enable the switch.

7. The gauge of claim 1 , further comprising an ion gauge within the chamber.

8. The gauge of claim 7 , wherein feedthroughs of the thermal conductivity gauge and the ion gauge extend through a common feedthrough flange coupled to the chamber.

9. The gauge of claim 8 , wherein the thermal conductivity gauge occupies a single feedthrough of the feedthrough flange, the terminal being the single feedthrough.

10. The gauge of claim 7 , wherein the controller is configured to selectively enable the ion gauge in response to detecting the measure of gas pressure being below a target threshold.

11. The gauge of claim 7 , wherein the controller is further configured to determine a compensation factor based on heat generated by the ion gauge, the controller configured to determine the measure of gas pressure as a function of the compensation factor.

12. The gauge of claim 7 , wherein the controller is configured to selectively disable the ion gauge in response to detecting the measure of gas pressure being above a target threshold.

13. The gauge of claim 1 , wherein the sensor wire is supported within a removable housing extending between the terminal and the ground.

14. A method of measuring gas pressure, comprising:
applying a power input through a resistor and sensor wire connected in series, the sensor wire being coupled to a terminal and a ground within a chamber, the resistor being coupled between the terminal and an electrical input receiving a power input;
adjusting the power input, as a function of a voltage at the terminal and a voltage at the electrical input, to bring the sensor wire to a target temperature; and
determining a measure of gas pressure within the chamber based on an adjusted power input at the target temperature.

15. The method of claim 14 , wherein the resistor and the sensor wire have an equivalent resistance at the target temperature.

16. The method of claim 14 , wherein the sensor wire is coupled to a grounded envelope encompassing a volume of the chamber.

17. The method of claim 16 , wherein the sensor wire is coupled to the envelope via a shield extending through the volume of the chamber.

18. The method of claim 14 , further comprising 1) determining a compensation factor based on an envelope temperature external to the chamber, and 2) determining the measure of gas pressure as a function of the compensation factor.

19. The method of claim 14 , wherein the resistor is a first resistor, and further comprising selectively connecting a second resistor in parallel to the first resistor based on the voltage at the terminal.

20. The method of claim 14 , further comprising selectively enabling an ion gauge in response to detecting the measure of gas pressure being below a target threshold.

21. The method of claim 14 , further comprising determining a compensation factor based on heat generated by an ion gauge, the measure of gas pressure being determined as a function of the compensation factor.

22. The method of claim 14 , wherein the sensor wire is supported within a removable housing extending between the terminal and the ground.

23. A thermal conductivity gauge for measuring gas pressure, comprising:
a circuit comprising a sensor wire and a resistor coupled in series, the sensor wire being positioned within a chamber; and
a controller configured to 1) apply a power input to the circuit; 2) adjust the power input, as a function of a voltage across one of the sensor wire and the resistor, to bring the sensor wire to a target temperature; and 3) determine a measure of gas pressure within the chamber based on an adjusted power input at the target temperature.

Assignees

• Mks Instr Inc

Inventors

• Brucker Gerardo A
• Swinney Timothy C

Classifications

• G01L21/14

  using thermocouples · CPC title

• G01L21/10

  by measuring variations in the heat conductivity of the medium, the pressure of which is to be measured · CPC title

• G01L9/025 Primary

  with temperature compensating means (non electric temperature compensating means G01L19/04) · CPC title

• G01L9/0002

  using variations in ohmic resistance (G01L9/0051 takes precedence) · CPC title

• G01L9/00

  Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements {(G01L11/004 takes precedence)}; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means (measuring differences of two or more pressure values G01L13/00; measuring two or more pressure values simultaneously G01L15/00) · CPC title