Wireless thermionic sensor

Patent metadata

Field	Value
Publication number	US-9903767-B2
Application number	US-201414575628-A
Country	US
Kind code	B2
Filing date	Dec 18, 2014
Priority date	Dec 18, 2014
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

A thermionic sensor is disclosed. The sensor includes a sensor housing at least partially defining an emission chamber in which at least a partial vacuum is maintained; a cathode disposed in the emission chamber; an anode disposed in the emission chamber and spaced apart from the cathode; and an electrically conductive layer disposed in the emission chamber facing the anode and cathode. The thermionic sensor is configured to output a detection signal when the anode and cathode are at substantially the same temperature.

First claim

What is claimed is:

1. A thermionic sensor comprising:
a sensor housing at least partially defining an emission chamber in which vacuum conditions are maintained, the emission chamber having opposing first and second surfaces;
a cathode disposed in the emission chamber on the first surface;
an anode disposed in the emission chamber on the first surface, and spaced apart from the cathode; and
an electrically conductive layer disposed in the emission chamber on the second surface, facing the anode and cathode,
wherein the thermionic sensor is configured to output a detection signal when the anode and cathode are at substantially the same temperature.

2. The thermionic sensor of claim 1 , wherein the sensor housing comprises a substantially non-porous ceramic material.

3. The thermionic sensor of claim 1 , wherein the emission chamber is maintained at a pressure of less than about 100 micro Torr.

4. The thermionic sensor of claim 1 , wherein the cathode comprises tungsten alloyed with about 0.2% to about 5.0 wt % of a rare earth element, based on the total weight of the cathode.

5. The thermionic sensor of claim 4 , wherein the rare earth element comprises lanthanum.

6. The thermionic sensor of claim 1 , wherein the anode comprises substantially pure tungsten.

7. The thermionic sensor of claim 1 , wherein:
the sensor housing comprises a flexible portion configured to flex in response to an amount of ambient pressure applied to the sensor housing; and
the electrically conductive layer is attached to the flexible portion, such that a distance between the electrically conductive layer and the cathode and anode changes in accordance with the amount of ambient pressure.

8. The thermionic sensor of claim 1 , further comprising a refractory metal encasing the sensor housing.

9. The thermionic sensor of claim 1 , wherein the sensor is configured to detect the temperature or pressure of an ambient environment.

10. The thermionic sensor of claim 1 , wherein the anode comprises:
an outer anode disposed around the cathode; and
an inner anode disposed between the outer anode and the cathode, the inner and outer anodes being spaced apart from one another.

11. The thermionic sensor of claim 1 , wherein the sensor housing comprises:
a bottom plate upon which the cathode and the anode are disposed; and
a top plate disposed on the bottom plate and upon which the conductive layer is disposed.

12. The thermionic sensor of claim 11 , further comprising a spacer disposed between the top plate and the bottom plate.

13. The thermionic sensor of claim 11 , further comprising a substrate on which the sensor housing is disposed, the substrate comprising the substantially non-porous ceramic material.

14. The thermionic sensor of claim 11 , further comprising leads extending from the cathode and the anode to outside of the sensor housing.

15. The thermionic sensor of claim 1 , wherein:
one of the cathode and the anode is circular; and
the other of the cathode and the anode is C-shaped.

16. The thermionic sensor of claim 1 , wherein the cathode and the anode are spaced apart by a substantially constant minimum distance.

17. The thermionic sensor of claim 1 , further comprising a substrate, wherein,
the substrate and the housing cooperate to define the emission chamber, and
the anode and the cathode are disposed on the substrate.

18. A thermionic sensor comprising:
a sensor housing comprising a substantially non-porous ceramic material and at least partially defining an emission chamber that is maintained at a pressure of less than about 100 micro Torr;
a cathode disposed in the emission chamber;
an anode disposed in the emission chamber and spaced apart from the cathode; and
an electrically conductive layer disposed in the emission chamber facing the anode and cathode,
wherein the thermionic sensor is configured to:
apply a bias voltage between the cathode and anode; and
electrically float the conductive layer.

19. The thermionic sensor of claim 18 , wherein the thermionic sensor is configured to output a detection signal when the anode and cathode are at substantially the same temperature.

Assignees

• Palo Alto Res Ct Inc

Inventors

• Sahu Saroj Kumar
• Limb Scott
• Torres Francisco E

Classifications

• G01K7/40 Primary

  using ionisation of gases · CPC title

• G01L1/14

  by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators · CPC title

• G01K11/00

  Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 · CPC title

• G01L21/32

  using electric discharge tubes with thermionic cathodes · CPC title