Compact electrostatic ion pump

Patent metadata

Field	Value
Publication number	US-11569077-B2
Application number	US-201816629528-A
Country	US
Kind code	B2
Filing date	Jul 11, 2018
Priority date	Jul 11, 2017
Publication date	Jan 31, 2023
Grant date	Jan 31, 2023

Abstract

The disclosure includes an outer electrode and an inner electrode. The outer electrode defines an inner volume and is configured to receive injected electrons through at least one aperture. The inner electrode positioned in the inner volume. The outer electrode and inner electrode are configured to confine the received electrons in orbits around the inner electrode in response to an electric potential between the outer electrode and the inner electrode. The apparatus does not include a component configured to generate an electron-confining magnetic field.

First claim

What is claimed is:

1. An apparatus, comprising:
an outer electrode defining an inner volume and a central axis extending from a top of the outer electrode to a bottom of the outer electrode, wherein the outer electrode is configured to receive injected electrons through at least one aperture, and wherein the outer electrode comprises a wall defining an inner surface curved toward the central axis near the top and the bottom of the outer electrode; the at least one aperture being disposed on a curved portion of said inner surface curved toward the central axis; and
an inner electrode positioned in the inner volume,
wherein the outer electrode and inner electrode are configured to electrostatically confine the received electrons in orbits around the inner electrode in response to an electric potential between the outer electrode and the inner electrode, and
wherein the apparatus does not include a component configured to generate an electron-confining magnetic field.

2. The apparatus of claim 1 ,
wherein the inner electrode is positioned at about the central axis.

3. The apparatus of claim 1 ,
wherein the wall defines the at least one aperture extending through the wall, and
wherein the at least one aperture defines a direction of travel of the electrons around the central axis.

4. The apparatus of claim 2 ,
wherein the at least one aperture is positioned proximate at least one of the top or the bottom of the outer electrode, and
wherein a diameter of the inner surface at an axial middle of the outer electrode is greater than each of a diameter of the inner surface at the top of the outer electrode and a diameter of the inner surface at the bottom of the outer electrode.

5. The apparatus of claim 3 ,
wherein the inner surface of the outer electrode comprises a getter material configured to adsorb gases from the inner volume, and
wherein the inner surface is configured to shield adsorbed gases from ions.

6. The apparatus of claim 1 , further comprising a cylindrical grid positioned between the outer electrode and the inner electrode.

7. The apparatus of claim 5 ,
wherein the wall comprises a plurality of fins oriented substantially parallel to the central axis, and
wherein each of the plurality of fins is axially rotated in the direction of travel of the electrons.

8. The apparatus of claim 3 ,
wherein the wall is segmented, and
further comprising an enclosure outside the outer electrode.

9. The apparatus of claim 8 ,
wherein the inner surface of the outer electrode comprises a first getter material, and
wherein an inner surface of the enclosure comprises a second getter material, different from the first getter material.

10. The apparatus of claim 3 ,
wherein a shape of the inner surface of the outer electrode is generally cylindrical, barrel-shaped, egg-shaped, or spherical, and
wherein the shape of the inner surface of the outer electrode is configured to improve operation of the apparatus.

11. The apparatus of claim 2 , further comprising:
a top end cap proximate to the top of the outer electrode; and
a bottom end cap proximate to the bottom of the outer electrode,
wherein the top end cap and bottom end cap are configured to receive a negative potential, and
wherein each of the top end cap and the bottom end cap is axially spaced from the outer electrode to permit background gasses from outside the ion pump to enter into the inner volume.

12. The apparatus of claim 1 , wherein the apparatus has an outer volume of less than 30 cubic centimeters.

13. A system, comprising:
an electron source configured to inject electrons;
an electrode assembly coupled to the electron source, wherein the electrode assembly comprises:
an outer electrode defining an inner volume and a central axis extending from a top of the outer electrode to a bottom of the outer electrode, wherein the outer electrode is configured to receive injected electrons through at least one aperture, and wherein the outer electrode comprises a wall defining an inner surface curved toward the central axis near the top and the bottom of the outer electrode; the at least one aperture being disposed on a curved portion of said inner surface curved toward the central axis; and
an inner electrode positioned in the inner volume,

wherein the electrode assembly is configured to electrostatically confine the electrons within an internal volume defined by the electrode assembly,
wherein the outer electrode and inner electrode are configured to electrostatically confine the received electrons in orbits around the inner electrode in response to an electric potential between the outer electrode and the inner electrode,
wherein the electron source is coupled to the electrode assembly and configured to inject the electrons through the at least one aperture, and
wherein the system does not include a component configured to generate an electron-confining magnetic field.

14. The system of claim 13 ,
wherein the electron source is a Spindt cathode electron beam source, and
wherein the Spindt cathode electron beam source is configured to inject the electrons at a divergence half-angle less than 25 degrees Celsius (° C.) horizontally.

15. The system of claim 13 , further comprising a controller configured to:
control the electric potential between the outer electrode and the inner electrode; and
control an electron energy of the electron source.

16. The system of claim 13 , wherein the outer electrode is grounded.

17. The system of claim 15 , wherein the controller is configured to control a power source coupled to the inner electrode to produce the electric potential between the inner electrode and the outer electrode.

18. The system of claim 17 , wherein the electric potential is configured to produce ion energies in the inner volume between 500 electron volts (eV) and 3 kiloelectron volts (keV).

19. The system of claim 15 , wherein the controller is further configured to control a second power source to change an injection energy of the electrons.

20. The system of claim 15 ,
wherein the at least one aperture includes a mesh over an inner opening of the at least one aperture, and
wherein the controller is further configured to:
control the electron source to inject the electrons through pulsations; and
apply a voltage to the mesh based on the pulsations.

21. The system of claim 13 , wherein the injected electrons have an effective time of flight of greater than 0.1 microseconds (μs).

22. The system of claim 13 , further comprising a sealed housing configured to contain the outer electrode, the inner electrode, and the electron source, wherein the sealed housing defines a sensor, and wherein the sensor further comprises one or more chambers fluidically coupled to the inner volume of the cylindrical outer electrode.

23. The system of claim 22 , wherein the chamber is a cold atom physics chamber.

24. The system of claim 22 , wherein the sensor further comprises an alkali source.

25. The system of claim 22 , wherein the sensor further comprises a getter.

26. The system of claim 22 , wherein the sensor has a volume less than 25 cubic centimeters.

27. The system of claim 22 , wherein the sensor is part of at least one of an atomic clock, a gyroscope, an accelerometer, a navigation unit, or an ultra-low vacuum sensor.

28. A method, comprising:
receiving, b

Assignees

• Stanford Res Inst Int

Inventors

• Mcbride Sterling Eduardo
• Michalchuk Joey J
• Holland Christopher E
• Chaudhary Ashish
• Chan Winston K

Classifications

• F04B37/02

  for evacuating by absorption or adsorption · CPC title

• B03C3/40

  Electrode constructions · CPC title

• H01J41/12 Primary

  Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps · CPC title

• H01J41/00

  Discharge tubes for measuring pressure of introduced gas {or for detecting presence of gas}; Discharge tubes for evacuation by diffusion of ions · CPC title

• F04B37/14

  to obtain high vacuum · CPC title