Electron-beam spot optimization

Patent metadata

Field	Value
Publication number	US-10529529-B2
Application number	US-201715424270-A
Country	US
Kind code	B2
Filing date	Feb 3, 2017
Priority date	Apr 20, 2016
Publication date	Jan 7, 2020
Grant date	Jan 7, 2020

Abstract

An x-ray source can include an x-ray tube and a focusing-ring. The focusing-ring can at least partially encircle an electron-emitter, a cathode, an evacuated-enclosure, or combinations thereof. The focusing-ring can be located outside of a vacuum of the evacuated enclosure. The focusing-ring can adjust an electron-beam spot on a target material of the x-ray tube when moved along a longitudinal-axis extending linearly from the electron-emitter to the target material.

First claim

What is claimed is:

1. A method of tuning an electron-beam spot on a target material in an x-ray tube, the method comprising the following steps performed in the following order:
a) energizing the x-ray tube to cause:
i) electrical current to flow through a filament, causing emission of electrons from the filament to the target material;
ii) creation of the electron-beam spot where the electrons impinge on the target material; and
iii) emission of x-rays from the target material;

b) evaluating the electron-beam spot with respect to a predetermined characteristic by receiving the x-rays into a detector, determining an actual characteristic of the electron-beam spot, comparing the actual characteristic to the predetermined characteristic;
c) moving a focusing-ring along a longitudinal-axis of the x-ray tube to tune the electron-beam spot to the predetermined characteristic, the longitudinal-axis extending from the filament inside the x-ray tube to the target material; and
d) immovably fastening the focusing-ring with respect to the filament.

2. The method of claim 1 , wherein immovably fastening the focusing-ring includes:
a) inserting an adhesive into a gap between the focusing-ring and the x-ray tube;
b) tightening a set screw in the focusing-ring against the x-ray tube;
c) welding the focusing-ring onto the x-ray tube;
d) soldering the focusing-ring onto the x-ray tube;
e) clamping the focusing-ring onto the x-ray tube;
f) pinching the focusing-ring shut against the x-ray tube;
g) using a connector to fasten the focusing-ring to the x-ray tube;
h) interference fit between an interior of the focusing-ring and an exterior of the x-ray tube; or
i) combinations thereof.

3. The method of claim 1 , wherein moving the focusing-ring along the longitudinal-axis includes threading the focusing-ring on mating threads between an interior of the focusing-ring and an exterior of the x-ray tube.

4. The method of claim 1 , wherein:
a) the x-ray tube further comprises an evacuated-enclosure that electrically-insulates a cathode from an anode;
b) the focusing-ring at least partially encircles the evacuated-enclosure; and
c) the focusing-ring encircles the filament.

5. The method of claim 1 , wherein the focusing-ring encircles at least a portion of the filament.

6. The method of claim 1 , wherein the predetermined characteristic is electron-beam spot size, electron-beam spot shape, electron-beam spot location, or combinations thereof.

7. An x-ray source comprising:
a) an x-ray tube including:
i) an anode that is electrically-conductive and that includes a target material configured for production and emission of x-rays in response to impinging electrons;
ii) a cathode that is electrically-conductive and that includes a filament capable of emitting electrons towards the target material;
iii) an evacuated-enclosure attached to the cathode and the anode and that electrically-insulates the cathode from the anode;

b) a focusing-ring:
i) encircling the filament;
ii) including a relative-motion means for controlling motion of the focusing-ring with respect to the filament;
iii) located outside of a vacuum of the evacuated enclosure;
iv) capable of adjusting an electron-beam spot on the target material when moved along a longitudinal-axis extending linearly from the filament to the target material; and
v) fastened immovably onto the x-ray tube.

8. The x-ray source of claim 7 , wherein the relative-motion means includes mating threads between an interior of the focusing-ring and an exterior of the x-ray tube.

9. The x-ray source of claim 7 , wherein the focusing-ring is fastened immovably onto the x-ray tube by an adhesive, a set screw, a weld, a solder, a clamp, press-fit, or combinations thereof.

10. An x-ray source comprising:
a) an x-ray tube including:
i) an anode that is electrically-conductive and that includes a target material configured for production and emission of x-rays in response to impinging electrons;
ii) a cathode that is electrically-conductive and that includes a filament capable of emitting electrons towards the target material;
iii) an evacuated-enclosure attached to, and that electrically-insulates, the cathode from the anode;

b) a focusing-ring:
i) at least partially encircling the filament, the cathode, the evacuated-enclosure, or combinations thereof;
ii) being electrically-conductive;
iii) located outside of a vacuum of the evacuated enclosure;
iv) capable of adjusting an electron-beam spot on the target material if moved along a longitudinal-axis extending linearly from the filament to the target material; and
v) fastened immovably onto the x-ray tube.

11. The x-ray source of claim 10 , wherein the x-ray source further comprises mating threads between an interior of the focusing-ring and an exterior of the x-ray tube.

12. The x-ray source of claim 10 , wherein the focusing-ring is fastened immovably onto the x-ray tube by an adhesive, a set screw, a weld, a solder, a clamp, press-fit, or combinations thereof.

13. The x-ray source of claim 10 , wherein the focusing-ring completely encircles the cathode along the longitudinal-axis.

14. The x-ray source of claim 10 , wherein the focusing-ring is metallic and the focusing-ring encircles the filament.

15. The x-ray source of claim 10 , wherein an inner-diameter of the focusing-ring is between 8 millimeters and 30 millimeters.

16. The x-ray source of claim 10 , wherein the focusing-ring is electrically-coupled to the cathode.

17. The x-ray source of claim 10 , further comprising a power supply, the focusing-ring is electrically-insulated from the cathode, and the power supply is configured to maintain a voltage between the focusing-ring and the cathode of between 10 volts and 500 volts.

18. The method of claim 1 , wherein the detector automatically compares the actual characteristic to the predetermined characteristic.

19. The method of claim 1 , wherein moving the focusing-ring along the longitudinal-axis is performed automatically by a computer.

20. The x-ray source of claim 7 , wherein the relative-motion means includes mating threads between an interior of the focusing-ring and an exterior of the cathode and the mating threads extend for a distance of between 5 millimeters and 40 millimeters in a direction parallel to the longitudinal-axis.

Assignees

• Moxtek Inc

Inventors

• Peterson Dustin
• Zimmerman Richard
• Jones Vince
• Miller Eric

Classifications

• H01J2237/032

  Mounting or supporting · CPC title

• H01J2229/4831

  Electrode supports · CPC title

• H01J37/065

  Construction of guns or parts thereof (H01J37/067 - H01J37/077 take precedence) · CPC title

• H01J35/165

  joining connectors to the tube · CPC title

• H01J2237/083

  Beam forming · CPC title