Small x-ray tube with electron beam control optics

• US 8,761,344 B2
• Filed: 12/29/2011
• Issued: 06/24/2014
• Est. Priority Date: 12/29/2011
• Status: Expired due to Fees

• Current Assignee: Moxtek Inc (Nippon Kayaku Company Limited)
• Original Assignee: Moxtek Inc (Nippon Kayaku Company Limited)
• Inventors: Reynolds, David, Miller, Eric J., Cornaby, Sterling W., Hullinger, Derek, Jensen, Charles R.
• Primary Examiner(s): Midkiff, Anastasia
• Application Number:
  US13/340,067
• Publication Number:
  US 20130170623A1
• Time in Patent Office: 908 Days
• Field of Search: 378/119, 378/121, 378/136, 378/138
• US Class Current: 378/138
• CPC Class Codes: H01J 2235/086 Target geometry
• CPC Class Codes: H01J 35/066 Details of electron optical components, e.g. cathode cups
• CPC Class Codes: H01J 35/153 Spot position control
• CPC Class Codes: H01J 35/16 Vessels; Containers; Shields associated therewith

Abstract

An x-ray tube comprising an anode and a cathode disposed at opposing ends of an electrically insulative cylinder. The x-ray tube includes an operating range of 15 kilovolts to 40 kilovolts between the cathode and the anode. The x-ray tube has an overall diameter, defined as a largest diameter of the x-ray tube anode, cathode, and insulative cylinder, of less than 0.6 inches. A direct line of sight exists between all points on an electron emitter at the cathode to a target at the anode.

Claims

1. An x-ray tube, comprising:

a. an electrically insulative cylinder;

b. an anode disposed at one end of the insulative cylinder, the anode including a target which is configured to emit x-rays in response to electrons impinging upon the target;

c. a cathode disposed at an opposing end of the insulative cylinder from the anode, the cathode including an electron emitter;

d. a primary optic, comprising a cavity in the cathode, having an open end facing the electron emitter, and disposed on an opposite side of the electron emitter from the anode;

e. an operating range of 15 kilovolts to 40 kilovolts between the cathode and the anode;

f. an overall diameter, defined as a largest diameter of the x-ray tube anode, cathode, and insulative cylinder, being less than 0.6 inches;

g. a cylindrical, electrically conductive electron optic divergent lens, attached to the anode and electrically connected to the anode, and having a far end extending from the anode towards the cathode;

h. a cylindrical, electrically conductive electron optic convergent lens, attached to and surrounding the cathode and electrically connected to the cathode, and having a far end extending from the cathode towards the anode;

i. an electron flight distance, from the electron emitter to the target, of less than 0.8 inches;

j. a maximum voltage standoff length, from the far end of the divergent lens to the far end of the convergent lens, being less than 0.25 inches;

k. an insulative cylinder length from closest contact with the cathode to closest contact with the anode being less than 0.7 inches; and

l. a direct line of sight between all points on the electron emitter through a central portion of the convergent lens, through a central portion of the divergent lens, to the target.

2. The x-ray tube of claim 1, wherein an inside diameter of the convergent lens is greater than 0.95 times an outside diameter of the divergent lens.

3. The x-ray tube of claim 1, wherein the electron flight distance, from the electron emitter to the target, is less than 0.7 inches.

4. The x-ray tube of claim 1, wherein the electron flight distance divided by the overall diameter is greater than 1.1 and less than 1.4.

5. The x-ray tube of claim 1, wherein an outside diameter of the convergent lens divided by the maximum voltage standoff length is greater than 1 and less than 2.

6. The x-ray tube of claim 1, wherein the target is a transmission target.

7. The x-ray tube of claim 1, wherein an overall length, of the x-ray tube from a far end of the cathode to a far end of the anode, is less than 1.1 inches.

8. The x-ray tube of claim 1, wherein the operating range is from 15 kilovolts to 60 kilovolts.

9. The x-ray tube of claim 1, wherein an outside diameter of the divergent lens divided by an inside diameter of the divergent lens is greater than 1.9 and less than 3.0.

10. An x-ray tube, comprising:

a. an electrically insulative cylinder;

b. an anode disposed at one end of the insulative cylinder, the anode including a target which is configured to emit x-rays in response to electrons impinging upon the target;

c. a cathode disposed at an opposing end of the insulative cylinder from the anode, the cathode including an electron emitter;

d. a primary optic, comprising a cavity in the cathode, having an open end facing the electron emitter, and disposed on an opposite side of the electron emitter from the anode;

e. an operating range of 15 kilovolts to 40 kilovolts between the cathode and the anode;

f. an overall diameter, defined as a largest diameter of the x-ray tube anode, cathode, and insulative cylinder, being less than 0.6 inches;

g. a cylindrical, electrically conductive electron optic convergent lens, attached to and surrounding the cathode and electrically connected to the cathode, and having a far end extending from the cathode towards the anode;

h. an electron flight distance, from the electron emitter to the target, of less than 0.7 inches;

i. a maximum voltage standoff length, from the far end of the divergent lens to the far end of the convergent lens, being less than 0.25 inches;

j. a direct line of sight between all points on the electron emitter through a central portion of the convergent lens to the target; and

k. wherein 90% of electrons emitted by the electron emitter are absorbed within a 0.75 millimeter radius of a center of the target.

11. The x-ray tube of claim 10, wherein the target is a transmission target.

12. The x-ray tube of claim 10, wherein the operating range is from 15 kilovolts to 60 kilovolts.

13. The x-ray tube of claim 10, wherein 90% of electrons emitted by the electron emitter are absorbed within a 0.4 millimeter radius of a center of the target.

14. The x-ray tube of claim 10, wherein 90% of electrons emitted by the electron emitter are absorbed within a 0.3 millimeter diameter spot on the target.

15. An x-ray tube, comprising:

a. an electrically insulative cylinder;

b. an anode disposed at one end of the insulative cylinder, the anode including a target which is configured to emit x-rays in response to electrons impinging upon the target;

c. a cathode disposed at an opposing end of the insulative cylinder from the anode, the cathode including an electron emitter;

d. an operating range of 15 kilovolts to 40 kilovolts between the cathode and the anode;

e. an insulative cylinder length from closest contact with the cathode to closest contact with the anode being less than 0.7 inches;

f. an overall diameter, defined as a largest diameter of the x-ray tube anode, cathode, and insulative cylinder, being less than 0.6 inches;

g. a direct line of sight between all points on the electron emitter to the target; and

h. wherein 90% of electrons emitted by the electron emitter are absorbed within a 0.75 millimeter radius of a center of the target.

16. The x-ray tube of claim 15, wherein the target is a transmission target.

17. The x-ray tube of claim 15, wherein the operating range is from 15 kilovolts to 60 kilovolts.

18. The x-ray tube of claim 15, wherein 90% of electrons emitted by the electron emitter are absorbed within a 0.4 millimeter radius of a center of the target.

19. The x-ray tube of claim 15, wherein 90% of electrons emitted by the electron emitter are absorbed within a 0.3 millimeter diameter spot on the target.

20. The x-ray tube of claim 15, wherein the x-ray tube has an electron flight distance, from the electron emitter to the target, of less than 0.7 inches.