Cathode header optic for x-ray tube

• US 20090022277A1
• Filed: 07/18/2007
• Published: 01/22/2009
• Est. Priority Date: 07/18/2007
• Status: Active Grant

• Current Assignee: Moxtek (Polatechno Co.,Ltd.)
• Original Assignee: Moxtek (Polatechno Co.,Ltd.)
• Inventors: Bard, Erik C., Liddiard, Steven D., Jensen, Charles R.
• Granted Patent: US 7,529,345 B2
• Time in Patent Office: Days
• US Class Current: 378/138
• CPC Class Codes: H01J 35/066 Details of electron optical components, e.g. cathode cups
• CPC Class Codes: H01J 35/147 Spot size control

Abstract

A cathode header optic for an x-ray tube includes an elongate trench with opposite trench walls. A cup recess is formed in the trench between the opposite trench walls, and has a bounded perimeter. A cathode element is disposed in the trench at the cup recess. The cathode element is capable of heating and releasing electrons. A secondary cathode optic defining a cathode ring can be disposed about the header optic. The cathode optics can form part of an x-ray tube.

Claims

1. A cathode header optic device for an x-ray tube, the device comprising:

an elongate trench with opposite trench walls and a bottom wall;

a cup recess formed in the trench and with an opening thereto formed in the bottom wall of the trench, and having a bounded perimeter including a bottom; and

a cathode element disposed in the trench at the opening of the cup recess, the cathode element capable of heating and releasing electrons.

2. A device in accordance with claim 1, wherein the trench is substantially rectangular and the cup recess is substantially cylindrical.

4. A device in accordance with claim 1, further comprising:

a lead bore adjacent the cup recess; and

a lead pin extending through the lead bore and electrically coupled to the cathode element.

5. A device in accordance with claim 4, wherein the cup recess and the lead bore each have an outer perimeter substantially on the same plane, and wherein the cup recess and lead bore overlap forming a passage;

and wherein the lead pin is disposed adjacent the passage and substantially spans the passage.

6. A device in accordance with claim 4, wherein an end of the cathode element is electrically connected directly to the header optic.

7. A device in accordance with claim 1, wherein the cathode element is disposed between a bottom wall of the cup recess and a top of the trench.

8. A device in accordance with claim 1, wherein the cathode has a diameter less than 1 inch;

and wherein the trench and the cup recess form an electron optic and shape an electric field and an electron beam with a spot size less than the cathode element.

9. A device in accordance with claim 1, wherein the trench has inclined side walls.

10. A device in accordance with claim 1, wherein the cup recess includes a concave bottom.

11. A device in accordance with claim 1, further comprising:

a cathode ring disposed in front of the cup recess and defining a secondary cathode optic, the cathode ring having a bore extending to the trench.

28. A device in accordance with claim 1, wherein a long diameter of the cup recess is less than a long dimension of the trench.

29. A device in accordance with claim 1, wherein a long diameter of the cup recess is greater than a long dimension of a coil portion of the cathode element.

30. A device in accordance with claim 1, wherein a long diameter of the cup recess is less than a long dimension of the cathode element.

31. A device in accordance with claim 1, further comprising:

a lead bore formed outside of the trench; and

a lead pin extending through the lead bore and electrically coupled to the cathode element.

3. (canceled)

12. An x-ray tube device, comprising:

a) an evacuated dielectric tube;

b) an anode, disposed at an end of the tube, including a material configured to produce x-rays in response to impact of electrons;

c) a cathode, disposed at an opposite end of the tube opposing the anode, including a cathode element configured to produce electrons accelerated towards the anode in response to an electric field between the anode and the cathode; and

d) the cathode including a cathode header optic comprising;

i) an elongate trench with opposite trench walls and a bottom wall;

ii) a cup recess formed in the trench and with an opening thereto formed in the bottom wall of the trench, and having a bounded perimeter including a bottom; and

iii) the cathode element disposed in the trench at the opening of the cup recess.

13. A device in accordance with claim 12, wherein the trench is substantially rectangular and the cup recess is substantially cylindrical.

15. A device in accordance with claim 12, further comprising:

a lead bore adjacent the cup recess; and

a lead pin extending through the lead bore and electrically coupled to the cathode element.

16. A device in accordance with claim 15, wherein the cup recess and the lead bore each have an outer perimeter substantially on the same plane, and wherein the cup recess and lead bore overlap forming a passage;

and wherein the lead pin is disposed adjacent the passage and substantially spans the passage.

17. A device in accordance with claim 12, wherein the cathode element is disposed between a bottom wall of the cup recess and a top of the trench.

19. A device in accordance with claim 12, wherein the tube has a length less than 3 inches and a diameter less than 1 inch;

wherein a weight of the tube, the cathode, the anode, and associated high-voltage insulation and radiation shielding is less than approximately 1 pound; and

wherein the trench and the cup recess form an electron optic and shape an electric field and an electron beam with a spot size less than the cathode element.

20. A device in accordance with claim 12, wherein the trench has inclined side walls.

21. A device in accordance with claim 12, wherein the cup recess includes a concave bottom.

22. A device in accordance with claim 12, further comprising:

a cathode ring disposed between the cathode header optic and the tube and defining a secondary cathode optic, the cathode ring having a bore extending to the trench.

14. (canceled)

18. (canceled)

23. An x-ray tube device, comprising:

a) an evacuated dielectric tube;

b) an anode, disposed at an end of the tube, including a material configured to produce x-rays in response to impact of electrons;

c) a cathode, disposed at an opposite end of the tube opposing the anode, including a cathode element configured to produce electrons accelerated towards the anode in response to an electric field between the anode and the cathode; and

d) the cathode including a header optic comprising;

i) an elongate trench with opposite trench walls and a bottom wall;

ii) a cup recess formed in the trench and with an opening thereto formed in the bottom wall of the trench, and having a bounded perimeter including a bottom;

iii) the cathode element disposed in the trench at the opening of the cup recess;

iv) a lead bore adjacent the cup recess; and

v) a lead pin extending through the lead bore and electrically coupled to the cathode element.

24. A device in accordance with claim 23, wherein the cup recess and the lead bore each have an outer perimeter substantially on the same plane, and wherein the cup recess and lead bore overlap forming a passage;

and wherein the lead pin is disposed adjacent the passage and substantially spans the passage.

25. A device in accordance with claim 23, wherein the trench is substantially rectangular;

and wherein the cup recess is substantially circular.

26. An x-ray tube device, comprising:

a) an evacuated dielectric tube;

b) an anode, disposed at an end of the tube, including a material configured to produce x-rays in response to impact of electrons;

c) a cathode, disposed at an opposite end of the tube opposing the anode;

d) a cathode element configured to produce electrons accelerated towards the anode in response to an electric field between the anode and the cathode;

e) the cathode including a header comprising;

i) a single lead bore extending through the header; and

ii) a single lead pin extending through the lead bore and electrically coupled to an end of the cathode element, another end of the cathode element being directly electrically coupled to the header.

27. An x-ray tube device, comprising:

a) an evacuated dielectric tube;

b) an anode, disposed at an end of the tube, including a material configured to produce x-rays in response to impact of electrons;

c) a cathode, disposed at an opposite end of the tube opposing the anode, including a cathode element configured to produce electrons accelerated towards the anode in response to an electric field between the anode and the cathode;

d) the cathode including a cathode header optic comprising;

i) an elongate trench with opposite trench walls and a bottom wall;

ii) a cup recess formed in the trench and with an opening thereto formed in the bottom wall of the trench, and having a bounded perimeter including a bottom; and

iii) the cathode element disposed in the trench at the opening of the cup recess; and

e) the cathode further including a secondary cathode optic comprising;

i) a cathode ring disposed between the cathode header optic and the tube and having a perimeter wall defining a well with the trench disposed at a bottom of the well.