Ion source apparatus and method

• US 7,122,966 B2
• Filed: 12/16/2004
• Issued: 10/17/2006
• Est. Priority Date: 12/16/2004
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Bergström, Jan-Olof, Norling, Jonas Ove
• Primary Examiner(s): Philogene, Haissa
• Application Number:
  US11/012,125
• Publication Number:
  US 20060132068A1
• Time in Patent Office: 670 Days
• Field of Search: 31511121-11141, 31511171-11191, 250/423.R, 250/427, 250/492.21, 313/231.31, 313/230, 313/62, 313/362.1, 313/363.1
• US Class Current: 315/111.81
• CPC Class Codes: H01J 27/08 using arc discharge
• CPC Class Codes: H05H 13/00 Magnetic resonance accelerators; Cyclotrons strophotrons, turbine tubes H01J25/62

Abstract

The invention relates to a method and apparatus that can improve the lifetime and performance of an ion source in a cyclotron. According to one embodiment, the invention comprises an ion source tube for sustaining a plasma discharge therein. The ion source tube comprises a slit opening along a side of the ion source tube, wherein the slit opening has a width less than 0.29 mm. The ion source tube also comprises an end opening in an end of the ion source tube. The end opening is smaller than an inner diameter of the ion source tube and is displaced by 0–1.5 mm from a central axis of the ion source tube toward the slit opening. The plasma column is displaced 0.2 to 0.5 mm relative the slit opening. The ion source tube comprises a cavity that accommodates the plasma discharge. The invention also relates to a method for making an ion source tube.

Claims

1. An ion source tube for sustaining a plasma discharge therein, the ion source tube comprising:

a slit opening along a side of the ion source tube, wherein the slit opening has a width less than 0.29 mm;

an end opening in an end of the ion source tube, wherein the end opening is smaller than an inner diameter of the ion source tube and is displaced by 0–

1.5 mm from a central axis of the ion source tube toward the slit opening; and

a cavity that accommodates the plasma discharge.

2. The ion source tube of claim 1, wherein the end opening has a diameter of 2.5–

5 mm.

3. The ion source tube of claim 1, wherein at least one of a built-in restrictor and the end opening causes an edge of the plasma discharge to be 0.2–

0.5 mm away from the slit opening.

4. The ion source tube of claim 1, wherein the plasma discharge has a diameter of 2.5–

5 mm.

5. The ion source tube of claim 1, wherein the slit opening has a width of greater than 0.1 mm.

6. The ion source tube of claim 1, wherein the slit opening has a width between 0.15 mm and 0.25 mm.

7. The ion source tube of claim 1, wherein the slit opening has a width of about 0.2 mm.

8. The ion source tube of claim 1, wherein the ion source tube has a one-piece construction.

9. The ion source tube of claim 8, further comprising a restrictor ring for insertion into the one-piece ion source tube to alter the geometry of the cavity.

10. The ion source tube of claim 1, wherein the ion source tube is biased as an anode for the plasma discharge.

11. The ion source tube of claim 1, wherein the ion source tube comprises one or more materials that are resistant to the plasma discharge.

12. The ion source tube of claim 1, wherein the ion source tube comprises copper and tungsten.

13. The ion source tube of claim 1, wherein the end opening is displaced by greater than zero millimeter from the central axis of the ion source tube toward the slit opening.

14. A method for making an ion source tube, the method comprising:

forming an ion source tube, the ion source tube comprising;

a slit opening along a side of the ion source tube, wherein the slit opening has a width of less than 0.29 mm;

an end opening in an end of the ion source tube, wherein the end opening is smaller than an inner diameter of the ion source tube and is displaced by 0–

1.5 mm from a central axis of the ion source tube toward the slit opening; and

a cavity in which the plasma discharge is located.

15. The method of claim 14, wherein the ion source tube is formed as one piece.

16. The method according to claim 15 further comprising inserting at least one restrictor ring into the one-piece ion source tube to alter the geometry of the cavity.

17. The method according to claim 15, further comprising biasing the one-piece ion source tube as an anode for the plasma discharge.

18. The method according to claim 14, further comprising forming the end opening to have a diameter of 2.5–

5 mm.

19. The method according to claim 14, wherein at least one of a built-in restrictor and the end opening causes an edge of the plasma discharge to be 0.2–

0.5 mm away from the slit opening.

20. The method according to claim 14, wherein the plasma discharge has a diameter of 2.5–

5 mm.

21. The method according to claim 14, further comprising forming the slit opening to have a width of greater than 0.1 mm.

22. The method according to claim 14, further comprising forming the slit opening to have a width between 0.15 mm and 0.25 mm.

23. The method according to claim 14, further comprising forming the slit opening to have a width of about 0.2 mm.

24. The method according to claim 14, wherein the end opening is displaced by greater than zero millimeter from the central axis of the ion source tube toward the slit opening.

25. A PET tracer production system, the system comprising:

a target comprising atoms of a first type;

an ion source adapted to produce one or more ions from a plasma discharge; and

a particle accelerator capable of accelerating the one or more ions and directing the one or more ions towards the target to change the atoms of the first type to atoms of a second type;

wherein the ion source comprises an ion source tube, the ion source tube comprising;

a slit opening along a side of the ion source tube, wherein the slit opening has a width less than 0.29 mm;

an end opening in an end of the ion source tube, wherein the end opening is smaller than an inner diameter of the ion source tube and is displaced by 0–

1.5 mm from a central axis of the ion source tube toward the slit opening; and

a cavity that accommodates the plasma discharge.

26. The PET tracer production system according to claim 25, wherein the atoms of the second type are isotopes of the atoms of the first type.

27. The PET tracer production system according to claim 25, wherein the particle accelerator is a cyclotron accelerator.

28. The PET tracer production system according to claim 25, wherein the end opening of the ion source tube has a diameter of 2.5–

5 mm.

29. The PET tracer production system according to claim 25, wherein at least one of a built-in restrictor and the end opening causes an edge of the plasma discharge to be 0.2–

0.5 mm away from the slit opening.

30. The PET tracer production system according to claim 25, wherein the plasma discharge has a diameter of 2.5–

5 mm.

31. The PET tracer production system according to claim 25, wherein the slit opening of the ion source tube has a width of greater than 0.1 mm.

32. The PET tracer production system according to claim 25, wherein the slit opening of the ion source tube has a width between 0.15 mm and 0.25 mm.

33. The PET tracer production system according to claim 25, wherein the slit opening of the ion source tube has a width of about 0.2 mm.

34. The PET tracer production system according to claim 25, wherein the ion source tube has a one-piece construction.

35. The PET tracer production system according to claim 34, wherein the one-piece ion source tube further comprises a restrictor ring for insertion into the ion source tube to alter the geometry of the cavity.

36. The PET tracer production system according to claim 25, wherein the ion source tube is biased as an anode for the plasma discharge.

37. The PET tracer production system according to claim 25, wherein the end opening of the ion source tube is displaced by greater than zero millimeter from the central axis of the ion source tube toward the slit opening.