Inductively-driven plasma light source

• US 7,307,375 B2
• Filed: 07/09/2004
• Issued: 12/11/2007
• Est. Priority Date: 07/09/2004
• Status: Active Grant

• Current Assignee: Hamamatsu Photonics KK
• Original Assignee: Energetiq Technology Incorporated (Hamamatsu Photonics KK)
• Inventors: Smith, Donald K., Besen, Matthew M., Horne, Stephen F., Blackborow, Paul A.
• Primary Examiner(s): WILLIAMS, JOSEPH L
• Application Number:
  US10/888,795
• Publication Number:
  US 20060006775A1
• Time in Patent Office: 1,250 Days
• Field of Search: 378/119, 313/31, 315/248
• US Class Current: 313/31
• CPC Class Codes: H01J 65/048 the field being produced by using an excitation coil
• CPC Class Codes: H05G 2/003 being produced from a liquid or gas

Abstract

An apparatus for producing light includes a chamber that has a plasma discharge region and that contains an ionizable medium. The apparatus also includes a magnetic core that surrounds a portion of the plasma discharge region. The apparatus also includes a pulse power system for providing at least one pulse of energy to the magnetic core for delivering power to a plasma formed in the plasma discharge region. The plasma has a localized high intensity zone.

Claims

1. A light source comprising:

a chamber having a plasma discharge region and containing an ionizable medium;

a magnetic core that surrounds a portion of the plasma discharge region; and

a pulse power system for providing at least one pulse of energy to the magnetic core for delivering power to a plasma formed in the plasma discharge region that forms the secondary of a transformer according to Faraday'"'"'s law of induction, wherein the plasma has a localized high intensity zone.

2. The light source of claim 1 wherein the plasma substantially varies in current density along a path of current flow in the plasma.

3. The light source of claim 1 wherein the zone is a point source of high intensity light.

4. The light source of claim 1 wherein the zone is a region where the plasma is pinched to form a neck.

5. The light source of claim 1 wherein a feature in the chamber creates the zone.

6. The light source of claim 5 wherein the feature is configured to substantially localize an emission of light by the plasma.

7. The light source of claim 5 wherein the feature is located remotely relative to the magnetic core.

8. The light source of claim 5 wherein the feature defines a necked region for localizing an emission of light by the plasma.

9. The light source of claim 5 wherein the feature comprises a gas inlet.

10. The light source of claim 5 wherein the feature comprises cooling capability.

11. The light source of claim 10 wherein the cooling capability involves pressurized subcooled flow boiling of water.

12. The light source of claim 5 wherein the feature is at least one aperture in a rotating disk.

13. The light source of claim 12 wherein a thin gas layer conducts heat from the disk to a cooled surface.

14. The light source of claim 1 wherein gas pressure creates the zone.

15. The light source of claim 1 wherein current flow in the plasma creates the zone.

16. The light source of claim 1 wherein the at least one pulse of energy provided to the magnetic core forms the plasma.

17. The light source of claim 1 wherein the pulse power system provides each pulse of energy at a frequency of between about 100 pulses per second and about 15,000 pulses per second.

18. The light source of claim 1 wherein each pulse of energy is provided for a duration of time between about 10 ns and about 10 μ

s.

19. The light source of claim 1 wherein the pulse power system comprises an energy storage device.

20. The light source of claim 19 wherein the energy storage device comprises at least one capacitor.

21. The light source of claim 1 wherein the pulse power system comprises a magnetic pulse-compression generator.

22. The light source of claim 1 wherein the pulse power system comprises a magnetic switch for selectively delivering each pulse of energy to the magnetic core.

23. The light source of claim 1 wherein the pulse power system comprises a saturable inductor.

24. The light source of claim 1 wherein the magnetic core is configured to produce at least essentially a Z-pinch in a channel region located in the chamber.

25. The light source of claim 1 wherein the magnetic core is configured to produce at least essentially a capillary discharge in a channel region located in the chamber.

26. The light source of claim 1 further comprising at least one port for introducing the ionizable medium into the chamber.

27. The light source of claim 1 wherein the ionizable medium is at least one or more gases selected from the group consisting of Xenon, Lithium, Tin, Nitrogen, Argon, Helium, Fluorine, Ammonia, Stannane, Krypton and Neon.

28. The light source of claim 1 comprising an ionization source for pre-ionizing the ionizable medium.

29. The light source of claim 28 wherein the ionization source is a source selected from the group consisting of an ultraviolet lamp, an RF source, a spark plug and a DC discharge source.

30. The light source of claim 1 comprising an enclosure that at least partially encloses the magnetic core.

31. The light source of claim 30 wherein the enclosure defines a plurality of holes.

32. The light source of claim 31 wherein a plurality of plasma loops pass through the plurality of holes when the magnetic core delivers power to the plasma.

33. The light source of claim 31 wherein the enclosure comprises two parallel plates.

34. The light source of claim 33 wherein the parallel plates are conductive and form a primary winding around the core.

35. The light source of claim 30 wherein coolant flows through the enclosure for cooling a location adjacent the localized high intensity zone.

36. The light source of claim 30 wherein the enclosure comprises a material selected from the group consisting of copper, tungsten, aluminum and copper-tungsten alloys.

37. The light source of claim 1 wherein the plasma is a plasma loop that forms the secondary of a transformer according to Faraday'"'"'s law of induction.

38. The light source of claim 37 wherein the plasma loop surrounds the magnetic core.

39. The light source of claim 1 wherein the light source is configured to produce light at wavelengths shorter than about 100 nm when the light source generates a plasma discharge.

40. The light source of claim 1 comprising two parallel conductive plates that form the conductive path around the magnetic core and the primary winding of the transformer.

41. The light source of claim 40 comprising a metal strip that forms the conductive path around the magnetic core and the primary winding of the transformer.

42. The light source of claim 1 wherein the power delivered to the plasma is based on a magnetic field produced by the magnetic core and frequency and duration of the pulses of energy delivered to the transformer.

43. A light source comprising:

a chamber having a plasma discharge region and containing an ionizable medium;

a transformer comprising a first magnetic core that surrounds a portion of the plasma discharge region;

a second magnetic core linked with the first magnetic core by a current; and

a power supply for providing a first signal to the second magnetic core, wherein the second magnetic core provides a second signal to the first magnetic core when the second magnetic core saturates, and wherein the first magnetic core delivers power to a plasma formed in the plasma discharge region from the ionizable medium in response to the second signal and wherein the plasma forms the secondary of a transformer according to Faraday'"'"'s law of induction.

44. The light source of claim 43 comprising two parallel plates forming a primary winding around the first magnetic core and conducting the current which links the first and second magnetic cores.

45. The light source of claim 43 wherein inductive leakage current flowing from the second magnetic core to the magnetic core surrounding the portion of the plasma discharge region pre-ionizes the ionizable medium.

46. A light source comprising:

a chamber having a channel region and containing an ionizable medium;

a magnetic core that surrounds a portion of the channel region; and

a pulse power system for providing at least one pulse of energy to the magnetic core for exciting the ionizable medium to form at least essentially a Z-pinch in a plasma in the channel region that forms the secondary of a transformer according to Faraday'"'"'s law of induction.

47. The light source of claim 46, wherein the current density of the plasma is greater than about 1 KS/cm².

48. The light source of claim 46, wherein pressure in the channel region is less than about 100 mTorr.

49. A light source comprising:

a chamber containing a light emitting plasma with a localized high intensity zone that emits a substantial portion of the emitted light;

a magnetic core that surrounds a portion of the light emitting plasma; and

a pulse power system for providing at least one pulse of energy to the magnetic core for delivering power to the plasma that forms the secondary of a transformer according to Faraday'"'"'s law of induction.

50. A light source comprising:

a chamber having a plasma discharge region and containing an ionizable medium;

a magnetic core that surrounds a portion of the plasma discharge region; and

a means for providing at least one pulse of energy to the magnetic core for delivering power to a plasma formed in the plasma discharge region that forms the secondary of a transformer according to Faraday'"'"'s law of induction, wherein the plasma has a localized high intensity zone.

51. A plasma source comprising:

a chamber having a plasma discharge region and containing an ionizable medium;

a magnetic core that surrounds a portion of the plasma discharge region and induces an electric current in the plasma sufficient to form a Z-pinch, wherein the plasma forms the secondary of a transformer.