Claims
- 1. An x-ray generating device comprising:
a chamber; a field emission cathode, the cathode comprising a nanostructure-containing material having an emitted electron current density of more than 4 A/cm2; an anode target; and an accelerating field established by an applied potential between the cathode and anode.
- 2. The device of claim 1, wherein the emitted current density is greater than 10,000 mA/cm2.
- 3. The device of claim 1, wherein an applied electrical field of 2-7 V/μm produces a stable current density of about 100 mA/cm2.
- 4. The device of claim 1, wherein the nanostructure-containing material comprises carbon nanotubes.
- 5. The device of claim 1, wherein the nanostructure-containing material comprises single-walled carbon nanotubes.
- 6. The device of claim 1, wherein the cathode comprises a substrate material at least partially covered with the nanostructure-containing material.
- 7. The device of claim 6, wherein the nanostructure-containing material is free of binder materials.
- 8. The device of claim 6, further comprising a metal interlayer between the substrate and the nanostructure-containing material.
- 9. The device of claim 6, further comprising a gate electrode.
- 10. The device of claim 6, wherein the nanostructure-containing material comprises a thin paper which is adhered to the substrate.
- 11. The device of claim 9, wherein the nanostructure-containing material comprises a patterned film defined by electron emitting materials aligned with openings disposed in the gate electrode.
- 12. The device of claim 9, further comprising a feedback circuit constructed to vary the applied potential between the gate electrode and the cathode thereby improving stability of the generated x-rays.
- 13. The device of claim 9, further comprising a focusing ring located above the gate electrode.
- 14. The device of claim 1, wherein the applied potential between the cathode and gate electrode is pulsed between on and off and produces a beam of field-emitted electrons during the period of the pulse being on and does not produce a beam of field-emitted electrons during the period of the pulse being off.
- 15. The device of claim 1, wherein the anode further comprises a plurality of target materials.
- 16. The device of claim 15, wherein the device is capable of selectively producing x-rays of different energies.
- 17. The device of claim 16, wherein a portion of the anode target comprises a first target material and another portion of the anode target comprises a second target material.
- 18. The device of claim 17, wherein the anode target comprises a conical face.
- 19. The device of claim 1, wherein the anode target comprises a focus spot 10-30 mm in length and 0.1-0.5 mm in width.
- 20. The device of claim 1, wherein the anode target comprises a target angle of 2°-10°.
- 21. The device of claim 1, wherein the device produces an apparent focal spot having an area of 0.1-0.5 mm2.
- 22. The device of claim 1, wherein the anode target comprises a focus spot 10-30 mm in length and 0.1-0.5 mm in width, and a target angle of 2°-10°, the device producing an apparent focus spot having an area of 0.1-0.5 mm2.
- 23. A method for producing x-rays comprising:
providing a chamber; introducing a field emission cathode into the chamber, the cathode comprising of a nanostructure-containing material having an emitted electron current density of more than 4 A/cm2; applying a control voltage to the cathode thereby causing a stream of electrons to be emitted; and providing an anode target within the chamber incident to the stream of emitted electrons thereby causing x-rays to be emitted from the anode target.
- 24. The method of claim 23, further comprising pulsing the incident electron beam.
- 25. The method of claim 24, wherein the pulsing of the incident beam is caused by the application and removal of the electric field on the field emission cathode.
- 26. The method of claim 23, wherein the nanostructure containing materials comprises single walled carbon nanotubes.
- 27. The method of claim 23, wherein the cathode comprises a substrate at least partially covered with the nanostructure-containing material.
- 28. The method of claim 23, further comprising providing the anode target with a portion comprising a first target material and with another portion comprising a second target material, and causing a first stream of electrons to strike the first target material and a second stream of electrons to strike the second target material, thereby causing the device to generate x-rays of different energies by applying the same control voltage.
- 29. The method of claim 23, further comprising processing the anode target with a focus spot 10-30 mm in length, 0.1-0.5 mm in width, and a target angle of 2°-10° thereby producing an apparent focus spot having an area of 0.1-0.5 m2.
- 30. The method of claim 23, wherein the amount of applied voltage is utilized to generate an x-ray beam of predetermined density and distribution.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0001] At least some aspects of this invention were made with Government support under the sponsorship of the Office of Naval Research, contract no. N00014-98-1-0597. The Government may have certain rights in this invention.
Continuations (1)
|
Number |
Date |
Country |
Parent |
09679303 |
Oct 2000 |
US |
Child |
10309126 |
Dec 2002 |
US |