Magnetron with diamond coated cathode

• US 6,686,696 B2
• Filed: 03/08/2001
• Issued: 02/03/2004
• Est. Priority Date: 03/08/2001
• Status: Expired due to Term

• Current Assignee: Teraphysics Corporation (Genvac Holdings Ltd.)
• Original Assignee: Genvac Aerospace Corporation
• Inventors: Takacs, Laszlo A., Mearini, Gerald T.
• Primary Examiner(s): Lee, Benny T.
• Application Number:
  US09/802,585
• Publication Number:
  US 20020125827A1
• Time in Patent Office: 1,062 Days
• Field of Search: 315/39.51, 315/39.63, 315/39.67, 315/39.71, 313/103.R, 313/309, 313/326, 313/351
• US Class Current: 315/39.63
• CPC Class Codes: H01J 2201/30457 Diamond
• CPC Class Codes: H01J 2201/32 Secondary emission electrodes
• CPC Class Codes: H01J 23/05 having a cylindrical emissive surface, e.g. cathodes for magnetrons

Abstract

A radio frequency magnetron device for generating radio frequency power includes a cathode at least partially formed from a diamond material. An anode is disposed concentrically around the cathode. An electron field is provided radially between the anode and the cathode. First and second oppositely charged pole pieces are operatively connected to the cathode for producing a magnetic field in a direction perpendicular to the electric field. A filament is provided within the electron tube which when heated produces primary electrons. Alternatively, a voltage is applied to the anode which causes primary electrons to emit from the diamond coated cathode. A portion of the primary electrons travel in a circular path and induce radio frequency power. Another portion of the primary electrons spiral back and collide with the cathode causing the emission of secondary electrons. The secondary electron emission sustains operation of the magnetron device once the device has been started.

Claims

1. A radio frequency (RE) magnetron device for generating microwave power comprising:

a cathode either partially or entirely comprised of a diamond material, the diamond material configured to emit electrons and sustain operation of the magnetron device via secondary electron emission and without assistance of a heating source, the cathode having a generally smooth surface;

an anode disposed concentrically around the cathode, an electric field provided radially between the anode and the cathode; and

first and second oppositely charged pole pieces operatively connected to the cathode for producing a magnetic field in a direction perpendicular to the electric field.

2. The magnetron device according to claim 1, wherein the cathode is formed entirely from a diamond material.

3. The magnetron device according to claim 1, wherein the cathode is comprised of a carbide growth facilitating material coated with the diamond material.

4. The magnetron device according to claim 1, further comprising a plurality of walls extending from the anode, the plurality of walls sectioning an annular recess defined by the anode and the cathode into a plurality of cavities.

5. The magnetron device according to claim 1, further comprising a thermionic emission source for initiating electron emission within the magnetron device, said thermionic emission source being deactivated after initiation of electron emission, and operation of the magnetron being sustained without assistance of the thermionic emission source.

6. The magnetron device according to claim 5, wherein the thermionic emission source comprises a filament which is heated, thereby causing electrons to emit from the filament.

7. The magnetron device according to claim 1, wherein the diamond material is a chemical vapor deposited material.

8. The magnetron device according to claim 1, wherein the diamond material is doped with at least one of a cesium source and a boron source for enhancing the secondary electron emission of the magnetron device.

9. A secondary electron emitting device for a magnetron comprising:

a cathode either partially or entirely comprised of a diamond material, the diamond material configured to emit electrons and sustain operation of the magnetron via secondary electron emission without assistance of a heating source; and

an anode in spaced relation with the cathode.

10. The secondary electron emitting device as set forth in claim 9, wherein the diamond material has a secondary electron coefficient greater than 50.

11. The secondary electron emitting device according to claim 9, wherein an electric field is provided between the cathode and the anode.

12. The secondary electron emitting device according to claim 11, further comprising first and second oppositely polarized magnets operatively connected to the cathode for producing a magnetic field in a direction perpendicular to the electric field.

13. The secondary electron emitting device according to claim 10, wherein the cathode is formed entirely from a diamond material.

14. The secondary electron emitting device according to claim 9, wherein the cathode is comprised of a carbide growth facilitating material coated with the diamond material.

15. The secondary electron emitting device according to claim 9, further comprising a plurality of walls extending from the anode, the plurality of walls sectioning an annular space defined by the anode and the cathode into a plurality of cavities.

16. The secondary electron emitting device according to claim 9, further comprising a thermionic emission source for initiating electron emission, said thermionic emission source being deactivated after initiation of electron emission, secondary electron emission being sustained without assistance of the thermionic emission source.

17. The secondary electron emitting device according to claim 16, wherein the thermionic emission source comprises a filament which is heated, thereby causing electrons to emit from the filament.

18. The magnetron device according to claim 9, wherein the diamond material is a chemical vapor deposited material.

19. The secondary electron emitting device according to claim 9, wherein the diamond material is doped with a cesium source for enhancing the secondary electron emission of the magnetron device.

20. A method for producing radio frequency power using a magnetron device comprising the steps of:

coating a substantially cylindrical cathode with a diamond material;

placing an anode in a spaced relationship with the diamond coated cathode;

applying an electric field between the anode and the cathode;

emitting primary electrons from the cathode for initiating operation of the magnetron device; and

emitting secondary electrons from the cathode for sustaining operation of the magnetron device, the emitting of secondary electrons responsive to the emitting of the primary electrons.

21. The method according to claim 20, wherein the step of emitting secondary electrons further includes colliding a portion of the primary electrons with the cathode thereby producing the secondary electrons.

22. The method according to claim 20, wherein the step of emitting primary electrons further includes heating a filament in order to thermionically generate the primary electrons.

23. The method according to claim 20, wherein the step of emitting primary electrons includes applying a voltage to the diamond material to cause primary electrons to emit from the cathode by field emission.