Integral cathode
View Patent ↗An integral cathode for use with x-ray devices. The integral cathode includes an emitter made of a refractory metal such as tungsten, preferably doped with rhenium to afford malleability during construction and assembly. The integral cathode also includes a support cartridge, preferably composed of an electrically non-conductive material such as ceramic, in which the emitter is received. The support cartridge electrically isolates the cathode from the other components and structures of the x-ray device. Additionally, the support cartridge serves to impose, and maintain, a parabolic curve in the emitter. The parabolic form of the emitter naturally shapes an electron beam by causing electrons discharged from the emitter to converge at a focal spot. In this way, both the emission and focusing functions of the cathode are integrated and performed by a single part.
1. In an x-ray tube comprising a vacuum enclosure having disposed therein a target anode with a target surface, an integral cathode disposed in the vacuum enclosure and being spaced apart from the target surface of the target anode, the integral cathode comprising:
(a) an emitter configured to receive a flow of electrical current such that thermionic emission of electrons from the emitter is facilitated, said emitter having a predetermined geometrical configuration oriented to cause at least some emitted electrons to be directed at the target surface of the target anode and converge at a focal spot, wherein said predetermined geometrical configuration provides an emitter having a cross-section substantially in the shape of an arc so that a concave side of said emitter is directed towards the target surface of the anode, and the emitter including at least one cutout; and
(b) a support cartridge, said support cartridge providing structural support for said emitter.
2. The integral cathode as recited in claim 1 , wherein the emitter is substantially confined within the support cartridge.
3. The integral cathode as recited in claim 1 , wherein the arc shape of the emitter comprises one of: a substantially parabolic arc; and, a substantially circular arc.
4. The integral cathode as recited in claim 1 , wherein the emitter substantially comprises a single piece of material.
5. The integral cathode as recited in claim 1 , wherein the emitter substantially comprises a refractory metal.
6. The integral cathode as recited in claim 1 , wherein the emitter is doped with a dopant.
7. The integral cathode as recited in claim 1 , wherein the emitter comprises a plurality of subsidiary emitting portions.
8. The integral cathode as recited in claim 1 , wherein the support cartridge serves to substantially maintain the emitter in the arc shape.
9. The integral cathode as recited in claim 1 , wherein the support cartridge substantially comprises one of: a ceramic material; and, cataphoretically coated iron.
10. The integral cathode as recited in claim 1 , wherein the support cartridge comprises:
an electrically conductive portion; and
a non-electrically conductive portion.
11. An integral cathode, comprising:
an emitter substantially comprising an emissive surface having a shape configured to direct a majority of electrons emitted from spatially diverse locations on the emissive surface to a common focal point, the emitter being configured to receive a flow of electrical current such that thermionic emission of electrons from the emitter is facilitated, wherein the emitter includes at least one cutout; and
a support cartridge within which the emitter is at least partially received.
12. The integral cathode as recited in claim 11 , wherein the emissive surface substantially comprises a single piece of material.
13. The integral cathode as recited in claim 11 , wherein the emitter is substantially confined within the support cartridge.
14. The integral cathode as recited in claim 11 , wherein the emissive surface is substantially concave in shape.
15. The integral cathode as recited in claim 14 , wherein the substantially concave shape comprises one of: a substantially parabolic arc; and, a substantially circular arc.
16. The integral cathode as recited in claim 11 , wherein the emitter substantially comprises a refractory metal.
17. The integral cathode as recited in claim 11 , wherein the emitter is doped with a dopant.
18. The integral cathode as recited in claim 11 , wherein the support cartridge serves to substantially maintain the emitter in the shape.
19. The integral cathode as recited in claim 11 , wherein the support cartridge substantially comprises one of: a ceramic material; and, cataphoretically coated iron.
20. The integral cathode as recited in claim 11 , wherein the support cartridge comprises at least one of:
an electrically conductive portion; and
a non-electrically conductive portion.
21. An integral cathode, comprising:
an emitter substantially comprising a substantially concave emissive surface configured to be oriented toward a target surface of a target anode, and the emitter including at least one cutout; and
a support cartridge within which the emitter is at least partially received.
22. The integral cathode as recited in claim 21 , wherein the substantially concave shape comprises one of: a substantially parabolic arc; and, a substantially circular arc.
23. The integral cathode as recited in claim 21 , wherein the emissive surface substantially comprises a single piece of material.
24. The integral cathode as recited in claim 21 , wherein the emitter substantially comprises a refractory metal.
25. The integral cathode as recited in claim 21 , wherein the support cartridge comprises:
an electrically conductive portion; and
a non-electrically conductive portion.
26. An x-ray device, comprising:
a vacuum enclosure;
a target anode having a target surface and being substantially disposed within the vacuum enclosure such that the target anode and target surface are spaced apart from the vacuum enclosure; and
an integral cathode substantially disposed within the vacuum enclosure and comprising:
an emitter substantially comprising an emissive surface having a shape configured to direct a majority of electrons emitted from spatially diverse locations on the emissive surface to a common focal point proximate the target surface, wherein the emitter includes at least one cutout; and
a support cartridge within which the emitter is at least partially received.
27. The x-ray device as recited in claim 26 , wherein the emitter is configured to receive a flow of electrical current such that thermionic emission of electrons from the emitter is facilitated.
28. The x-ray device as recited in claim 26 , wherein the emissive surface of the emitter substantially comprises a single piece of material.
29. The x-ray device as recited in claim 26 , wherein the emissive surface is substantially concave in shape.
30. The x-ray device as recited in claim 29 , wherein the substantially concave shape comprises one of: a substantially parabolic arc; and, a substantially circular arc.
31. The x-ray device as recited in claim 26 , wherein the emitter substantially comprises a refractory metal.
32. The x-ray device as recited in claim 26 , wherein the emitter is doped with a dopant.
33. The x-ray device as recited in claim 26 , wherein the support cartridge substantially comprises one of: a ceramic material; and, cataphoretically coated iron.
34. The x-ray device as recited in claim 26 , wherein the support cartridge comprises at least one of:
an electrically conductive portion; and
a non-electrically conductive portion.
35. The x-ray device as recited in claim 26 , wherein the support cartridge facilitates maintenance of the emitter in a predetermined shape.