Method of operating and process for fabricating an electron source
View Patent ↗A method of operating and process for fabricating an electron source. A conductive rod is covered by an insulating layer, by dipping the rod in an insulation solution, for example. The rod is then covered by a field emitter material to form a layered conductive rod. The rod may also be covered by a second insulating material. Next, the materials are removed from the end of the rod and the insulating layers are recessed with respect to the field emitter layer so that a gap is present between the field emitter layer and the rod. The layered rod may be operated as an electron source within a vacuum tube by applying a positive bias to the rod with respect to the field emitter material and applying a higher positive bias to an anode opposite the rod in the tube. Electrons will accelerate to the charged anode and generate soft X-rays.
1. A field emission electrode comprising a layered conductive rod comprising:
a central conductive rod having a base and side walls;
a first insulating layer covering the side walls;
a field emitter layer covering the first insulating layer; and
a second insulating layer covering the field emitter layer.
2. The layered conductive rod of claim 1 , wherein the central conductive rod is selected from the group consisting of a cylindrical rod, a rectangular rod, and a triangular rod.
3. The layered conductive rod of claim 1 , having a diameter of about 200 μm to about 1000 μm.
4. The layered conductive rod of claim 1 , wherein the central conductive rod is selected from the group consisting of a copper rod and a tungsten rod.
5. The layered conductive rod of claim 1 , wherein the central conductive rod comprises a rod having a conductive layer covering the rod.
6. The layered conductive rod of claim 5 , wherein the rod comprises a material selected from the group consisting of an insulating material and a conductive material.
7. The layered conductive rod of claim 1 , wherein the field emitter layer is a carbon-based material.
8. The layered conductive rod of claim 7 , wherein the carbon-based material is selected from the group consisting of carbon nanotubes, vulcan black, and vulcan black mixed with nanoparticle size silica.
9. The layered conductive rod of claim 1 , wherein the first insulating layer and the field emitter layer form concentric layers around the side walls of the central conductive rod.
10. The layered conductive rod of claim 1 , wherein the base of the central conductive rod is exposed.
11. The layered conductive rod of claim 10 , wherein the side walls are layered in the proximity of the base.
12. The layered conductive rod of claim 11 , wherein the first insulating layer is recessed from the base.
13. The layered conductive rod of claim 1 , wherein the layered conductive rod is an electron source.
14. A method of operating a vacuum tube comprising the layered conductive rod of claim 1 .
15. A vacuum tube comprising:
a housing; and
a field emission electrode comprising a layered conductive rod positioned in the housing, the layered conductive rod including:
a central conductive rod having a base and side walls;
a first insulating layer covering the side walls;
a field emitter layer covering the first insulating layer; and
a second insulating layer covering the field emitter layer.
16. The vacuum tube of claim 15 , wherein the field emitter layer is a carbon-based material.
17. The vacuum tube of claim 16 , wherein the carbon-based material is selected from the group consisting of carbon nanotubes, vulcan black, and vulcan black mixed with nanoparticle size silica.
18. The vacuum tube of claim 15 , wherein the base of the central conductive rod is exposed and the side walls are layered in the proximity of the base.
19. The vacuum tube of claim 15 , wherein the housing comprises a glass envelope.
20. The vacuum tube of claim 15 , wherein the housing comprises a tube of a catheter.
21. The vacuum tube of claim 15 , further comprising a second conductive rod positioned in the housing opposite the base of the central conductive rod.
22. The vacuum tube of claim 15 , further comprising a getter bead inserted within the housing.
23. The vacuum tube of claim 15 , further comprising a layer of conductive material covering at least a portion of the housing.