Claims
- 1. A field emission cold cathode comprising:
a cathode having a cathode surface; and a carbon velvet material bonded to the cathode surface.
- 2. The cold cathode of claim 1, wherein the carbon velvet material is coated with a cesiated salt.
- 3. The cold cathode of claim 1, wherein the carbon velvet is coated with a cesiated salt selected from the group comprising, cesium iodide, cesium tellurate or cesium bromide.
- 4. The cold cathode of claim 1, wherein the cathode is operated in any vacuum higher than 10−3 torr.
- 5. The cold cathode of claim 1, wherein the carbon velvet material is Vel-Black®.
- 6. A carbon velvet material field emission cold cathode comprising:
a carbon velvet material coated with a low work function cesiated salt; a cathode base surface; and bonding to bond the carbon velvet material to the cathode base surface.
- 7. The cold cathode of claim 6, wherein the carbon velvet material is Vel-Black®.
- 8. The cold cathode of claim 6, wherein the cathode base surface is metallic and the bonding is a conductive epoxy.
- 9. The cold cathode of claim 6, wherein the cathode base surface is a carbon substrate and the bonding is formed through pyrobonding.
- 10. The cold cathode of claim 6, wherein the cesiated salt is selected from the group comprising, cesium iodide, cesium tellurate or cesium bromide.
- 11. The cold cathode of claim 9, wherein the carbon velvet material is coated with the low work function cesiated salt by spraying a solution of the cesiated salt and de-ionized water onto the carbon velvet material, placing the cathode into a vacuum oven evacuated to less than 1 torr., and baking the cathode at over 100 degrees centigrade for a period sufficient to remove the de-ionized water.
- 12. A method for coating a carbon velvet material bonded to a cathode surface for use as a field emission cold cathode in a vacuum tube, the method comprised of:
mixing a low work function cesiated salt and de-ionized water to form a solution; spraying the carbon velvet material with the cesiated salt solution using a spraying means pressurized by dry nitrogen; baking the cesiated salt solution coated carbon velvet material at over 100 degrees centigrade for approximately an hour in a vacuum oven evacuated to less than 1 torr.; and venting to atmospheric pressure using dry nitrogen.
- 13. The method of claim 12, wherein the cesiated salt is selected from the group comprising, cesium iodide, cesium tellurate or cesium bromide.
- 14. A method of making a field emission cold cathode, the method comprised of:
forming a solution of cesiated salt; coating a carbon velvet material with the cesiated salt solution; and bonding the carbon velvet material to a cathode surface.
- 15. The method of making a field emission cold cathode of claim 14, wherein the carbon velvet material is Vel-Black®.
- 16. The method of making a field emission cold cathode of claim 14, wherein the cesiated salt is selected from the group comprising, cesium iodide, cesium tellurate or cesium bromide.
- 17. A method of applying a low work function cesiated salt to a carbon velvet material so that the carbon velvet material can act as a field emission cold cathode in a vacuum tube when the material is bonded to a cathode surface, the method comprised of chemical vapor deposition such that cesiated salt crystals form near the tips.
- 18. A method of applying a cesiated salt to a carbon velvet material so that the carbon velvet material can act as a field emission cold cathode in a vacuum tube when the material is bonded to a cathode surface, the method comprised of dipping the tips of the carbon velvet material into a molten solution of the cesiated salt and allowing the carbon velvet material to cool.
FEDERAL RESEARCH STATEMENT
[0001] The conditions under which this invention was made are such as to entitle the Government of the United States under paragraph I(a) of Executive Order 10096, as represented by the Secretary of the Air Force, to the entire right, title and interest therein, including foreign rights.