Grid controlled electron source and method of making same
US3967150A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 31, 1975 |
| Grant date | Jun 29, 1976 |
| Priority date | — |
| Expiry date | Jan 31, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J23/065
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A grid-controlled electron source comprises an apertured grid spaced in front of a thermionic cathode. Areas of the cathode directly behind the grid conductors are made non-emissive by a bonded surface layer of non-emissive material such as zirconium. On porous metal cathodes impregnated with active emitting material the metal surface may be sealed with a dense layer of inactive metal under the non-emissive layer to prevent chemical reaction of the latter with the emitting material. Methods of depositing the surface layers in the desired pattern include coating the cathode's entire large-scale surface contour, followed by machining small concave dimples into the surface, thereby removing the non-emissive layer from the dimpled surfaces from which small beamlets of electrons are focused between the grid conductors without grid interception. Another method is to mask the desired non-emissive areas with an apertured mask having solid elements registered with the desired positions of the grid conductors. The surface behind the mask apertures is coated with an inactive powder, then the mask is removed and the non-emissive layer or layers deposited in the uncoated, previously masked path…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.