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US 3,967,150 AGranted
Grid controlled electron source and method of making same
AssigneeVarian Associates, Inc.
InventorsErling L. Lien, George V. Miram, Richard B. Nelson
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AssigneeVarian Associates, Inc.
InventorsErling L. Lien, George V. Miram, Richard B. Nelson
Estimating the term…
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 paths. Lastly, the inactive powder is removed, uncovering the emissive surface areas.
A grid-controlled electron source comprising, a thermionic cathode and a control grid spaced adjacent said cathode, said grid comprising multiple apertures separated by conductive members, said cathode having a surface facing said control grid, said surface comprising, electron emissive areas facing said multiple apertures, and non-emissive areas facing said conductive members, said non-emissive areas comprising deposited portions of a layer of non-emissive material on said surface facing said control grid.
A process for fabricating a thermionic cathode comprising an emitter-base material, non-emissive surface areas, and multiple emissive surface areas, said process comprising the steps of;
A process for fabricating a thermionic cathode comprising a porous metal body, a source of activating material dispersed in the pores of said body, multiple electron emissive surface areas and non-emissive surface areas, said process comprising the sequential steps of;
A process for fabricating a thermionic cathode comprising an electron emissive base material, emissive surface areas and non-emissive surface areas, said process comprising the steps of;
A process for fabricating a thermionic cathode comprising a porous metal base material, an activating material dispersed in the pores of said base material, electron emissive surface areas and non-emissive surface areas, said process comprising the steps of;
Dependencies are inferred from the claim text.