Cathode structures for X-ray tubes
AssigneeVarian Medical Systems Technologies, Inc.
InventorsJames Arnold, Steve Bandy, Gary Virshup
Life of this patent
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Abstract
An apparatus and method comprising a cathode structure which can be a cylindrical filament coiled in a helix or which can be constructed of a ribbon or other suitable shape. The cathode structure can be heated by passage of an electrical current, or by other means such as bombardment with energetic electrons. Selected portions of the surface of the cathode structure have an altered property with respect to the non-selected portions of the surface. In one embodiment, the altered property is a curvature. In another embodiment, the altered property is a work function. By altering the property of the selected portions of the surface, the electron beam intensity is increased, and the width is decreased.
Claims69
An apparatus comprising:
- a cylindrical filament to function as a cathode of an X-ray tube having a surface,
- wherein a selected portion of the surface have at least one altered property with respect to a non-selected portion of the surface.
A method comprising:
- providing a cylindrical filament for a cathode of an X-ray tube, wherein the cylindrical filament has a surface;
- selecting a portion of the surface of the cylindrical filament;
- and
- altering a property of the selected portion to emit electrons preferentially from the selected portion.
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Dependencies are inferred from the claim text.