Filament for X-ray cathode

摘要

Embodiments include an X-ray cathode filament, filament system, process to manufacture the filament and process to use the filament, where the filament includes a planar substrate, such as of tungsten, having a top surface coated with a coating of carburized tungsten (e.g., W2C) and thoria (ThO2). A first electron beam is emitted from the coating through a thermionic effect at a first temperature, such as when the filament is heated to between 1700 and 1900 degrees Celsius by running an electrical current through the filament. At this temperature, a second electron beam may be caused by (1) a reaction that includes creating thorium (Th) in the coating, and (2) the thorium diffusing to uncoated surfaces of the substrate from which the second electron beam is emitted. The filament may also have slots forming a zipper shape, forming a square switchback shape, or forming a rectangular labyrinth shape to reduce the current required to heat the filament.

主权项

1. An x-ray cathode filament comprising:
a substrate comprising a planar substrate of a substrate material; and a coating comprising carburized tungsten (W2C) and thoria (ThO2) disposed upon a first surface the substrate; wherein a first electron beam emits from the coating through a thermionic effect at a first temperature, wherein a second electron beam emits at the first temperature from uncoated surfaces of the substrate that the thorium diffuses to.