Planar filament with focused, central electron emission
AssigneeMoxtek, Inc.
InventorsKasey Otho Greenland, Todd S. Parker
Life of this patent
Estimating the term…
Abstract
A planar filament for an x-ray tube can have a different cross-sectional area at different locations. In regions of smaller cross-sectional area, there can be higher current density, and thus increased heating and higher temperature of the wire. In regions of larger cross-sectional area, there can be lower current density, and thus decreased heating of the wire. Regions of larger cross-sectional area can also be stronger, thus reducing early filament failures. Wider regions can have increased area for electron emission. By adjusting the cross-sectional area and width of the wire at different locations, electron emission can be largely confined to a center of the filament, and filament life can increase.
Claims20
An x-ray tube comprising:
- a cathode and an anode electrically insulated from one another, the cathode including a filament configured to emit electrons towards the anode, and the anode configured to emit x-rays out of the x-ray tube in response to impinging electrons from the filament;
- the filament comprises an elongated wire in a plane extending non-linearly in between a pair of electrodes, the filament capable of being heated by an electrical current through the elongated wire due to a voltage differential across the pair of electrodes;
- the filament includes a low-region and a pair of outer-high-regions;
- the low-region is electrically-coupled between the pair of outer-high-regions;
- the low-region is configured to have lower current density during operation than the pair of outer-high-regions due to a larger thickness in the low-region than a thickness in the pair of outer-high-regions;
- and
- wherein the filament has a planar face and the larger thickness in the low-region extends perpendicular from the planar face.
Dependencies are inferred from the claim text.