X-ray Tube Cathode Shaped Emitter Sub-1mm Focal Spot
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Solution Overview
Problem
Existing X-ray tubes with flat emitting cathodes require additional focusing elements to achieve high resolution, which increases complexity and cost, and are limited by inherent beam aberrations that prevent focusing below 1.0 mm resolution.
Innovation Solution
An X-ray tube with a cathode having a shaped emitting surface, such as a concave or curved surface, that directs electron beams to a narrower focal spot without the need for external focusing elements, using methods like electrochemical machining for precise geometry formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a flat emitting surface is used in the cathode, then the structure is simple and manufacturing is easier, but the electron beams cannot be focused to a resolution of less than 1.0 mm due to inherent aberrations
Solution Approach 1:
The patent applies curvature to the emitting surface of the cathode, transforming it from a flat surface to a curved surface. This curvature enables the electron beams to be naturally focused as they emanate from different points on the curved surface, achieving a focal spot size of less than 1.0 mm without requiring additional focusing elements. The curved geometry inherently corrects beam aberrations that plague flat emitter designs.
2Manufacturing precision
If focusing elements are added to focus electron beams from a flat emitter, then the focusing resolution can be improved, but the device complexity and cost increase significantly
Solution Approach 1:
The patent extracts the focusing function from separate focusing elements and integrates it directly into the cathode structure itself. By shaping the emitting surface with appropriate curvature, the cathode performs both emission and focusing functions simultaneously, eliminating the need for additional quadrupole magnets or other focusing elements that would increase device complexity and cost.
Solution Approach 2:
The patent merges the emission function and focusing function into a single integrated component - the cathode. The curved emitting surface simultaneously serves as both the electron source and the focusing element, combining what were previously separate functions (emission from flat surface + separate focusing elements) into one unified structure.
3Manufacturing precision
If a shaped emitting surface is used to focus electron beams, then the focal spot size can be reduced below 1.0 mm, but the manufacturing process becomes more complex
Solution Approach 1:
The patent changes the geometric parameters of the emitting surface from flat to curved, with specific curvature radii optimized for the desired focal spot size. This parameter change enables sub-1.0 mm focusing while the curvature can be achieved through standard manufacturing techniques such as precision machining or forming processes applied during cathode fabrication.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables focusing of electron beams onto a focal spot smaller than 1.0 mm without additional focusing elements, reducing complexity and cost while minimizing aberrations, and allowing for precise control of the emitting surface geometry.
Implementation Method 1
electrons emitted from the cathode side impinge on the anode target
Data Source
AI summary
An emitter for a cathode of an X-ray tube is provided that includes a shaped emitting surface. The emitting surface is shaped in a suitable process in order to enable the emitting surface to focus electron beams emitted from the emitting surface on a focal spot on a target of less than 1.0 mm without the need for any additional focusing elements in the X-ray tube.