Segmented X-ray Tube Emitter with Low Work Function Layer
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Solution Overview
Problem
High-end X-ray tubes face issues with temperature gradients and hot spots in directly heated flat emitters, leading to material evaporation, structural wear, and divergent electron beams, which affect focal spot size and image quality.
Innovation Solution
The emitter device features a plurality of ligaments with slots for physical separation and a low work function layer on select portions, ensuring uniform temperature distribution and parallel electron beams, reducing hot spots and mechanical wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If directly heated flat emitters are used to achieve high electrical resistance, then the required high electrical resistance is obtained, but temperature gradients and hot spots arise leading to material evaporation and emitter failure
Solution Approach 1:
The emitter is divided into multiple discrete heating zones or segments along the electron beam path. Each segment can be independently controlled or has different resistance characteristics, allowing the temperature profile to be optimized along the length of the emitter. This segmentation prevents the formation of concentrated hot spots by distributing the heating more evenly throughout the emitter structure.
Solution Approach 2:
Different portions of the emitter are given different electrical resistance properties or geometric characteristics to create localized temperature control. The emitter may have varying thickness, material composition, or cross-sectional area at different locations to achieve more uniform heat distribution. This local variation in properties allows each region to contribute appropriately to electron emission without creating excessive hot spots.
2Reliability
If high intensity X-rays are generated for better image quality, then image quality improves, but the probability of breakdown and operational failures increases
Solution Approach 1:
The emitter design incorporates dynamic control capabilities that allow the operating parameters to be adjusted in real-time. The emitter can adapt its emission characteristics based on the required X-ray intensity, distributing the stress more evenly over time. This may include pulsed operation modes, variable voltage application, or dynamic reconfiguration of the emitter zones to prevent breakdown while maintaining high intensity capability when needed.
3Productivity
If voltage is increased to generate electron beams, then electron beam intensity increases, but structural wear and operational failures increase
Solution Approach 1:
The emitter is divided into multiple segments that can share the electrical stress and heating load. By distributing the high voltage application across multiple zones rather than concentrating it in a single region, the emitter can achieve high electron beam intensity without any single point experiencing excessive stress that would lead to structural wear or failure.
4Manufacturing precision
If focal spot size is reduced for higher image quality, then image quality improves, but the requirements for temperature control and emitter precision increase
Solution Approach 1:
The emitter is divided into multiple precisely-controlled segments that can be independently optimized for focal spot formation. Each segment contributes to a specific portion of the focal spot, allowing for precise control of the electron beam geometry. This segmentation enables the creation of small, well-defined focal spots while distributing the thermal load across multiple zones, reducing the temperature control difficulty compared to a single concentrated emission point.
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
This configuration enhances electron beam focus, maintains a robust focal spot, and extends the emitter's usable life by preventing divergent beams and uneven temperature distribution, resulting in improved image quality and longer device lifespan.
Implementation Method 1
a low work function layer disposed on select portions of the plurality of ligaments
Implementation Method 2
an applied voltage to the emitter device... an electric field resulting from the applied voltage
Implementation Method 3
The target may produce X-ray radiation as a result of impact of the stream of electrons
Data Source
AI summary
An emitter device having an emission surface includes a plurality of ligaments configured to emit electrons in response to an applied electric field resulting from an applied electrical voltage. Further, the emitter device includes a plurality of slots configured to provide physical separation between two or more adjacently disposed ligaments of the plurality of ligaments, where one or more slots of the plurality of slots define an electrical path. Moreover, the emitter device includes a low work function layer disposed on at least a portion of a ligament of the plurality of ligaments.