X-ray tube electron shield with expansion joints for thermal stress management
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Solution Overview
Problem
X-ray generating devices face issues with backscattered electrons causing thermal damage and aperture failure due to excessive heat, leading to reduced operating life and increased costs for replacement.
Innovation Solution
An electron shield with expansion joints and a refractory material composition, including a bimetallic configuration with slots for thermal expansion, to absorb backscattered electrons and manage heat effectively, reducing mechanical stresses and particulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the aperture shield is made from a single piece of material, then the structure is simple and easy to manufacture, but thermal stresses cause plastic deformation, cracking, and delamination
Solution Approach 1:
The aperture shield is divided into multiple segments or pieces that are joined together, allowing each segment to expand and contract independently under thermal stress. This segmentation prevents the buildup of thermal stresses that would cause plastic deformation, cracking, and delamination in a monolithic structure, while still maintaining structural integrity through the joints between segments.
2Measurement precision
If the aperture shield captures more backscattered electrons, then image quality improves, but thermal damage and particulation rates increase
Solution Approach 1:
By segmenting the aperture shield into multiple pieces with joints between them, the structure can capture sufficient backscattered electrons to maintain image quality while allowing each segment to independently accommodate thermal expansion. This prevents the thermal stress accumulation that leads to particulation and thermal damage, thus resolving the contradiction between electron capture efficiency and thermal damage resistance.
Solution Approach 2:
The aperture shield design changes the physical parameters of the structure by introducing joints that alter the thermal and mechanical properties. These joints allow for controlled movement and stress distribution, changing how the shield responds to thermal loads while maintaining its electron-capturing function, thereby reducing particulation rates despite capturing more backscattered electrons.
3Productivity
If higher power input is used, then productivity increases, but thermal stresses cause aperture failure
Solution Approach 1:
The segmented aperture shield structure enables higher power input operations by distributing thermal stresses across multiple segments and joints. Each segment can expand and contract independently, preventing the catastrophic failure that would occur in a monolithic structure under high thermal loads, thus extending operating life while maintaining high productivity.
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
The design enhances the electron shield's ability to withstand thermal stresses, increases operating life, and reduces electrical arcs, allowing for higher power input and improved image quality by capturing a greater percentage of backscattered electrons.
Implementation Method 1
the energy associated with the backscattered electrons heats the aperture causing it to expand
Implementation Method 2
the energy associated with the backscattered electrons heats the aperture causing it to expand. At a certain input power level the amount of expansion exceeds the aperture material's yield point causing plastic deformation due to thermal stresses
Implementation Method 3
An electron shield with expansion joints and a refractory material composition, including a bimetallic configuration with slots for thermal expansion
Implementation Method 4
a bimetallic configuration with slots for thermal expansion
Data Source
AI summary
An x-ray tube electron shield is disclosed for interposition between an electron emitter and an anode configured to receive the emitted electrons. The electron shield includes expansion joints to accommodate thermal expansion.