X-ray Anode Focal Track Thermal Compliance
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Solution Overview
Problem
X-ray sources in CT imaging systems face significant thermal stress due to rapid heating and cooling cycles, leading to 'mud-flat cracking' of the anode focal track, which reduces the lifespan and performance of the x-ray source.
Innovation Solution
A thermally-compliant focal track region is created on the x-ray anode with a pattern of discrete expanses and gaps, allowing for controlled thermal expansion and contraction, thereby reducing the risk of cracking through electrochemical etching or laser ablation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a continuous focal track surface is used to generate x-rays, then x-ray production efficiency is improved, but thermal stress cracking occurs during thermal cycling
Solution Approach 1:
The continuous focal track surface is divided into discrete focal spots arranged in a circular pattern. Each focal spot is separated by gaps, creating a segmented structure that allows independent thermal management of each region while maintaining effective x-ray generation areas.
Solution Approach 2:
Different regions of the anode surface are given different properties: focal spots have high atomic number materials for efficient x-ray generation, while gap regions provide thermal relief and stress accommodation. This local differentiation resolves the contradiction between maintaining continuous effective areas and preventing thermal stress accumulation.
2Power
If high electron beam power is applied to the focal track, then x-ray output intensity is improved, but thermal stress and cracking increase
Solution Approach 1:
By segmenting the focal track into discrete spots, the thermal load from high-power electron beams is distributed across multiple separated regions rather than concentrated in a continuous area. The gaps between spots provide thermal pathways that reduce overall thermal stress accumulation.
Solution Approach 2:
The focal track is arranged in a circular pattern in the radial dimension, distributing the electron beam impact across multiple spatial locations. This dimensional arrangement allows heat to dissipate in multiple directions and reduces localized thermal stress concentrations that would occur in a linear or single-area focal region.
3Power
If the focal track surface is made smooth and continuous, then electron deceleration efficiency is improved, but plastic deformation and cracking occur during cooling
Solution Approach 1:
The smooth continuous surface is replaced with discrete focal spots that have smooth surfaces for efficient electron deceleration, separated by gaps that prevent crack propagation. During cooling, the gaps allow the material to contract without generating tensile stresses that would cause cracking in a continuous surface.
Solution Approach 2:
The problematic continuous surface structure is extracted and replaced with discrete focal spots. By removing the continuous material connections, the harmful thermal stress transmission path is eliminated while retaining the essential function of electron deceleration in the focal spot regions.
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 thermally-compliant focal track region enhances the durability and lifespan of the x-ray source by preventing plastic deformation and uncontrolled cracking, allowing for higher electron beam powers and improved image quality during thermal cycling.
Implementation Method 1
A focal track region of an x-ray anode is electrochemically etched
Implementation Method 2
The thermally-compliant focal track region comprises a pattern of discrete relative expanses and gaps
Implementation Method 3
When the high energy electrons from the cathode strike the surface of the focal track of the anode, the electrons are decelerated by the high density focal track
Implementation Method 4
The deceleration of the electrons from the cathode against the surface of the x-ray anode results in the x-ray source
Implementation Method 5
The rapid heating of the small, thin surface zone causes a substantial increase in the local target surface temperature
Implementation Method 6
The rapid heating of the small, thin surface zone causes a substantial increase in the local target surface temperature, and the generation of enormous thermal stresses
Implementation Method 7
through electrochemical etching or laser ablation techniques
Data Source
AI summary
A focal track region of an x-ray anode in an example is electrochemically etched. In a further example, an x-ray anode comprises a thermally-compliant focal track region for impingement of electrons from an x-ray cathode to create an x-ray source. The thermally-compliant focal track region comprises a pattern of discrete relative expanses and gaps.