Embedded X-Ray Target Structure for Thermal Stress Control
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Solution Overview
Problem
Existing X-ray targets face challenges in embedding materials like tungsten in diamond substrates due to difficulties in forming deep holes, thermal expansion mismatches leading to defects, and poor thermal contact, resulting in overheating and reduced X-ray radiation.
Innovation Solution
An X-ray target design featuring a substrate with high thermal conductivity, such as diamond, and target features embedded in an embedding layer like silicon carbide, which provides good adhesion and thermal conduction without penetrating the substrate, using materials with similar thermal expansion coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the target feature is embedded deep in the substrate to increase thermal conduction, then thermal load capacity is improved, but manufacturing difficulty increases and thermal expansion mismatch causes defects
Solution Approach 1:
An embedding layer made of silicon carbide is introduced as an intermediary between the diamond substrate and the tungsten target feature. This embedding layer has thermal expansion and thermal conductivity properties that are intermediate between diamond and tungsten, facilitating gradual thermal adaptation and reducing stress concentration at interfaces while enabling effective heat transfer from the target feature to the substrate.
2Reliability
If the target feature is embedded deep in the substrate to improve thermal contact, then thermal conduction is improved, but the risk of defects and cracks increases due to thermal expansion mismatch
Solution Approach 1:
The embedding layer changes the thermal and mechanical parameters gradually from the diamond substrate to the tungsten target feature. By using silicon carbide with intermediate properties, the system transitions smoothly between materials with different thermal expansion coefficients, reducing thermal stress and preventing defect formation while maintaining reliable thermal contact.
3Ease of manufacture
If a thin embedded target feature is used to reduce manufacturing difficulty, then ease of manufacture is improved, but X-ray radiation output decreases
Solution Approach 1:
The target feature is designed with optimized local dimensions and geometry within the embedding layer, creating a configuration that maximizes X-ray generation efficiency. The embedding layer provides a suitable matrix that supports an effectively sized target feature while maintaining manufacturability, allowing the target feature to have sufficient volume for high X-ray yield without requiring deep substrate penetration.
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
Enhances thermal load capacity, reduces thermal stress, and maintains efficient X-ray generation by ensuring effective thermal conduction and alignment of target features, minimizing overheating and defects.
Implementation Method 1
The substrate is selected to have a sufficiently high thermal conductivity so that heat generated by an incident electron beam may be distributed from the point of impact
Implementation Method 2
The X-ray radiation is primarily generated as bremsstrahlung, although characteristic emission lines also contribute
Implementation Method 3
The X-ray radiation is primarily generated as bremsstrahlung, although characteristic emission lines also contribute
Implementation Method 4
The material in the embedding layer can be selected to provide good adhesion to the substrate and the target material, to enable formation of suitable holes or indentations for the target features, and to provide for good thermal conduction from the target feature(s) to the substrate
Data Source
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Figure 3(a)~3(c)
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AI summary
A target for an X-ray source is disclosed. The X-ray target comprises a substrate having a top face, and an embedding layer provided on the top face of the substrate. A target feature operative to generate X-ray radiation upon electron impact is at least partly embedded in the embedding layer without reaching into the substrate. Preferably, an extension of the target feature in a direction orthogonal to the top face is larger than an extension of the target feature in a direction parallel to the top face. An X-ray source comprising such X-ray target is also disclosed.