X-ray Tube Anode Heat Sink with Ceramic Fins
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Solution Overview
Problem
X-ray tubes operating at high voltages face challenges in maintaining dielectric strength and efficient heat dissipation due to the limitations of existing heat sinks, which often require increased size and are prone to mechanical stress from thermal expansion differences between metal anodes and ceramic heat sinks.
Innovation Solution
A heat sink design featuring a metal base body with thermally conductive ceramic heat dissipation elements, such as aluminum nitride or silicon carbide, arranged in a configuration that allows for increased insulation distance and stress compensation through a press fit connection, enhancing both thermal conductivity and electrical insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a metal heat sink is used to cool the anode, then heat dissipation efficiency is improved, but the insulation distance to components at reference potential must be increased to prevent voltage flashovers
Solution Approach 1:
The heat sink is divided into two distinct parts: a metal base body in direct thermal contact with the anode for efficient heat dissipation, and ceramic heat dissipation elements attached to the base body that extend into the insulation space. This segmentation allows each material to perform its optimal function while resolving the contradiction between thermal conductivity and electrical insulation.
Solution Approach 2:
The heat sink combines metal and ceramic materials in a composite structure. The metal base body provides high thermal conductivity for heat removal, while the ceramic elements provide electrical insulation. This composite approach enables the heat sink to simultaneously achieve efficient cooling and maintain required insulation distances, eliminating the need to increase overall system size.
2Reliability
If a ceramic heat sink is used to maintain insulation distance, then dielectric strength is improved, but manufacturing cost increases due to special molds and material requirements
Solution Approach 1:
The heat sink is segmented into a metal base body that is easier and more cost-effective to manufacture, and ceramic heat dissipation elements that are only used where electrical insulation is required. This reduces the overall amount of expensive ceramic material needed compared to a fully ceramic heat sink, while still achieving the required dielectric strength.
Solution Approach 2:
Ceramic material is applied locally only in regions where electrical insulation is needed, rather than throughout the entire heat sink structure. The metal base body handles the thermal management functions, while ceramic elements are strategically positioned to provide insulation where high voltage differential exists, optimizing both performance and cost.
3Reliability
If a ceramic heat sink is used to improve insulation, then dielectric strength is improved, but mechanical stress from thermal expansion differences damages the heat sink connection
Solution Approach 1:
The metal base body acts as an intermediary between the anode and the ceramic heat dissipation elements. It provides a transition zone that accommodates the difference in thermal expansion coefficients, absorbing mechanical stress through its own thermal expansion while maintaining secure thermal and mechanical contact with both the anode and ceramic elements.
Solution Approach 2:
The design accounts for thermal expansion by allowing the metal base body to expand and contract within its operational temperature range, absorbing the mechanical stress that would otherwise be transmitted to the ceramic elements. This parameter change (thermal expansion of the metal base) protects the more brittle ceramic material from damage.
4Reliability
If the X-ray tube housing is enlarged to accommodate increased insulation distances, then voltage flashover prevention is improved, but device compactness deteriorates
Solution Approach 1:
The composite heat sink structure enables the housing to maintain its original compact dimensions by providing electrical insulation through the ceramic elements integrated into the heat sink itself, rather than requiring increased clearance between the anode and housing. The ceramic elements extend the insulation distance locally without increasing overall system volume.
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 design effectively manages heat dissipation and maintains dielectric strength while minimizing mechanical stress, allowing for compact X-ray tube designs even at high voltages, and combines cost-effective materials for improved performance.
Implementation Method 1
a base body (10.1, 10.2, 10.3, 10.4) made of a metal with good thermal conductivity
Implementation Method 2
the component to which the heat sink is attached can be cooled by thermal radiation and, in particular, convection
Implementation Method 3
the component to which the heat sink is attached can be cooled by thermal radiation and, in particular, convection
Implementation Method 4
the anode metal—usually copper—has a higher coefficient of thermal expansion than the externally mounted ceramic heat sink
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
The present invention relates to an x-ray tube having a self-heating anode which carries during operation a high voltage, preferably more than 120 kV, particularly preferably more than 300 kV, wherein a cooling body (4) is connected to the anode in a heat-conductive manner, said cooling body having a base body (10.4) of a metal with a heat-absorbing surface for coupling with the anode as a heat source and a heat-dissipating surface (14.4) which is enlarged by heat-dissipating elements (16.4) connected to the base body (10.4). According to the invention, the heat-dissipating elements (16.4) are made of an electrically insulating material which has a thermal conductivity in the order of magnitude of the metal of the base body (10.4), wherein the heat-dissipating elements (16.4) have a height (H) starting from the base body (10.4) of the cooling body (4) such that a sufficient dielectric strength with respect to the surroundings of the x-ray tube is achieved whilst taking into account the high voltage and an insulation medium surrounding the heat-dissipating elements (16.4).