X-ray tube anode thermal expansion control
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Solution Overview
Problem
Small and portable x-ray tubes face challenges in maintaining positional stability of the x-ray spot due to temperature fluctuations, as they cannot accommodate large heat removal pathways and liquid coolant-based cooling methods are impractical for these devices.
Innovation Solution
The design includes an electrically-conductive anode with a target material and an electrically-insulated cathode, a heatsink with an array of fins and fans for air cooling, and an electrical-insulator with a high thermal conductivity to minimize thermal expansion and improve heat transfer, reducing the displacement of the target material and maintaining x-ray spot stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If large pathways for heat removal are used, then heat dissipation is improved, but device size increases
Solution Approach 1:
The patent applies local quality by concentrating heat dissipation functionality in a localized heatsink structure with high thermal conductivity material directly attached to the anode, rather than distributing heat removal pathways throughout the entire device. This allows efficient heat removal from the critical hot spot while maintaining compact overall device dimensions.
Solution Approach 2:
The patent employs composite materials by using high thermal conductivity material (such as diamond or cubic boron nitride) for the heatsink structure, which combines exceptional thermal properties with compact form factor. This composite approach enables superior heat dissipation performance in a space-efficient manner.
2Loss of energy
If liquid coolant heat exchanger is used, then heat removal efficiency is improved, but device complexity and portability are worsened
Solution Approach 1:
The patent extracts the liquid coolant heat exchanger from the system entirely, replacing it with a solid-state heatsink solution. This removal of the complex fluid cooling system eliminates pumps, tubes, and coolant management while maintaining effective heat removal through direct thermal conduction to ambient air.
Solution Approach 2:
The patent substitutes the mechanical liquid cooling system with a thermal conduction-based solid state heatsink. The mechanical complexity of pumps, valves, and fluid circulation is replaced by passive thermal conduction through high conductivity material, dramatically simplifying the device.
3Loss of energy
If anode thermal expansion is not controlled, then heat transfer is improved, but x-ray spot stability deteriorates
Solution Approach 1:
The patent applies preliminary anti-action by pre-compensating for thermal expansion through the rigid constraint provided by the high thermal conductivity heatsink. The heatsink's rigid structure counteracts the anode's tendency to expand thermally, maintaining precise target positioning before spot instability can occur.
Solution Approach 2:
The patent changes the thermal parameters of the system by introducing high thermal conductivity material that fundamentally alters the temperature distribution and thermal expansion characteristics of the anode assembly, thereby stabilizing the x-ray spot position during operation.
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 solution effectively reduces target material displacement and maintains x-ray spot stability in small x-ray tubes by minimizing thermal expansion and improving heat transfer, enabling stable operation without the need for a heat exchanger.
Implementation Method 1
A first fan can be attached to the first distal ends of the array of fins, oriented to face the base, and configured to direct an airstream towards the base. A second fan can be attached to the second distal ends of the array of fins, oriented to face away from the base, and configured to draw the airstream from the base.
Implementation Method 2
The x-ray tube can include a heatsink with a base located closer to the anode and an array of fins extending from the base away from the anode
Implementation Method 3
an electrical-insulator encircling the anode and electrically insulating the cathode from the anode and a heatsink attached to and in thermal contact with the electrical-insulator
Implementation Method 4
a target material configured for production and emission of x-rays in response to impinging electrons
Implementation Method 5
a target material configured for production and emission of x-rays in response to impinging electrons
Data Source
AI summary
An x-ray tube can provide x-ray spot stability, even for a small x-ray tube. The x-ray tube can have small target displacement, where target displacement is a displacement of the target material, towards the electron-emitter, along a longitudinal-axis of the anode, from x-ray powered-off state to stable operation, based on elongation of the anode. The x-ray tube can include a heatsink with an array of fins extending away from a base in opposite directions. A first fan can be attached to one end of the array of fins, oriented to face the base, and configured to direct an airstream towards the base. A second fan can be attached to opposite ends, oriented to face away from the base, and configured to draw the airstream from the base. Plate(s) can be located on sides of the fins to direct air flow from the first fan to the second fan.