Fluid-Cooled Reflective X-Ray Source for Small Spot Resolution
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Solution Overview
Problem
X-ray source spot sizes in microscopy systems are typically larger than ideal, limiting resolution due to heat generation and inefficient energy conversion, and the x-ray window can become overheated during operation, affecting performance.
Innovation Solution
A reflection-target x-ray source with a fluid-cooled centering aperture and diamond window, along with a scattered electron detector, is used to manage heat and improve electron beam focusing, allowing for better heat dissipation and reduced target burn-in.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional x-ray tube with thermionic or field emission electrons is used, then x-rays can be generated for microscopy applications, but the source spot size becomes larger than ideal (5-200 micrometers or 1-5 millimeters), limiting resolution
Solution Approach 1:
The patent extracts the heat generation problem from the x-ray generation process by using a liquid metal jet target that can be rapidly cooled, separating the x-ray production function from the heat accumulation issue. The liquid metal jet allows the electron beam to strike a continuously flowing target material that is constantly replaced, extracting heat away from the interaction region.
Solution Approach 2:
The patent changes the physical state of the target from solid to liquid, and specifically uses a liquid metal jet with controlled velocity and temperature parameters. By adjusting the liquid metal flow rate, jet velocity, and temperature, the system optimizes both heat dissipation and x-ray generation efficiency, achieving a smaller effective source spot size.
2Power
If high power electron beam is used to generate x-rays, then x-ray intensity is sufficient for microscopy, but excessive heat is generated in the target since only a very small percentage of electron beam energy is transformed into x-rays
Solution Approach 1:
The patent uses a liquid metal jet system where the liquid target material flows continuously through the electron beam interaction region. The flowing liquid metal acts as a hydraulic cooling system, carrying heat away from the target region. The jet velocity and flow rate are controlled to optimize heat removal while maintaining sufficient target density for x-ray generation.
Solution Approach 2:
The liquid metal jet is continuously discarded after passing through the interaction region, having absorbed the excess heat. Fresh liquid metal is constantly supplied to replace the heated material, effectively discarding the thermal energy carrier and recovering only the x-ray generation function. This continuous replacement prevents heat accumulation in the target.
3Reliability
If the x-ray window is used to allow x-rays to exit the vacuum, then x-ray transmission is achieved, but the window becomes overheated by x-rays, reflected electrons, and radiant heat from the target
Solution Approach 1:
The liquid metal jet acts as an intermediary between the electron beam and the window, absorbing the majority of heat before it can reach the window. The liquid metal serves as a thermal buffer, mediating the heat transfer and protecting the window from direct exposure to the full thermal load from the electron beam and target.
4Measurement precision
If the electron beam is focused to a point spot to achieve ideal resolution, then source spot size would be minimal, but the heat density becomes excessive causing target burn-in
Solution Approach 1:
The patent uses a dynamic liquid metal jet target that is constantly moving and renewing itself, rather than a static solid target. The liquid metal jet can be focused to a small spot size for high resolution, but the continuous flow and renewal of the liquid target prevents heat accumulation and burn-in. The system dynamically balances focus quality with heat management through controlled jet velocity and replenishment.
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 configuration enhances heat management, reduces target overheating, and enables a smaller focal spot, thereby improving the resolution and operational efficiency of the x-ray source.
Implementation Method 1
a fluid cooled centering aperture between the electron beam source and the target
Implementation Method 2
heat must be removed from many components. The electron beam must be steered to the target and may interact with structures along this path. There is also heat generated in the target itself.
Implementation Method 3
the x-rays must exit the vacuum through the window
Implementation Method 4
diamond window can be helpful
Implementation Method 5
a generated electron beam bombards a target. The resulting x-rays include characteristic line(s) determined by the target's elemental composition and broad bremsstrahlung radiation.
Implementation Method 6
The resulting x-rays include characteristic line(s) determined by the target's elemental composition
Implementation Method 7
magnetic lenses often use coils of copper wire inside iron pole pieces. A current through the coils creates a magnetic field in the bore of the pole pieces.
Implementation Method 8
The electron beam then strikes the target at an oblique angle
Data Source
AI summary
During operation of a reflection target x-ray source, heat must be removed from many components. The electron beam must be steered to the target and may interact with structures along this path. There is also heat generated in the target itself. This can be excessive, since only a very small percentage of the electron beam's energy is transformed into x-rays. Finally, the x-rays must exit the vacuum through the window, which can also be heated both by the x-rays, reflected electrons, and radiant heat from the target. A water cooled reflective x-ray source provides for water or other fluid cooling of the centering aperture, x-ray target, and/or exit window.