Dual-Stage Electron Beam Steering for Stable X-Ray Target Spots
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Solution Overview
Problem
Laboratory x-ray sources face challenges such as target burn-in, which leads to a needle-like hole drilled by the electron beam, causing variations in the x-ray spectrum and affecting tomographic reconstruction quality. Additionally, there are issues with maintaining the stability of the x-ray spot position, leading to center-shifts and axial spot movements, which impact the geometric magnification and resolution of x-ray projection microscopes.
Innovation Solution
The solution involves active control of the spot position using dual-stage steering to maintain the electron beam through the center of the magnetic lens, thereby stabilizing the x-ray spot on the target. This method also allows for the selection of a new x-ray emission spot after burn-in occurs, ensuring consistent x-ray production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed electron beam is used to generate x-rays, then the x-ray source is simple to operate, but target burn-in occurs leading to needle-like holes and spectrum variations
Solution Approach 1:
The patent applies dynamic beam steering using electromagnetic fields to continuously move the electron beam across the target surface. This dynamic approach prevents static burn-in by distributing electron impact across multiple locations, thereby extending target life and maintaining spectral stability while keeping the system relatively simple to operate.
Solution Approach 2:
The system performs preliminary beam positioning and scanning operations to identify and avoid previously irradiated areas on the target. By pre-mapping the target surface and tracking irradiation history, the system proactively prevents burn-in before needle-like holes form, maintaining target integrity and consistent x-ray spectrum.
2Reliability
If the electron beam is steered to move the x-ray spot, then target burn-in is prevented, but spot position stability deteriorates causing center-shifts and axial movements
Solution Approach 1:
The patent implements feedback control by monitoring the actual electron beam position on the target and adjusting steering parameters in real-time. This closed-loop system compensates for drift and positional variations, maintaining spot stability at the desired location while still enabling beam movement to prevent burn-in through controlled scanning patterns.
Solution Approach 2:
The system uses dynamic beam steering with controlled motion patterns that balance two competing requirements: moving the beam enough to prevent burn-in while maintaining positional stability for high-resolution imaging. The beam follows predetermined scan patterns that revisit the same location only after sufficient time has passed to prevent damage accumulation.
3Manufacturing precision
If a small x-ray source spot is used for high resolution, then image quality improves, but the target is more susceptible to burn-in
Solution Approach 1:
The patent segments the target usage by dividing the electron beam's path into multiple discrete locations. Instead of concentrating all beam current on a single small spot, the system rapidly switches between multiple adjacent locations, effectively distributing the thermal load. This allows maintaining a small effective spot size for high resolution while preventing any single point from overheating or forming burn-in holes.
Solution Approach 2:
The system employs periodic scanning patterns where the electron beam repeatedly cycles through a set of predetermined locations on the target. This periodic motion ensures that no single location receives continuous bombardment, allowing heat dissipation between cycles and preventing burn-in while maintaining a consistently small effective spot size for high-resolution imaging.
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 approach effectively mitigates spot shift and drift, stabilizes the x-ray spot position, and extends the life of x-ray targets by preventing burn-in, thereby improving the resolution and quality of x-ray microscopy images.
Implementation Method 1
The resulting x-rays include characteristic line(s) determined by the target's elemental composition and broad bremsstrahlung radiation
Implementation Method 2
The resulting x-rays include characteristic line(s) determined by the target's elemental composition
Implementation Method 3
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 4
steering the electron beam to a desired location on the target using a first and a second steering system distributed along a flight tube
Data Source
AI summary
A method for controlling an x-ray source comprises generating an electron beam for striking the target to generate x-rays and steering the electron beam to a desired location on the target using a first and a second steering system distributed along a flight tube. In this way, the beam can be steering to the desired location while also passing through the center of a focusing lens to maintain optimal beam characteristics. Also possible is scanning the electron beam over the target to find a fiducial mark. Then, a desired location can be found as an offset from this mark.