Dual Source XRF System for Sulfur Masking
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Solution Overview
Problem
XRF systems face challenges in analyzing a wide range of elements, particularly when high concentrations of one element mask or interfere with the detection of low concentrations of other elements, as seen in fuel and oil samples, where sulfur interference makes it difficult to measure low levels of aluminum and silicon.
Innovation Solution
A dual-source XRF system is implemented, where one x-ray source optimally excites high concentration elements while minimizing excitation of low concentration elements, and a monochromator is used to produce a quasi mono-energetic x-ray source, allowing for sequential measurement and correction of results to accurately determine both high and low concentration elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single x-ray tube is used to analyze a wide range of elements, then the system complexity is reduced, but the measurement precision deteriorates due to high concentration elements masking low concentration elements
Solution Approach 1:
The patent divides the analysis into two separate measurement sequences using two different x-ray tube configurations. The first tube (e.g., Rhodium anode) is optimized for measuring high concentration elements like sulfur, while the second tube (e.g., Molybdenum anode with monochromator) is optimized for measuring low concentration elements like aluminum and silicon. This segmentation allows each measurement to be optimized for its specific target elements, resolving the masking problem without requiring a single complex multi-purpose tube.
Solution Approach 2:
Each x-ray tube is configured with specific local qualities tailored to its measurement purpose. The first tube uses a Rhodium anode with specific filtration to optimize excitation for high Z elements. The second tube uses a Molybdenum anode with a monochromator to produce monochromatic radiation at a specific energy (e.g., Mo-Lα line) that efficiently excites low Z elements while avoiding sulfur interference. This local optimization of quality for each measurement task resolves the contradiction.
2Measurement precision
If multiple x-ray sources are used to measure different elements, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent implements a universal XRF system that can perform multiple measurement functions through two tubes. Both tubes share common components including the sample chamber, detector, and data processing system. The system can sequentially switch between different tube configurations to handle various analytical requirements - measuring high concentration elements, measuring low concentration elements, or even analyzing different sample types. This multi-functionality approach reduces overall device complexity compared to having separate dedicated instruments for each measurement type.
Solution Approach 2:
The patent merges two x-ray tube systems into a single integrated instrument. The two tubes are positioned to share the same sample chamber and detector system. The control system integrates the operation of both tubes, sample handling, and data processing into a unified workflow. This merging allows the system to achieve high measurement precision for both high and low concentration elements while avoiding the need for two separate instruments, thus managing device complexity.
3Measurement precision
If a monochromator is used to produce quasi mono-energetic x-rays, then the measurement precision improves for low concentration elements, but the device complexity increases
Solution Approach 1:
The monochromator acts as an intermediary component between the Molybdenum x-ray tube and the sample. It selectively transmits the Mo-Lα characteristic line (e.g., 2.293 keV) while blocking other energy components from the tube output. This intermediary function produces the desired monochromatic radiation needed for precise low concentration element measurement without requiring the tube itself to be modified. The monochromator is a standard optical component that can be integrated into existing XRF systems, thus managing the complexity increase.
4Measurement precision
If sequential measurement with multiple sources is implemented, then the measurement precision improves, but the productivity decreases due to multiple measurement steps
Solution Approach 1:
The patent implements continuous sequential measurement where the first tube completes its measurement of high concentration elements, then immediately switches to the second tube for measuring low concentration elements without interrupting the analytical workflow. The system maintains continuous engagement with the sample, and the transition between tubes is automated and rapid. This continuous action approach minimizes idle time and maintains productivity while achieving high precision through multiple specialized measurements.
Solution Approach 2:
The system employs periodic switching between the two x-ray tubes in a predetermined sequence. The first tube operates for a set duration to measure high concentration elements, then the second tube operates for a set duration to measure low concentration elements. This periodic action pattern is automated and repeatable, allowing the system to efficiently cycle through both measurement types. The periodic nature allows for optimized measurement times for each tube while maintaining overall productivity through automation.
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 enhances the reliability and accuracy of elemental concentration determination in samples by minimizing background interference, enabling the detection of low concentration elements like aluminum and silicon in the presence of high sulfur levels, and automates the process for easier operation.
Implementation Method 1
A first x-ray source directs x-rays in a first energy band at a sample
Implementation Method 2
X-ray fluorescence (XRF) is a technique used to measure the elemental composition of a sample. The sample is excited by a source of x-rays, and emits its own characteristic x-rays.
Implementation Method 3
A second x-ray source directs x-rays in a second energy band at a sample
Implementation Method 4
The sample is excited by a source of x-rays, and emits its own characteristic x-rays
Implementation Method 5
A monochromator is in the optical path between the first and/or second x-ray source and the sample
Implementation Method 6
A detector is responsive to the x-rays emitted from the sample
Data Source
AI summary
A dual source tube XRF system and method wherein a first x-ray source is employed to direct x-rays in a first energy band at a sample and at least a second x-ray source is employed to direct x-rays in a second energy band at the sample. A detector is responsive to x-rays emitted by the sample after irradiation by the first and second x-ray sources. An analyzer is responsive to the detector and is configured to determine the amount of at least a first substance in the sample based on irradiation of the sample by the first x-ray source and to determine the amount of at least a second substance in the sample based on irradiation of the sample by the second x-ray source. A controller is responsive to the analyzer and is configured to energize the first and second x-ray sources either simultaneously or sequentially.