Faraday Detector Slit Configuration for Mass Spectrometer
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Solution Overview
Problem
Isotope Ratio mass spectrometers face challenges with unwanted artefacts at high resolutions, such as lost secondary electrons causing artefacts in Faraday detectors, and electron clouds forming at slit edges, which interfere with accurate detection of analytically significant peak information.
Innovation Solution
Configuring Faraday detectors with specific angles and slit shapes to minimize off-axis ion incidence and reduce secondary electron loss, and using a modified slit shape to suppress electron clouds, ensuring optimal ion transmission and detection across the focal plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high resolution analysis is performed in a mass spectrometer, then mass accuracy and discrimination capability are improved, but unwanted artefacts appear at the shoulders of peaks due to lost secondary electrons and electron cloud formation
Solution Approach 1:
The patent extracts and removes the harmful electron cloud and secondary electrons from the detection system by optimizing the slit configuration and detector positioning, thereby eliminating the artefacts they cause while maintaining high resolution mass analysis capability
Solution Approach 2:
The patent applies different slit shapes and configurations at specific locations within the mass spectrometer system - particularly at the Faraday cup entrance - to locally address the artefact problem without compromising the overall high resolution performance of the instrument
2Quantity of substance
If the Faraday detector is positioned to capture ions at the focal plane, then ion transmission is maintained, but off-axis ion incidence causes secondary electron loss and artefact formation
Solution Approach 1:
The patent changes the geometric parameters of the slit configuration - specifically using a curved or asymmetric slit shape instead of a simple rectangular opening - to control the angle of ion incidence and minimize off-axis effects while maintaining adequate ion transmission to the Faraday detector
3Ease of manufacture
If a conventional rectangular slit is used in the Faraday detector, then manufacturing is simple, but electron clouds form at the slit edges causing signal artefacts
Solution Approach 1:
The patent replaces the conventional rectangular slit with a curved or rounded slit configuration, where the edges are smoothed or rounded instead of forming sharp right angles. This curvature prevents the formation of electron clouds at the slit edges while remaining manufacturable using standard precision machining or laser cutting techniques
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
The solution eliminates artefacts caused by lost charges and electron clouds, resulting in improved high-resolution analysis with flat top peaks and enhanced detection capabilities, maintaining ion transmission and reducing interference at the shoulders of mass scans.
Implementation Method 1
Ions are spatially separated by the mass analyzer in accordance with their mass to charge ratio
Implementation Method 2
The detector chamber of the mass spectrometer is equipped with a plurality of Faraday collectors
Implementation Method 3
a high sensitivity ion counting detector (SEM)
Data Source
AI summary
A method of configuring a Faraday detector in a mass spectrometer is described. The mass spectrometer defines a central ion beam axis, and the Faraday detector is moveable relative to the central ion beam axis. The Faraday detector includes a detector arrangement having a detector surface, and a Faraday slit defining an entrance for ions into the detector arrangement. The Faraday detector has an axis of elongation which extends through the Faraday slit. A width of the Faraday slit is chosen, and the angle between the axis of elongation of the Faraday detector and the central ion beam axis is adjusted such that ions striking the detector surface do not generate secondary electrons.