Multi-Reflection Mass Spectrometer Non-Parallel Mirror Ion Beam Divergence
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Solution Overview
Problem
Existing multi-reflection mass spectrometers face limitations in extending ion flight path length due to beam divergence and space charge effects, which restricts mass resolution and sensitivity, particularly in time-of-flight and electrostatic trap systems.
Innovation Solution
The use of non-parallel ion-optical mirrors with varying distances and inclinations along the drift direction, combined with compensation electrodes, to control ion beam divergence and focus ions, allowing for extended flight paths without additional lenses or diaphragms, thereby enhancing mass resolution and reducing space charge interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If parallel opposing mirrors are used with elongated drift direction, then flight path length is extended, but beam divergence increases causing ion loss
Solution Approach 1:
The patent employs asymmetric mirror configurations where the opposing mirrors are not identical in shape or positioning. One mirror may be curved while the other is flat, or they may have different curvature radii. This asymmetry allows the mirrors to work together to focus ions in the drift direction while maintaining reflection functionality, thereby extending flight path without excessive beam divergence.
Solution Approach 2:
The patent utilizes curved mirror surfaces with specific curvature radii to focus ion beams. By introducing curvature to the mirror surfaces, the system achieves spatial focusing of ions in the drift direction, counteracting beam divergence while maintaining the extended flight path capability. The curvature is carefully designed to match the beam dynamics and achieve optimal focusing.
2Reliability
If multiple lenses and diaphragms are added to control beam divergence, then ion focusing improves, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into the mirror structures themselves. The mirrors simultaneously perform reflection, focusing, and spatial confinement of ions, eliminating the need for separate lenses and diaphragms. This merging of functions achieves ion beam focusing while maintaining a simple two-mirror configuration, significantly reducing device complexity compared to systems using multiple discrete optical elements.
3Speed
If gridded mirrors are used, then ion reflection is achieved, but ion flux is reduced at each reflection
Solution Approach 1:
The patent extracts the grid structure from the mirror design, transitioning from gridded mirrors to gridless mirrors. This removal of the grid eliminates the ion flux reduction problem while maintaining the ion reflection capability through purely electrostatic fields. The gridless design allows continuous ion passage without the blocking effect of grid wires, preserving ion flux while achieving the necessary reflection for extended flight paths.
4Ease of manufacture
If fixed number of mirrors is used, then manufacturing is simplified, but adaptability to different flight path lengths is reduced
Solution Approach 1:
The patent introduces adjustable parameters into the mirror system, such as variable mirror spacing, adjustable mirror angles, or controllable electrostatic field strengths. These dynamic elements allow the system to adapt to different flight path length requirements while maintaining the simple two-mirror configuration. The adjustability is achieved through mechanical or electrical control mechanisms that modify the mirror system's optical properties without adding multiple fixed mirror sets.
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 enables increased flight path length, improved mass resolution, and reduced space charge effects, allowing for more precise ion detection and analysis without the complexity of multiple lenses or diaphragms, thus enhancing the analytical capabilities of mass spectrometers.
Implementation Method 1
ions follow a zigzag flight path, reflecting between the mirrors and at the same time drifting relatively slowly along the extended length of the mirrors in the drift direction
Implementation Method 2
the mirrors are not a constant distance from each other in the X direction along at least a portion of their lengths in the drift direction
Implementation Method 3
combined with compensation electrodes, to control ion beam divergence and focus ions
Implementation Method 4
Flight path extension is desirable to increase time-of-flight separation of ions within time-of-flight (TOF) mass spectrometers
Data Source
AI summary
A multi-reflection mass spectrometer is provided comprising two ion-optical mirrors, each mirror elongated generally along a drift direction (Y), each mirror opposing the other in an X direction, the X direction being orthogonal to Y, characterized in that the mirrors are not a constant distance from each other in the X direction along at least a portion of their lengths in the drift direction. In use, ions are reflected from one opposing mirror to the other a plurality of times while drifting along the drift direction so as to follow a generally zigzag path within the mass spectrometer. The motion of ions along the drift direction is opposed by an electric field resulting from the non-constant distance of the mirrors from each other along at least a portion of their lengths in the drift direction that causes the ions to reverse their direction.