Cylindrical Time-of-Flight Mass Spectrometer with Annular Electric Field
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Solution Overview
Problem
Conventional time-of-flight mass spectrometers face challenges in achieving high mass resolution for large biological molecules, as their mass resolution decreases with increasing ion mass, and existing solutions like zigzag flight paths increase instrument dimensions or reduce mass range.
Innovation Solution
A mass analyzer with a cylindrically-symmetric, annular electric field that causes ions to execute elliptical, angularly-precessing orbits, extending the flight path without increasing the evacuated space volume, and allowing for precise alignment without mechanical adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the physical length of the linear flight path is increased to improve mass resolution, then mass resolution is improved, but the physical dimensions of the instrument increase beyond reasonable limits
Solution Approach 1:
The patent transitions from a linear one-dimensional flight path to a two-dimensional zigzag trajectory by introducing electrostatic mirrors that reflect ions at angles. This allows the flight path to fold back on itself, effectively multiplying the path length within the same physical footprint of the instrument, thereby improving mass resolution without increasing overall instrument dimensions.
Solution Approach 2:
The zigzag flight path is nested within the existing instrument housing by using electrostatic mirrors positioned at strategic locations. The ion beam folds back through the same physical space multiple times, effectively nesting multiple reflections within the original instrument volume, thus achieving extended flight path length without external expansion.
2Measurement precision
If a zigzag flight path with multiple electrostatic mirrors is used to increase flight path length, then mass resolution is improved, but the alignment difficulty during fabrication increases
Solution Approach 1:
The patent combines multiple electrostatic mirror elements into a single integrated mirror assembly where the mirrors are pre-aligned relative to each other during manufacturing. This unified structure is then installed as one unit in the instrument, eliminating the need for complex post-fabrication alignment of multiple separate mirror components, thus reducing manufacturing difficulty while maintaining the zigzag flight path configuration.
3Length of stationary object
If the zigzag arrangement is used to decrease maximum dimensions of evacuated space, then instrument compactness is improved, but the overall volume of evacuated space may undesirably increase
Solution Approach 1:
The patent employs curved or angled mirror surfaces in the zigzag configuration that optimize the folding of the ion trajectory. The curved geometries allow the ion beam to turn sharply without requiring large radial excursions, thereby maintaining a compact overall volume of the evacuated space while still achieving the desired extended flight path length through multiple reflections.
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 provides a significantly longer flight path and higher mass resolution within a compact space, maintaining instrument dimensions while improving ion focusing and reducing ion losses.
Implementation Method 1
a cylindrically-symmetric, annular electric field to cause ions to execute a number of elliptical, angularly-precessing orbits
Implementation Method 2
The electric field provides spatial focusing to reduce ion losses and keep the beam confined regardless of the number of reflections
Data Source
AI summary
The mass spectrometer includes a mass analyzer having a pair of planar electrode structures. The electrode structures are disposed opposite one another, parallel to one another, and axially offset from one another, and are structured to generate, in response to a common pattern of voltages applied to them, a cylindrically-symmetric, annular electric field surrounding a cylindrical central region. The electric field includes an annular axially focusing lens region surrounding the central region, and an annular mirror region surrounding the lens region. Ions injected tangentially in the central region towards the electric field reach an ion detector after executing a number of ellipse-like orbits, which enables a long flight path to be accommodated within a small evacuated space.