Reflectron Ion Mirror With Toroidal Electrostatic Field
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Solution Overview
Problem
Conventional reflectron mass spectrometers and atom probe microscopes have limited angular acceptance, typically restricted to around 90°, which limits their ability to handle wide angular dispersion of ions and results in increased ion dispersion due to intersection angles with the electrostatic field grid, leading to reduced sensitivity and resolution.
Innovation Solution
A time-of-flight mass analysis device with a reflectron featuring a toroidal electrostatic field and a spherical mirror geometry, where the sample is positioned close to the center of curvature, allowing ions to be focused at a conjugate point opposite the sample, and a detector placed downstream to achieve high angular acceptance up to 180° with reduced ion dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ion mirrors with piecewise homogeneous electrostatic fields are used, then mass resolution is improved by compensating energy dispersion, but angular acceptance is limited to approximately 10°
Solution Approach 1:
The patent applies spherical symmetry to the electrostatic field configuration by positioning the sample at the center of curvature of the ion mirror. This spherical geometry allows ions emitted at wide angles (up to 180°) to be properly focused and reflected, transforming the limited angular acceptance of conventional planar mirrors into wide angular acceptance while preserving the energy dispersion compensation capability for high mass resolution
2Adaptability or versatility
If curved geometry mirrors are used to increase angular acceptance, then spatial focusing is improved, but the angular acceptance cannot exceed 90° due to geometric constraints
Solution Approach 1:
The ion mirror is designed with spherical symmetry where the sample is positioned at the center of curvature. This geometric configuration eliminates the 90° angular limitation of conventional curved mirrors by allowing ions to be emitted in any direction (up to 180°) and still be properly reflected and focused, achieving full spherical angular acceptance without additional geometric constraints
Solution Approach 2:
The patent creates an equipotential spherical surface as the reflection surface of the ion mirror. This equipotential configuration ensures that all ions, regardless of their emission angle, experience the same electrostatic potential conditions during reflection, enabling uniform focusing and time-of-flight compensation across the entire 180° angular range
3Productivity
If wide angular dispersion of ions is accepted, then sensitivity and field of view are improved, but ion dispersion increases due to intersection angles with the electrostatic field grid
Solution Approach 1:
By positioning the sample at the center of curvature of the spherical ion mirror, the patent ensures that ions emitted at any angle intersect the electrostatic field grid perpendicular to the field lines. This perpendicular intersection eliminates angular-dependent dispersion effects, allowing wide angular acceptance (up to 180°) to be achieved without increasing ion dispersion, thereby maintaining both high sensitivity and sharp spatial resolution
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 high-resolution and high-sensitivity mass analysis with wide angular acceptance, minimizing energy dispersion and spatial chromatic aberration, suitable for atom probe microscopes, and allowing for the analysis of ions with large angular dispersion without increasing detector size.
Implementation Method 1
an ion mirror producing an electrostatic field with toroidal geometry
Implementation Method 2
the sample being placed at a distance from the first center of curvature less than a quarter of the first radius of curvature
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a mass analysis device (100) with wide angular acceptance, in particular such as a mass spectrometer or an atom probe microscope, including a means for receiving a sample (101), a means for extracting ions from the surface of the sample (101), and a reflectron (103) producing a toroidal electrostatic field in which the equipotential lines are defined by a first curvature in a first direction and a first centre of curvature (105), and a second curvature in a second direction perpendicular to the first direction and a second centre of curvature, characterised in that the sample (101) is placed adjacent to the first centre of curvature (105).