Compensation Electrode Structure for Ion Trap Field Imperfections
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Solution Overview
Problem
Ion processing devices face challenges due to field imperfections caused by electrode truncation, apertures, and slots, leading to shifts in ion ejection time and mass shifts in mass spectra, which conventional methods fail to fully compensate for.
Innovation Solution
The introduction of a compensation electrode structure that communicates with or is isolated from the main electrode, positioned to compensate for field imperfections, particularly near apertures, to generate a compensated RF field that minimizes higher-order multipole effects and maintains field strength along the axis of symmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electrode structures with apertures and slots are used, then ion ejection is enabled, but field imperfections cause mass shifts and reduced mass resolution
Solution Approach 1:
A compensation electrode is introduced as an intermediary element positioned near the aperture or slot to generate compensating electric fields that counteract the harmful higher-order multipole fields generated by the aperture/slot geometry, thereby reducing mass shifts and improving mass resolution without eliminating the aperture functionality
2Productivity
If electrode apertures are introduced for ion ejection, then ion ejection efficiency improves, but higher-order multipole fields are generated causing nonlinear resonances
Solution Approach 1:
The compensation electrode utilizes the same aperture/slot geometry that generates harmful multipole fields to its advantage by positioning the compensation electrode to generate beneficial counter-fields through the same geometric features, converting the harmful effect into a useful field compensation mechanism while maintaining ion ejection efficiency
3Measurement precision
If field compensation is implemented, then mass shifts are reduced, but device complexity increases
Solution Approach 1:
The compensation electrode structure implements field compensation locally near the aperture or slot where the harmful multipole fields are generated, rather than requiring global system modifications. This localized approach reduces mass shifts while minimizing the increase in overall device complexity by confining the compensation mechanism to the specific region where it is most needed
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 mass resolution, reduces mass shifts, and improves ion ejection efficiency by eliminating nonlinear resonances and maintaining consistent field strength, thereby optimizing the performance of ion traps as mass analyzers.
Implementation Method 1
The compensation electrode structure communicates with or is isolated from the main electrode, positioned to compensate for field imperfections, particularly near apertures, to generate a compensated RF field
Implementation Method 2
The radial excursions of ions along the x-y plane may be controlled by applying a two-dimensional RF trapping field between opposing pairs of electrodes
Data Source
AI summary
An electrode structure for manipulating ions includes a main electrode and a compensation electrode. An outer surface of the main electrode includes a curved section that includes an apex. An aperture is generally disposed at the apex and extends along a radial center line from the outer surface through a thickness of the main electrode. The compensation electrode is disposed at the radial center line and at a tangent line tangent to the apex. Another electrode structure includes a plurality of main electrodes defining an interior space, and one or more compensation electrodes disposed in the interior space. RF signals may be applied to the main electrodes and to the compensation electrode.