Multi-electrode Ion Trap Field Correction
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Solution Overview
Problem
The Orbitrap mass spectrometer and other electrostatic ion traps face challenges in achieving high performance due to imperfections in electrode shape and position, leading to non-linearities in the trapping field, which affect mass accuracy, resolution, and peak intensity.
Innovation Solution
A method is developed to operate an electrostatic ion trapping device using an array of electrodes to mimic a single electrode, determining and applying multiple voltages to correct imperfections, thereby approximating a hyper-logarithmic trapping field, and iteratively optimizing these voltages based on measured characteristics to ensure better trapping field quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single electrode is used to create the trapping field, then the device structure is simple, but manufacturing imperfections cause non-linearities that degrade mass accuracy and resolution
Solution Approach 1:
The single electrode is divided into multiple segments (first, second, third, and fourth electrodes) arranged in a multi-electrode configuration. This segmentation allows independent voltage control of each electrode to compensate for manufacturing imperfections and achieve a more accurate hyper-logarithmic trapping field, thereby improving mass accuracy while maintaining structural feasibility.
2Measurement precision
If electrode shapes are perfected to eliminate non-linearities, then mass accuracy improves, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of requiring perfect electrode shapes, the invention changes the electrical parameters (voltages) applied to each electrode segment. By independently adjusting the voltages on the four electrodes, the system compensates for shape imperfections and achieves the desired hyper-logarithmic trapping field, improving mass accuracy without increasing manufacturing complexity.
3Reliability
If multiple voltages are applied to correct electrode imperfections, then trapping field quality improves, but device complexity increases
Solution Approach 1:
The electrode system is segmented into four independently controllable electrodes, allowing application of different voltages to each segment. This segmentation enables precise control of the trapping field to compensate for imperfections, improving reliability while keeping the control system manageable through modular voltage application.
4Measurement precision
If high precision electrode manufacturing is implemented, then resolution improves, but manufacturing time and cost increase
Solution Approach 1:
The invention shifts from requiring high-precision mechanical manufacturing of electrode shapes to using electrical parameter adjustments (voltages) to achieve the desired field quality. This parameter change approach maintains high resolution while significantly improving manufacturing efficiency, as voltage control is faster and more flexible than precision machining.
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 improves the quality of the trapping field, maintaining coherence of ion oscillations and enhancing mass spectra by compensating for electrode imperfections, thus achieving better mass accuracy and resolution across a wide range of peak intensities.
Implementation Method 1
determining three or more different voltages that, when applied to respective electrodes of the plurality of electrodes, generate an electrostatic trapping field that approximates the field that would be generated by applying a voltage to the single electrode
Implementation Method 2
the frequency of the axial oscillations is related only to the mass to charge ratio (m/z) of ions as: where T is the frequency of oscillation and k is a constant
Data Source
AI summary
This invention relates generally to multi-reflection electrostatic systems, and more particularly to improvements in and relating to the Orbitrap electrostatic ion trap. A method of operating an electrostatic ion trapping device having an array of electrodes operable to mimic a single electrode is proposed, the method comprising determining three or more different voltages that, when applied to respective electrodes of the plurality of electrodes, generate an electrostatic trapping field that approximates the field that would be generated by applying a voltage to the single electrode, and applying the three or more so determined voltages to the respective electrodes. Further improvements lie in measuring a plurality of features from peaks with different intensities from one or more collected mass spectra to derive characteristics, and using the measured characteristics to improve the voltages to be applied to the plurality of electrodes.