Open Harmonized Ion Trap for Mass Spectrometer Resolution
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Solution Overview
Problem
Conventional ion cyclotron resonance mass spectrometers face limitations in achieving ultra-high resolution due to ion packet misphasing caused by differences in ion amplitudes of longitudinal oscillations, leading to reduced signal duration and resolution, despite efforts to create harmonized electric fields that are not consistently hyperbolic near trap electrodes.
Innovation Solution
An open-type dynamically harmonized ion trap is designed with a configuration of electrodes forming an open cylinder, divided by slots into central and side electrodes, where the central electrodes consist of curvilinear biangles with specific overlapping regions, and side electrodes are insulated, creating a harmonic electric field quadratic along the axis, enhancing signal duration and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ion trap geometries (cubic, closed cylindrical, or open-type cylindrical) are used, then the trap can be manufactured with simpler structures, but ion packet misphasing occurs due to non-harmonic electric fields, reducing signal duration and resolution
Solution Approach 1:
The cylindrical trap electrode is divided into multiple biangular segments arranged around the circumference. Each segment can be independently controlled, allowing the electric field to be shaped to achieve harmonic potential distribution while maintaining a manageable manufacturing complexity for each individual segment.
Solution Approach 2:
The electric field properties are optimized locally at different angular positions around the trap. By varying the potential distribution among different biangular segments, the field achieves harmonic characteristics in the critical ion confinement region while allowing non-harmonic regions near electrode surfaces where field distortions are less critical.
2Duration of action of moving object
If the number of ions in the trap is increased to enhance signal duration, then more ions are available for detection, but ion-ion interactions cause frequency shifts and phase mixing, reducing resolution
Solution Approach 1:
The trap design creates a highly harmonic electric field that produces equipotential surfaces closely matching the ideal hyperbolic potential. This uniform potential distribution minimizes variations in ion oscillation frequencies across the ion packet, reducing phase mixing effects even when ion density increases, thereby maintaining resolution while extending signal duration.
3Measurement precision
If magnetic field strength is increased to improve resolution, then cyclotron frequency increases and measurement precision improves, but the trap becomes more sensitive to field non-uniformities and ion packet misphasing
Solution Approach 1:
The electric field parameters are optimized to achieve harmonic potential distribution that is less sensitive to magnetic field variations. By adjusting the electrode potential distribution and geometry parameters, the system maintains stable ion packet phasing across a range of magnetic field strengths, enabling high-resolution measurements without excessive sensitivity to field non-uniformities.
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
The design improves the resolution and performance of the mass spectrometer by maintaining a harmonic electric field throughout the trap volume, reducing ion misphasing, and allowing deeper vacuum creation, thus increasing the maximum resolution limit at a fixed magnetic field without the need for vacuum feed-through.
Implementation Method 1
an electric field is required to confine ions, which leads to loss of synchronization of cyclotron motion
Implementation Method 2
cyclotron frequency of ion rotation in a fixed magnetic field
Implementation Method 3
frequency of ion rotation in a fixed magnetic field
Data Source
AI summary
The invention discloses design of the open-type dynamically harmonized trap directly incorporated into the body of vacuum chamber of Fourier transform ion cyclotron resonance mass analyzer. The proposed trap provides ultra-high resolution of the mass spectrometer as well as improves performance of the instrument, increases pumping rate (accelerates evacuation), eliminates necessity in vacuum feed-through, and increases maximum trap resolution limit at a fixed magnetic field.