Multipole Ion Focusing Through a Low-Barrier Central Aperture
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Solution Overview
Problem
Current ion guides, such as RF carpets and ion funnels, face challenges in efficiently guiding ions through high-pressure gas environments due to unbalanced RF fields and pseudopotential barriers, leading to ion scattering and reduced transmittance, especially for low m/z ions, which complicates the integration with downstream devices and requires complex fabrication processes.
Innovation Solution
The design incorporates an ion focusing device with a multipole ion guide and an ion collection element, where curved electrodes receive the same phase RF signals, and adjacent electrodes are out of phase, creating a symmetrical electric field that minimizes pseudopotential barriers, allowing for improved ion transmittance through a miniature central aperture by aligning the multipole ion guide closely with the ion collection element, and applying a DC offset for efficient ion guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If concentric-ring ion carpets are used to focus ions at a border between regions of different pressures, then ion focusing capability is improved, but device complexity increases due to requiring at least two layers of PCB fabrication and multiple vias
Solution Approach 1:
The ion guide structure is divided into multiple discrete ring electrodes with different geometries (inner radius, outer radius, spacing) that can be independently designed and optimized. Each ring electrode acts as an independent functional unit contributing to the overall ion focusing capability while allowing simplified single-layer PCB fabrication
Solution Approach 2:
The patent transitions from complex multi-layer PCB structures with vertical vias to a single-layer planar structure where ion focusing is achieved through carefully designed two-dimensional electrode patterns. The ion guiding function is maintained by optimizing the radial and axial dimensions of the ring electrodes in the planar configuration
2Object-affected harmful factors
If features are made as small as possible to avoid unwanted ion scattering, then ion scattering is reduced, but fabrication complexity increases
Solution Approach 1:
The patent optimizes key geometric parameters of the ring electrodes including inner radius, outer radius, radial spacing, and axial positioning to achieve effective ion focusing while maintaining features that are manufacturable with standard PCB technologies. The parameters are tuned to balance ion scattering reduction with fabrication ease
3Reliability
If RF field amplitude is increased to keep ions away from substrate material, then ion guidance reliability is improved, but pseudopotential barriers increase that may prevent ions from penetrating the aperture
Solution Approach 1:
Different regions of the ion guide structure have different electrode configurations optimized for their local functions. The inner rings have different dimensions and spacing compared to outer rings, creating locally optimized electric field distributions that provide strong ion confinement where needed while maintaining low pseudopotential barriers at the aperture region for efficient ion transmission
4Productivity
If DC field is applied to drive ions in a desired direction, then ion transport efficiency is improved, but ion scattering increases when ions move close to aperture edges
Solution Approach 1:
The patent applies DC offsets to specific ring electrodes to create a smooth axial potential gradient that drives ions through the structure. The equipotential surfaces are shaped by the ring electrode geometry to guide ions along the central axis, keeping them away from aperture edges and reducing scattering while maintaining efficient transport
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 enhances ion transmittance and reduces losses by eliminating pseudopotential barriers, allowing for a tighter ion beam focus and improved coupling with downstream devices, while simplifying the fabrication process and maintaining high-purity conditions.
Implementation Method 1
the electrodes are closely spaced (typical dimensions are around 1 mm or less). This achieves a sufficiently strong RF electric field that keeps ions away from the material of the substrate or other supporting components
Implementation Method 2
The electrodes are often biased to generate a DC field that drives the ions in a desired direction towards and along the structure
Implementation Method 3
unbalanced RF fields and pseudopotential barriers, leading to ion scattering and reduced transmittance
Data Source
AI summary
An ion focusing device comprising an ion collection element comprising a plurality of N curved electrodes extending around an axis of the ion collection element and an aperture on an axis of the ion collection element. A multipole ion guide adjacent the ion collection element and having a plurality of N elongate electrodes extending parallel to and around an axis of the multipole ion guide, wherein the axis of the multipole ion guide coincides with the axis of the ion collection element, wherein each of the N curved electrodes of the ion collection element are configured to receive a radio frequency, RF, signal having the same phase as an RF signal configured to be applied to at least one elongate electrode of the plurality of elongate electrodes of the multipole ion guide, and further wherein at least two of the N electrodes of the ion collection element are configured to receive RF signals of a different phase.