Ion Guide Quadrupolar Field Mass Range
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current time-of-flight mass spectrometers face limitations in ion beam confinement and mass range due to the use of RF fields, which restrict the retained mass range and introduce mass-dependent and RF phase-dependent effects during ion pulsed ejection, while static quadrupolar fields only allow for moderate elongation and suffer from ion beam defocusing.
Innovation Solution
A pulsed ion accelerator with a spatially varying DC electrostatic field is employed, using a quadrupolar field configuration that alternates along the orthogonal direction, allowing for ion confinement independent of mass-to-charge ratios and enabling longer ion guide lengths with reduced ion losses and surface charging, without the need for resonant RF circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF fields are used for ion beam confinement, then ion confinement is achieved, but mass range is restricted and mass-dependent effects are introduced
Solution Approach 1:
The patent changes the fundamental parameter of the confining field from RF (radio frequency) to static quadrupolar DC field. This parameter change eliminates mass-dependent effects and extends the usable mass range while maintaining ion confinement capability through the quadrupolar field configuration.
Solution Approach 2:
The patent substitutes the RF electromagnetic field system with a static electric field system. By replacing the time-varying RF field with a static quadrupolar DC field, the system achieves ion confinement without the mass-dependent effects inherent in RF-based confinement.
2Adaptability or versatility
If static quadrupolar field is used for ion confinement, then mass range is extended, but ion beam defocusing occurs
Solution Approach 1:
The patent segments the static quadrupolar field into multiple sections along the ion beam path, with alternating polarities. This segmentation creates a series of focusing and defocusing regions that collectively maintain ion beam focus while extending the mass range, preventing the defocusing problem of uniform static fields.
Solution Approach 2:
The patent implements periodic alternation of the quadrupolar field polarity along the ion guide. This periodic action creates alternating focusing and defocusing sections that, when properly designed, result in net focusing of the ion beam while maintaining the mass-independent confinement advantage of static fields.
3Measurement precision
If ion guide length is increased for higher resolution, then mass accuracy is improved, but ion losses and surface charging increase
Solution Approach 1:
The patent introduces a carefully designed static quadrupolar field as an intermediary mechanism between the ion source and detector. This field configuration provides gentle, mass-independent confinement that reduces ion losses to walls and minimizes surface charging effects, enabling longer ion guide lengths for higher resolution without the penalty of increased ion losses.
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 solution provides improved ion confinement and reduced micro-motion, enabling higher mass range analysis with reduced angular and spatial spreads, and enhances the coupling of elongated pulsed converters with multi-reflecting TOF and electrostatic trap mass spectrometers for increased sensitivity and duty cycles.
Implementation Method 1
an ion guide portion having electrodes arranged to receive ions travelling along a first direction (Z-dimension), including a plurality of DC electrodes spaced along the first direction; DC voltage supplies configured to apply different DC potentials to different ones of said DC electrodes such that when ions travel through the ion guide portion along the first direction they experience an ion confining force, generated by the DC potentials, in at least one dimension (X- or Y-dimension) orthogonal to the first direction
Implementation Method 2
a pulsed voltage supply configured to apply a pulsed voltage to at least one electrode of the ion accelerator for pulsing ions out of the ion accelerator in a second direction (X-dimension) substantially orthogonal to the first direction (Z-dimension)
Data Source
AI summary
Elongation of orthogonal accelerators is assisted by ion spatial transverse confinement within novel confinement means, formed by spatial alternation of electrostatic quadrupolar field (22). Contrary to prior art RF confinement means, the static means provide mass independent confinement and may be readily switched. Spatial confinement defines ion beam (29) position, prevents surfaces charging, assists forming wedge and bend fields, and allows axial fields in the region of pulsed ion extraction, this way improving the ion beam admission at higher energies and the spatial focusing of ion packets in multi-reflecting, multi-turn and singly reflecting TOF MS or electrostatic traps.