1D Ion Trap Extended Volume Mass Resolution
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Solution Overview
Problem
Conventional ion traps face limitations in ion capacity and mass resolution due to space charge effects, leading to degraded performance and unsuitable ion ejection methods that result in large energy spreads, making them unsuitable for coupling with other mass analyzers.
Innovation Solution
A 1D ion trap with an extended trapping volume is designed, using a combination of RF and DC voltages to confine and eject ions, allowing for mass-to-charge ratio selective ejection with low energy spread, and is capable of holding a higher ion charge capacity than conventional 3D and 2D ion traps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional 3D ion traps are used to confine ions, then ions are confined to a single point in space, but the ion storage capacity is limited due to space charge effects and mutual repulsion between ions
Solution Approach 1:
The patent transitions from a 3D ion trap that confines ions to a single point to a 2D linear ion trap that confines ions along a linear region. This dimensional change allows ions to be distributed over a longer axial distance, reducing space charge effects and enabling higher ion storage capacity while maintaining mass resolution through extended trapping volume
2Quantity of substance
If more ions are confined in the ion trap to increase ion capacity, then the number of confined charges increases, but the electric field becomes distorted leading to loss of mass resolution and mass accuracy
Solution Approach 1:
The ion trap is segmented into multiple rod electrodes (typically four rods) arranged in a linear configuration, creating a 2D trapping region. This segmentation allows the ion cloud to be distributed along the axial direction rather than concentrated at a single point, reducing electric field distortion from space charge effects while maintaining sufficient field uniformity for accurate mass measurement
3Productivity
If resonant excitation is used to eject ions from the trap, then ions can be ejected in a mass selective manner, but the ejection process is non-adiabatic resulting in large energy spreads that make coupling with other mass analyzers difficult
Solution Approach 1:
The patent applies periodic RF voltages to the rod electrodes to create a time-varying potential that adiabatically accelerates ions along the trap axis. This periodic action allows ions to be ejected with controlled, low energy spreads while maintaining mass selectivity, enabling efficient coupling with downstream mass analyzers such as time-of-flight analyzers
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 1D ion trap significantly increases ion storage capacity and maintains high mass resolution even at higher ion charges, enabling efficient ion ejection with minimal space charge effects, thus improving the performance of mass spectrometry systems.
Implementation Method 1
A pseudo-potential well is formed within the rod set ion trap around the central axis of the ion guide so that ions are confined radially within the ion trap
Implementation Method 2
The ions are normally confined axially using DC fields
Implementation Method 3
a supplemental AC voltage is applied to the rod electrodes having a frequency which is equal to the fundamental or resonance frequency of those ions which are desired to be ejected from the trap
Data Source
Figure 1A~1F
Figure 2A~2C
Figure 3A~3C
AI summary
A mass or mass to charge ratio selective ion trap is disclosed having an increased charge storage capacity. A RF voltage acts to confine ions in a first (y) direction within the ion trap. A DC voltage and/or an RF voltage acts to confine ions in a second (x) direction within the ion trap. A quadratic DC potential well acts to confine ions in a third (z) direction within the ion trap. Ions are excited in the third (z) direction and are caused to be mass or mass to charge ratio selectively ejected in the third (z) direction.