TOF Mass Analyzer Ion Guide Radial Confinement
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Solution Overview
Problem
The existing Time of Flight mass analyzers suffer from low ion transmission efficiency due to poor radial confinement of ions, a wide spread of initial velocities and positions leading to poor resolution, and the inability to operate with atmospheric pressure ionization sources.
Innovation Solution
A Time of Flight mass analyzer is designed with an ion guide comprising a plurality of electrodes, including multipole rod sets, ion tunnels, or planar electrodes, to radially confine ions and apply a time-varying inhomogeneous axial electric field, enhancing ion confinement and transmission efficiency while allowing operation with atmospheric pressure ionization sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a known Time of Flight mass analyser is used without radial confinement, then the device complexity is low, but the ion transmission efficiency is low
Solution Approach 1:
The mass analyser is divided into multiple functional zones along the axial direction, including an ion source region, acceleration region, drift region with radial confinement, and detection region. Each zone has specific electrodes with dedicated functions, allowing ions to be progressively guided and confined while maintaining manageable system complexity
Solution Approach 2:
Radial confinement electrodes are introduced as intermediary components between the ion source and detector. These electrodes create radial electric fields that confine ions without directly interfering with the axial time-of-flight measurement, serving as mediators that improve transmission efficiency while preserving the fundamental TOF analysis capability
2Measurement precision
If ions are allowed to travel with large spread of initial velocities and positions, then the ease of operation is high, but the measurement precision is poor
Solution Approach 1:
An acceleration region is positioned before the drift region to preliminarily accelerate ions to a standardized velocity. This preliminary acceleration action reduces the spread of initial velocities before ions enter the measurement zone, improving mass resolution without requiring complex post-acceleration adjustments
Solution Approach 2:
Different regions of the mass analyser are assigned different electric field characteristics: the acceleration region provides strong axial fields for velocity standardization, while the drift region provides radial confinement fields with minimal axial interference. This local differentiation of field qualities enables simultaneous improvement of resolution and operational simplicity
3Adaptability or versatility
If the mass analyser is designed for low pressure operation only, then the manufacturing precision requirements are lower, but the adaptability is limited
Solution Approach 1:
The radial confinement electrodes are designed to perform multiple functions: confining ions radially in the drift region, guiding ions from atmospheric pressure interfaces, and maintaining ion beams across different pressure conditions. This multi-functionality enables the mass analyser to adapt to various ion source types without requiring fundamentally different designs
Solution Approach 2:
The electric field configuration in the drift region is designed to be dynamically adjustable, allowing the radial confinement strength to be optimized for different ion source conditions and pressure regimes. This dynamic field control enables the system to adapt to varying operational requirements while maintaining consistent manufacturing tolerances
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 solution significantly improves ion transmission efficiency, enhances mass resolution, and enables operation with atmospheric pressure ionization sources, addressing the limitations of existing Time of Flight mass analyzers.
Implementation Method 1
second means arranged and adapted to apply a time varying inhomogeneous axial electric field along at least a portion of the axial length of the ion guide
Implementation Method 2
first means arranged and adapted and to confine ions radially within the ion guide
Data Source
AI summary
A mass spectrometer is disclosed comprising a time of flight mass analyzer. The time of flight mass analyzer comprises an ion guide comprising a plurality of electrodes which are interconnected by a series of resistors forming a potential divider. Ions are confined radially within the ion guide by the application of a two-phase RF voltage to the electrodes. A single phase additional RF voltage is applied across the potential divider so that an inhomogeneous pseudo-potential force is maintained along the length of the ion guide.