Annular Ion Guide Using RF Pseudo-Potential Barriers
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Solution Overview
Problem
Conventional ion guides and traps face limitations in ion confinement and capacity, leading to inefficiencies in ion transmission and analytical performance due to electric field relaxation and space charge effects, which affect the ability to apply DC voltage and maintain ion mobility separation accuracy.
Innovation Solution
The implementation of a coaxial ion guide with an annular ion guiding region, utilizing concentric or eccentric cylindrical electrodes and RF voltage barriers to create a mass-to-charge ratio dependent pseudo-potential field, allowing for improved ion confinement and increased capacity without degrading DC field application, enabling efficient ion transport and separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the radius of the aperture is increased to allow ions to occupy a larger volume, then the ion capacity is improved, but the electric field relaxation becomes more severe and the ability to apply transient DC voltage deteriorates
Solution Approach 1:
The patent transitions from a conventional circular ion guide to a toroidal (doughnut-shaped) ion guide, adding a rotational dimension to the aperture geometry. This dimensional change creates an annular aperture that increases ion capacity while maintaining effective electric field application through the unique toroidal structure
Solution Approach 2:
The toroidal aperture introduces asymmetry in the electric field distribution compared to conventional circular guides. The non-circular geometry creates distinct radial and axial field components that prevent field relaxation while accommodating larger ion populations in the expanded volume
2Productivity
If a higher transient DC voltage is applied to propel ions through the device, then ion transmission is improved, but the problem of electric field relaxation and voltage application difficulty worsens
Solution Approach 1:
The patent employs dynamic voltage application through travelling wave mechanisms that move along the ion guide structure. This dynamic approach allows efficient ion propulsion without requiring excessively high static voltages, as the moving voltage wave continuously guides ions through the toroidal path
Solution Approach 2:
The ion guide utilizes periodic voltage waveforms including travelling DC waves and RF oscillations to propel and confine ions. This periodic action replaces the need for continuously high voltage, reducing the complexity of voltage application while maintaining high ion transmission efficiency
3Ease of operation
If electric field penetration or relaxation occurs at the entrance and exit of the device, then the electric field application is simplified, but significant disruption of the electric field and loss of analytical performance worsens
Solution Approach 1:
The patent implements preliminary ion confinement using RF fields and electrostatic barriers at the entrance and exit regions before ions enter the main toroidal guiding region. This preliminary action prevents field disruption from affecting the core ion guide, maintaining analytical precision while allowing simplified field application in the main region
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 design significantly enhances ion capacity, allowing larger populations of ions to be handled with reduced space charge distortion, maintaining high analytical performance and ease of DC field application, while ensuring ions occupy the entire annular volume for optimal separation.
Implementation Method 1
utilizing concentric or eccentric cylindrical electrodes and RF voltage barriers to create a mass-to-charge ratio dependent pseudo-potential field
Implementation Method 2
The inner electrodes and/or the outer electrodes are confined by a first radial RF or pseudo-potential barrier to prevent ion movement in a radially inward direction towards the inner electrodes and a second radial RF or pseudo-potential barrier to prevent ion movement in a radially outward direction towards the outer electrodes
Implementation Method 3
The DC voltage device is arranged and adapted to apply DC voltage to urge ions along the axial length of the ion guide or ion trap
Implementation Method 4
The ion guide or ion trap preferably further comprises a device arranged and adapted to introduce a buffer gas into the annular ion guiding region in order to collisionally cool ions
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
An annular ion guide is disclosed comprising inner 5 and outer 4 electrodes. Ions are confined within an annular ion guiding region by RF or pseudo-potential barriers in both an outward and inward radial direction.