Jet Injector Inlet for DMS Ion Loss Reduction
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Solution Overview
Problem
Ion losses occur during introduction in Differential Mobility Spectrometers (DMS) due to fringing electric fields, affecting ion transmission efficiency and causing discrimination between ions with high and low mobility coefficients.
Innovation Solution
Implementing a fast ion injection method using a gas beam jet to promptly inject ions into the DMS cell and pre-focusing ions with an additional focusing RF electric field, reducing residence time in detrimental fringing electric field regions, and optionally using a shielding electrode to minimize these effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ions are introduced into the DMS analytical gap using conventional methods, then ion separation can be performed, but ion losses occur due to fringing electric fields reducing transmission efficiency
Solution Approach 1:
A jet injector electrode is introduced as an intermediary component between the ion source and the DMS analytical gap. This electrode forms a gas beam jet that serves as a mediator to transport ions through the fringing electric field region, shielding them from the harmful effects of the asymmetric RF and DC fields while maintaining ion transmission efficiency
Solution Approach 2:
The jet injector electrode creates a focused gas beam jet that rapidly transports ions through the detrimental fringing electric field region. By rushing ions through this region quickly, the residence time in the harmful field is minimized, reducing ion losses before ions enter the main analytical gap
2Measurement precision
If the cross-sectional area of the jet injector electrode aperture is reduced, then ion focusing improves, but gas flow rate decreases
Solution Approach 1:
The system optimizes the aperture dimensions of the jet injector electrode to achieve the right balance between ion focusing and gas flow rate. By carefully selecting the aperture size parameter, the design maintains sufficient gas flow to carry ions while providing adequate focusing to improve ion trajectory control and reduce losses in the fringing field 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 approach significantly enhances ion transmission through the analytical gap by reducing the impact of fringing electric fields, improving ion injection efficiency and maintaining ion trajectories, thereby increasing signal quality and reducing signal loss.
Implementation Method 1
a gas beam jet which promptly injects ions into the inlet of the DMS cell
Implementation Method 2
Pre-focusing ions in the area before the entrance (in areas where the fringing electric field is active) and focus them towards the central axis of the analytical gap. In this embodiment ion introduction occurs due to the harmonic superimposed effects of an additional focusing RF electric field
Implementation Method 3
The gas beam or jet can be directed into the central axis of the DMS cell to ensure that targeted ion species are substantially removed from insulating surfaces at the front of the DMS slot
Data Source
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AI summary
A method and apparatus for performing differential mobility spectrometer (DMS) which includes decreasing the amount of time that ions spend inside fringing fields generated by the DMS. The apparatus includes an entrance electrode plate sealingly engaged to the entrance of the DMS, and is electrically separated from the parallel plate electrodes of the DMS, the entrance electrode plate has an aperture for allowing the traversal of ions into the DMS; wherein the cross- sectional area of the aperture is less than the cross-sectional area of the ion path, the ion path being located between the two parallel plate electrodes of the DMS. The entrance electrode plate may also have a focusing potential applied to it for focusing of ions.