Ion Transfer Apparatus Subsonic Flow Pressure Chambers
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Solution Overview
Problem
Current ion transfer systems in mass spectrometry face inefficiencies in transferring ions from atmospheric pressure to lower pressure regions due to diffusion, space charge, and high gas velocity losses, limiting instrument sensitivity and dynamic range.
Innovation Solution
The ion transfer apparatus employs a series of pressure-controlled chambers with specific pressure ratios to maintain subsonic gas flow, combined with DC and RF focusing electrodes to guide ions effectively, reducing gas velocity and turbulence, and increasing ion transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the inlet aperture size is increased to improve ion sampling efficiency, then more ions can be sampled from the electrospray plume, but the pressure differential required for ion optical components becomes difficult to maintain and gas velocity increases causing severe ion losses
Solution Approach 1:
The single inlet aperture is segmented into multiple smaller capillaries arranged in an array. This allows the total ion sampling area to be increased while each individual capillary maintains a small enough aperture to sustain the required pressure differential. The multiple capillaries collectively sample a larger area of the electrospray plume without causing the high gas velocity and turbulent flow that would result from a single large aperture.
2Stress or pressure
If pumping speed is increased to accommodate larger inlet aperture, then pressure differential can be maintained, but the cost becomes considerable and heat transfer inefficiency and incomplete desolvation remain unresolved
Solution Approach 1:
The pumping system is segmented to serve multiple smaller capillaries rather than one large aperture. This distribution allows the pumping load to be managed more efficiently across multiple smaller pressure zones, reducing the total pumping power required compared to maintaining a single large aperture at the same pressure differential.
Solution Approach 2:
The system changes the pressure parameters across the multi-capillary array, allowing each capillary to operate at optimized pressure conditions for efficient ion transmission while collectively achieving the required overall pressure differential with reduced pumping energy.
3Speed
If pressure is reduced by two orders of magnitude in a single step through a narrow aperture, then ions can be transferred to vacuum region, but severe ion losses occur due to diffusion, space charge, and high gas velocity
Solution Approach 1:
The single large pressure step is segmented into multiple smaller pressure steps across the array of capillaries. Each capillary provides a modest pressure reduction, and the collective effect of multiple capillaries achieves the overall two-order-of-magnitude pressure reduction. This segmented approach prevents the formation of high-velocity turbulent flow and shock waves that would cause severe ion losses.
Solution Approach 2:
The pressure reduction process is extended from a single-dimensional (single aperture) to a multi-dimensional (array of capillaries) configuration. This spatial distribution allows the pressure gradient to be managed across multiple parallel pathways, reducing the velocity and turbulence in each individual pathway while maintaining the overall pressure reduction efficiency.
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 enhances ion transfer efficiency, increasing sensitivity and dynamic range by maintaining subsonic gas flow and focusing ions against the gas flow, resulting in higher ion current and lower ion losses, thereby improving mass spectrometry analysis capabilities.
Implementation Method 1
a first pressure controlled chamber at a first pressure, which first pressure is lower than 10000 Pa, and an adjacent second pressure controlled chamber at a second pressure that is lower than the first pressure
Implementation Method 2
combined with DC and RF focusing electrodes to guide ions effectively, reducing gas velocity and turbulence, and increasing ion transmission efficiency
Data Source
AI summary
An ion transfer apparatus for transferring ions from an ion source at an ion source pressure, which ion source pressure is greater than 500 mbar, along a path towards a mass analyser at a mass analyser pressure that is lower than the ion source pressure. The apparatus includes a plurality of pressure controlled chambers, wherein each pressure controlled chamber in the ion transfer apparatus includes an ion inlet opening for receiving ions from the ion source on the path and an ion outlet opening for outputting the ions on the path. The plurality of pressure controlled chambers are arranged in succession along the path from an initial pressure controlled chamber to a final pressure controlled chamber, wherein an ion outlet opening of each pressure controlled chamber other than the final pressure controlled chamber is in flow communication with the ion inlet opening of a successive adjacent pressure controlled chamber. The ion transfer apparatus is configured to have, in use, at least one pair of adjacent pressure controlled chambers for which a ratio of pressure in an upstream pressure controlled chamber to pressure in a downstream pressure controlled chamber is set such that there is substantially subsonic gas flow in the downstream pressure controlled chamber.