Gastight RF Ion Guide Layout for Compact Mass Spectrometers
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Solution Overview
Problem
Existing mass spectrometers face challenges with conflicting vacuum requirements between collision cells and mass analyzers, leading to oversized designs, inefficient pumping systems, and ion transmission losses due to restrictive apertures, which hinder the development of compact, cost-effective instruments.
Innovation Solution
The design separates ion source and collision-cooling ion guide regions from mass analyzers, allowing them to be pumped efficiently with smaller turbo pumps, and uses gastight radio frequency ion guides that operate at standard atmospheric pressures, reducing pumping volumes and enabling smaller, more cost-effective mass spectrometer systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If collision cell and mass analyzer are placed in the same vacuum chamber, then vacuum requirements can be met, but system size and pumping requirements increase unnecessarily
Solution Approach 1:
The invention divides the vacuum system into two separate chambers: a first vacuum chamber containing the collision cell and a second vacuum chamber containing the mass analyzer. This segmentation allows each chamber to be optimized independently for its specific vacuum requirements, reducing the total vacuum volume that needs to be pumped while maintaining reliable operation in both regions.
2Device complexity
If single turbo-molecular pump is used to evacuate both ion source and analyzer regions, then pump count is reduced, but pumping efficiency decreases due to distant placement from one region
Solution Approach 1:
The invention assigns different pumping responsibilities to different stages of the turbo-molecular pump: the interstage evacuates the ion source region while the upper stage evacuates the analyzer region. This segmentation of pumping functions allows both regions to be efficiently evacuated despite using a single pump, as each stage is optimally positioned for its designated region.
3Reliability
If restrictive apertures are used to limit gas outflow between pumping regions, then vacuum isolation is improved, but ion transmission efficiency decreases
Solution Approach 1:
The invention introduces a differential pumping region with a defined volume between the ion source region and the analyzer region. This intermediary volume acts as a buffer that allows gas to flow from the ion source without directly impacting the analyzer vacuum, thereby maintaining vacuum isolation while avoiding the need for restrictive apertures that would impede ion transmission.
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 minimizes pumping requirements, reduces system size and weight, enhances ion transmission efficiency, and allows for more flexible instrument layouts while maintaining reliable operation within critical temperature specifications.
Implementation Method 1
a substantially gastight (and possibly gas-supplied) radio frequency ion guide, such as a tubular multipole ion guide, having a multipole configuration
Implementation Method 2
an upper stage of the turbo-molecular pump is used to evacuate the analyzer region
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5B
AI summary
The disclosure relates to a mass spectrometer, comprising (a) a vacuum recipient containing ion handling elements of the mass spectrometer, the vacuum recipient having a plurality of walls which define a gastight volume and comprise at least one of an entrance and exit, wherein different portions of an ion path pass at least one of the entrance and exit and run through the gastight volume; and (b) a gastight radio frequency ion guide having an ion passage along an axis and being mounted gastight to at least one of the entrance and exit as to continue the ion path in its ion passage outside the gastight volume. Embodiments of the disclosure facilitate, in particular, reducing pumping volumes in the mass spectrometer and corresponding pumping requirements as well as lowering the size and weight of such an assembly.