Miniature Mass Spectrometer Split Flow Pump Design
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Solution Overview
Problem
Conventional mass spectrometers face challenges in operating at atmospheric pressure due to the need for small orifices, which restricts ion transmission and sensitivity, and require large, heavy vacuum pumps, making them impractical for compact or miniature designs.
Innovation Solution
A miniature mass spectrometer design with a split flow turbomolecular vacuum pump and a single backing vacuum pump, utilizing smaller pumps with lower pumping speeds, and incorporating RF ion guides within the first vacuum chamber to maintain high pressure and facilitate ion transmission while reducing the number of pumps and overall size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single orifice is used to transfer ions from atmospheric pressure to vacuum chamber, then the structure is simple, but the ion transmission is very low severely restricting sensitivity
Solution Approach 1:
The vacuum system is divided into multiple differential pumping stages (first, second, and third vacuum chambers) with intermediate orifices between them. This segmentation allows each stage to handle pressure reduction incrementally, enabling larger cumulative orifice areas while maintaining adequate vacuum levels for mass analysis.
Solution Approach 2:
The patent transitions from a single-orifice one-dimensional solution to a multi-stage three-dimensional vacuum architecture. By adding spatial dimensions (multiple chambers stacked in series), the system achieves both high ion transmission and adequate vacuum quality simultaneously.
2Manufacturing precision
If the atmospheric pressure orifice is made large to increase ion transmission, then sensitivity improves, but an impractically large vacuum pump is required
Solution Approach 1:
The total gas throughput is distributed across multiple differential pumping stages. Each stage handles a portion of the gas load, allowing the use of smaller vacuum pumps with lower pumping speeds while still achieving the required vacuum levels for mass analysis.
Solution Approach 2:
The patent employs dynamic pressure management across multiple stages, where each chamber operates at a different pressure level. This dynamic approach allows optimization of orifice sizes and pump capacities at each stage, reducing the overall pump size requirement compared to a single-stage system.
3Manufacturing precision
If multiple stages of differential pumping are used to reduce pressure in stages, then ion transmission improves, but the device complexity and size increase
Solution Approach 1:
The patent combines multiple vacuum chambers and pumping functions into an integrated compact architecture. The first vacuum pump serves dual purposes by backing both the first stage and the turbomolecular pump, reducing the total number of independent pump components while maintaining multi-stage differential pumping functionality.
Solution Approach 2:
The vacuum chambers are arranged in a nested or cascaded configuration where the first vacuum chamber contains or is connected to the second, which contains or is connected to the third. This nesting allows compact packaging of multiple differential pumping stages in a reduced overall footprint.
4Reliability
If conventional vacuum pumps with large pumping speeds are used, then adequate vacuum is maintained, but the mass spectrometer size and weight increase making it non-compact
Solution Approach 1:
The vacuum system is segmented into multiple stages with progressively lower pumping speeds required at each stage. The first stage handles atmospheric pressure reduction with a small pump, while subsequent stages use turbomolecular pumps with intermediate speeds, eliminating the need for a single large high-speed pump.
Solution Approach 2:
The patent replaces conventional single-stage mechanical vacuum pumping with a hybrid system combining a small mechanical pump (first vacuum pump) with a turbomolecular pump (non-mechanical momentum transfer pumping). This substitution enables compact design while maintaining adequate vacuum quality for mass analysis.
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 design achieves a compact, lightweight mass spectrometer with improved sensitivity and reduced power consumption, maintaining sensitivity comparable to full-size instruments while significantly reducing size and weight.
Implementation Method 1
a split flow turbomolecular vacuum pump which has an intermediate pumping port and a high vacuum pumping port; wherein the intermediate pumping port is connected to the second vacuum chamber and the high vacuum pumping port is connected to the third vacuum chamber
Implementation Method 2
wherein the first vacuum pump is also arranged and adapted to act as a backing vacuum pump to the split flow turbomolecular vacuum pump
Implementation Method 3
a first RF ion guide located within the first vacuum chamber
Data Source
AI summary
A miniature mass spectrometer is disclosed comprising an atmospheric pressure ionization source 701, a first vacuum chamber having an atmospheric pressure sampling orifice or capillary, a second vacuum chamber located downstream of the first vacuum chamber and a third vacuum chamber located downstream of the second vacuum chamber. A first vacuum pump 707 is arranged and adapted to pump the first vacuum chamber, wherein the first vacuum pump 707 is arranged and adapted to maintain the first vacuum chamber at a pressure <10 mbar. A first RF ion guide 702 is located within the first vacuum chamber. An ion detector 705 is located in the third vacuum chamber. The ion path length from the atmospheric pressure sampling orifice or capillary to an ion detecting surface of the ion detector 705 is ≤400 mm. The mass spectrometer further comprises a split flow turbomolecular vacuum pump 706 comprising an intermediate or interstage port connected to the second vacuum chamber and a high vacuum (“HV”) port connected to the third vacuum chamber. The first vacuum pump 707 is also arranged and adapted to act as a backing vacuum pump to the split flow turbomolecular vacuum pump 706. The first vacuum pump has a maximum pumping speed ≤10 m3/hr (2.78 L/s).