Miniature Mass Spectrometer Vacuum Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional atmospheric pressure ionisation mass spectrometers are large, heavy, and power-intensive, with significant noise and heat generation, making them unsuitable for miniature applications that require high sensitivity and portability.
Innovation Solution
A miniature mass spectrometer system with a turbomolecular pump for the ion guide chamber and diaphragm pumps for foreline pumping, utilizing a short rf ion guide to efficiently transmit ions and reduce gas load, operating at pressures lower than 6.7 Pa in the ion guide chamber and higher than 6.7x10^3 Pa in other chambers, eliminating the need for bulky rotary pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large high vacuum pump is used to pump the full gas load at low pressure, then the mass analyser can operate at proper low pressure, but the system size, weight, and power consumption increase significantly
Solution Approach 1:
The pumping system is segmented into two stages: a roughing pump for initial evacuation and a high vacuum pump for maintaining low pressure. This segmentation allows each pump to be optimized for its specific pressure range, reducing the overall size and weight compared to using a single large pump capable of handling the full pressure range.
Solution Approach 2:
A roughing pump serves as an intermediary device that performs the initial evacuation to a intermediate pressure level before the high vacuum pump takes over. This intermediary step reduces the gas load on the high vacuum pump, allowing it to be smaller and lighter while still achieving the required low operating pressure.
2Productivity
If a large pump is used to achieve high gas throughput at low pressure, then atmospheric pressure ions can be efficiently drawn through the inlet, but the pump size and weight increase
Solution Approach 1:
The pumping function is segmented between a roughing pump that handles the bulk gas throughput at atmospheric pressure and a high vacuum pump that maintains low pressure. This segmentation allows the high vacuum pump to be smaller since it only needs to handle the reduced gas load after initial evacuation, while still achieving high effective throughput.
Solution Approach 2:
The system changes the pressure parameter in stages: the roughing pump operates at atmospheric pressure to maximize gas throughput, then transitions to the high vacuum pump operating at low pressure. This parameter change allows the system to achieve high throughput without requiring a single large pump to handle both pressure regimes simultaneously.
3Reliability
If conventional rotary pumps are used for vacuum pumping, then the system can achieve the required vacuum pressure, but the system becomes bulky, heavy, and noisy
Solution Approach 1:
The patent replaces conventional mechanical rotary pumps with a turbomolecular pump that uses a rotating blade mechanism operating at high speed to create vacuum. This substitution reduces mechanical complexity and eliminates the need for heavy-duty mechanical components, resulting in a more compact and lighter system while maintaining reliable vacuum pressure achievement.
Solution Approach 2:
The system changes the operational parameters by using a turbomolecular pump that operates at high rotational speeds with thin blades, rather than the low-speed heavy-duty mechanics of conventional rotary pumps. This parameter change enables the same vacuum pressure to be achieved with a much more compact and lighter device.
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 system achieves substantial reduction in size and weight while maintaining high sensitivity, enabling efficient ion transmission and collisional cooling at lower pressures, allowing for compact, lightweight, and efficient mass spectrometry.
Implementation Method 1
a vacuum chamber containing an ion guide, where a turbomolecular pump has pumped the chamber to a pressure lower than 6.7 Pa
Implementation Method 2
a diaphragm pump has pumped the foreline chamber to a pressure higher than 6.7x10^3 Pa
Implementation Method 3
the ion guide being a short rf ion guide... the ion guide is used to transmit the ion flux to the mass analyser with high efficiency
Implementation Method 4
Mass analysers are operated at low pressure to ensure that the trajectories of the ions are dominated by the applied fields rather than by collisions with neutral gas molecules
Implementation Method 5
subsequently detected by an ion detector
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A miniature mass spectrometer that may be coupled to an atmospheric pressure ionisation source is described. Ions pass through a small orifice from a region at atmospheric pressure or low vacuum, and undergo efficient collisional cooling as they transit a very short, differentially pumped ion guide. A narrow beam of low energy ions is passed through a small aperture and into a separate chamber containing the mass analyser. The apertures through which gas may escape from the ion guide have a total area less than 10cm2. The vacuum chambers containing the ion guide and the mass analyser are pumped at a pressure lower than about 6,7 Pa (5x10-2 Torr).