Mass Spectrometer Three-Stage Vacuum System
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Solution Overview
Problem
Traditional mass spectrometers face challenges in balancing sensitivity and miniaturization due to the need for high pumping speed at low pressures, which complicates the pump system and increases size, while also limiting gas flow and ion transfer.
Innovation Solution
A mass spectrometer design with a three-stage vacuum system, where the first vacuum chamber operates at a high pressure (>30 mbar) with a roughing pump, the second at 0.5-30 mbar with a roughing pump, and the third at low pressure, using a turbo molecular pump, allowing for high gas flow and compact pump system without direct atmospheric pressure interface, facilitating ion focusing and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sample introduction interface is made very small to directly transfer ions from atmospheric pressure to vacuum chamber, then the pump system can be miniaturized, but the number of ions transferred is significantly reduced, limiting the sensitivity of the instrument
Solution Approach 1:
The vacuum system is divided into multiple stages: a first vacuum chamber at relatively high vacuum (10^-3 to 10^-6 mbar) and a second vacuum chamber at ultra-high vacuum (10^-6 to 10^-9 mbar). This segmentation allows the sample introduction interface to be larger for high ion transfer efficiency, while the second stage provides the necessary vacuum for mass analysis with a smaller pump system.
Solution Approach 2:
The first vacuum chamber acts as an intermediary between the atmospheric pressure environment and the ultra-high vacuum second chamber. It serves as a transition zone that allows efficient ion transfer from the source while protecting the second vacuum chamber from excessive gas load, enabling the use of a smaller pump in the second stage.
2Quantity of substance
If a pump with relatively high pumping speed is used to achieve high gas flow rate at relatively low pressure, then the sensitivity is improved, but the pump size becomes relatively large, which is not conducive to miniaturization of the mass spectrometer
Solution Approach 1:
The pumping system is segmented into two stages with different pumping speed requirements. The first vacuum chamber uses a pump with moderate pumping speed to maintain relatively high vacuum, while the second chamber uses a smaller pump to achieve ultra-high vacuum. This segmentation allows high gas flow handling without requiring a single large pump.
Solution Approach 2:
The first vacuum chamber serves as an intermediary that handles the bulk gas removal task, allowing the second vacuum chamber to use a smaller pump with lower pumping speed requirements while still achieving the necessary ultra-high vacuum for sensitive mass analysis.
3Reliability
If a three-stage vacuum structure with two turbo molecular pumps and two diaphragm pumps is used, then the vacuum requirements are met, but the pump system becomes relatively complicated and costs high
Solution Approach 1:
The invention extracts and eliminates the need for a third vacuum stage and its associated pump from the system. By optimizing the two-stage configuration with the first chamber operating at relatively high vacuum, the complex three-stage structure with multiple turbo and diaphragm pumps is simplified to a more manageable two-stage system.
Solution Approach 2:
The first vacuum chamber is designed to perform multiple functions: it maintains vacuum for the ion source, facilitates efficient ion transfer, and protects the second ultra-high vacuum chamber from excessive gas load. This multi-functionality reduces the need for additional specialized vacuum stages and pumps.
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 design achieves high sensitivity and miniaturization by optimizing gas flow and pressure conditions, reducing pump size and cost, and ensuring stable ion transmission, while maintaining operational stability for high-vacuum apparatuses like mass analyzers.
Implementation Method 1
the range of working pressure P1 of the first vacuum chamber being P1>30 mbar
Implementation Method 2
the range of working pressure P2 of the second vacuum chamber being 0.5 mbar≤P2≤30 mbar
Implementation Method 3
a third vacuum chamber, which is connected to the second vacuum chamber by means of a vacuum interface to receive analyte from the second vacuum chamber, and is connected to a third vacuum pump
Data Source
AI summary
A mass spectrometer includes a first vacuum chamber, which is provided with an atmospheric pressure interface communicating with an external atmospheric pressure environment and to a first vacuum pump, the range of working pressure P1 of the first vacuum chamber being P1>30 mbar; a second vacuum chamber, which is connected to the first vacuum chamber by means of a vacuum interface to receive the analyte from the first vacuum chamber and to a second vacuum pump, the range of working pressure P2 of the second vacuum chamber being 0.5 mbar≤P2≤30 mbar; and a third vacuum chamber, which is connected to the second vacuum chamber by means of a vacuum interface to receive the analyte from the second vacuum chamber and to a third vacuum pump, the first vacuum pump or the second vacuum pump being used as a forepump of the third vacuum pump.