Mass Spectrometer Differential Pumping Ion Source
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Solution Overview
Problem
Existing mass spectrometers face challenges in achieving highly accurate mass spectroscopy while being compact and lightweight, as intermittent introduction of ionized samples leads to increased loss during transport and requires efficient ionization to maintain high vacuum conditions.
Innovation Solution
A mass spectrometer design that incorporates a differential pumping scheme to reduce the pressure in the ion source from atmospheric to 100 Pa to 10,000 Pa and then to 0.1 Pa or lower in the mass spectroscopy section, using a dielectric barrier discharge for efficient ionization and minimizing transport loss by controlling the pulse valve operation to optimize pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If intermittent introduction of ionized samples is used to maintain high vacuum, then the mass spectroscopy section can be kept at high vacuum with a small-sized vacuum pump, but transport loss of ionized samples increases
Solution Approach 1:
The system uses periodic opening and closing of the pulse valve to control intermittent introduction of ionized samples into the mass spectroscopy section. This periodic action allows the vacuum pump to maintain high vacuum during closed periods while permitting sample introduction during open periods, resolving the contradiction between pump size and sample transport efficiency
Solution Approach 2:
The system changes pressure parameters dynamically by controlling the pulse valve timing. The ion source pressure is raised to 100-10,000 Pa during gas inhalation for efficient ionization, then the mass spectroscopy section pressure is maintained at 0.1 Pa or lower. This parameter change optimizes both ionization efficiency and vacuum maintenance
2Loss of substance
If continuous introduction with differential pumping is used, then transport loss of ionized samples is minimized, but the mass spectroscopy section cannot maintain high vacuum environment
Solution Approach 1:
The pulse valve operates periodically to open for brief intervals during which ionized samples are rapidly transported to the mass spectroscopy section, then closes to allow the vacuum system to restore high vacuum conditions. This periodic cycling minimizes transport loss while maintaining the high vacuum environment necessary for accurate mass spectroscopy measurements
3Productivity
If ionization is performed at atmospheric pressure, then ionization efficiency is high, but the pressure in the mass spectroscopy section cannot be maintained at high vacuum
Solution Approach 1:
The system creates different pressure conditions in different spatial zones: the ion source region operates at elevated pressure (100-10,000 Pa) to enable efficient ionization, while the mass spectroscopy section is maintained at high vacuum (0.1 Pa or lower). The pulse valve and differential pumping system manage the transition between these zones, allowing each region to have optimal local conditions for its specific function
Solution Approach 2:
The mass spectrometer is segmented into distinct pressure zones: an ion source region where gas is introduced and ionized at elevated pressure, and a mass spectroscopy region maintained at high vacuum. The pulse valve controls the interface between these segments, allowing efficient ionization in one segment while preserving vacuum conditions in the other segment for accurate measurement
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
Enables highly accurate mass spectroscopy with reduced size and weight by minimizing ion loss during transport and ensuring efficient ionization, allowing for repetitive measurements in a high vacuum environment.
Implementation Method 1
ionization schemes utilizing dielectric barrier discharge phenomena have been proposed as ionization schemes capable of highly efficient ionization
Implementation Method 2
a differential pumping scheme has been proposed as shown in U.S. Pat. No. 7,592,589
Data Source
AI summary
A mass spectrometer of reduced size and weight is provided which is capable to conduct highly accurate mass spectroscopy. The mass spectrometer includes an ion source adapted to ionize gas flowing in from outside in order to ionize a measurement sample and a mass spectroscopy section for separating the ionized measurement sample. The ion source has its interior reduced in pressure by differential pumping from the mass spectroscopy section and ionizes the gas when the interior pressure rises as it inhales the gas, and the mass spectroscopy section separates the ionized measurement sample when its interior pressure falls after inhale of the gas. The mass spectrometer may further include a restriction device for suppressing a flow rate of the gas the ion source inhales and an open/close device for opening and closing a flow of the gas the ion source inhales.