Ionizer Electron Beam Passage Opening Design
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Solution Overview
Problem
Mass spectrometers face challenges in improving measurement sensitivity due to the limitations of existing ionizers, where reducing the size of electron beam passage openings or the ion outlet to increase sample gas density either decreases the electron beam incidence or the ion emission, hindering sensitivity enhancement.
Innovation Solution
The ionizer design features electron beam passage openings with a length greater than the width of their cross-sectional shape, reducing molecular flow conductance and increasing sample gas density within the ionization chamber without decreasing electron beam incidence, thereby enhancing ion generation and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of electron beam passage openings or ion outlet is reduced to increase sample gas density, then the number density of molecules in the ionization chamber increases, but the amount of electron beam incident or ion discharged decreases
Solution Approach 1:
The electron beam passage opening is designed with a needle-like shape where the length in the electron beam incident direction is significantly longer than the width of the cross-section orthogonal to this direction. This dimensional change allows the opening to have small cross-sectional area (reducing molecular flow conductance) while maintaining sufficient length to allow adequate electron beam incidence, thereby resolving the contradiction between increasing molecule density and maintaining beam incidence amount.
2Quantity of substance
If the ion outlet is made smaller to increase number density of molecules, then the number density of molecules in the ionization chamber increases, but the amount of ions discharged decreases
Solution Approach 1:
The ion outlet is designed with a needle-like shape where the length in the ion discharge direction is significantly longer than the width of the cross-section orthogonal to this direction. This dimensional change allows the outlet to have small cross-sectional area (increasing molecule density in the chamber) while maintaining sufficient length to ensure adequate ion discharge, thereby resolving the contradiction between increasing molecule density and maintaining ion discharge amount.
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 configuration increases the number density of sample gas molecules and the amount of generated ions, leading to improved measurement sensitivity in mass spectrometers.
Implementation Method 1
molecules of sample gas existing in the ionization chamber 110 are irradiated with an electron beam to generate ions
Implementation Method 2
a predetermined current is supplied to one filament 111 to generate thermions, which are emitted toward the other filament 112
Data Source
AI summary
An ionizer 1 including an ionization chamber 10, a sample gas introduction port 14 provided in the ionization chamber 10 for introducing sample gas, an electron beam emitting section 11 which emits an electron beam toward the ionization chamber 10, electron beam passage openings 10a and 10b which are formed on a path of the electron beam emitted from the electron beam emitting section 11 on a wall of the ionization chamber 10 and has a length in a direction of the path longer than a width of a cross section orthogonal to the direction, and an ion outlet 10c provided in the ionization chamber 10 for emitting an ion of the sample gas generated by irradiation with the electron beam, and a mass spectrometer 60 including the ionizer 1.