Mass Spectrometer Filament Isolation for Ion Extraction
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Solution Overview
Problem
Conventional mass spectrometers with electron ionization sources face reduced ion detection sensitivity due to prioritizing ion production efficiency over ion extraction efficiency, leading to disturbances in the electric fields within the ionization chamber.
Innovation Solution
The mass spectrometer design positions the filament farther from the ionization chamber to minimize the penetration of the thermion-accelerating electric field, optimizing the distance and opening area of the electron injection port to balance ion production and extraction efficiencies, with a preferred ratio of filament-to-ionization chamber distance and port opening area to enhance ion extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the filament is placed close to the electron injection port, then the ion production efficiency is improved, but the overall ion detection sensitivity is decreased due to reduced ion extraction efficiency
Solution Approach 1:
By segmenting the ion source into separate electron injection and ion extraction zones, the patent ensures that ion production and ion detection processes do not interfere with each other, thereby maintaining high ion detection sensitivity while preserving ion production efficiency.
Solution Approach 2:
The patent optimizes key parameters including the filament-to-ionization chamber distance, electron injection port dimensions, and potential difference values to achieve a balance between ion production and extraction efficiencies, ultimately improving overall ion detection sensitivity.
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 improves ion detection sensitivity by preventing electric field disturbances, allowing for more efficient ion extraction and transportation to the mass analyzer, resulting in higher signal strength and improved mass analysis sensitivity.
Implementation Method 1
a filament for generating thermions by heating
Implementation Method 2
an electric field with a potential gradient is created between the filament and the ionization chamber by providing a potential difference between them. Due to the action of this electric field, the thermions move toward the ionization chamber
Implementation Method 3
electron ionization (EI) is one of the most generally used methods. In electron ionization, sample molecules are introduced into an ionization chamber of a comparatively small capacity, which is placed under a vacuum atmosphere. These thermions come in contact with the sample molecules to ionize these molecules within the ionization chamber
Implementation Method 4
The ions thus produced within the ionization chamber are extracted to the outside by the action of an electric field created by a voltage applied to ion-extracting electrodes (e.g. a lens optical system) provided outside the ionization chamber
Data Source
AI summary
A filament 3 for generating thermions is remotely located from an ionization chamber 2 so that a thermion-accelerating electric field created by a potential difference between the filament 3 and the ionization chamber 2 is prevented from penetrating through an electron injection port 5 into the ionization chamber 2. This design eliminates the disturbance of an ion-extracting electric field created within the ionization chamber 2 by a voltage applied to lens electrodes 13, thus enabling ions produced within the ionization chamber 2 to be efficiently extracted and transported to a mass analyzer located at the subsequent stage. As a result, the level of detection signals of a detector is increased, so that the mass analysis can be performed with high sensitivity.