Ionization Chamber Mid-Ring Electrode Potential Well Ion Compression
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Solution Overview
Problem
Ion mobility spectrometer (IMS) systems face challenges in maintaining precise control over ion disk width and resolution due to non-homogeneous electric fields in ionization chambers, leading to distorted ion peaks and poor analysis resolution.
Innovation Solution
An ionization chamber with a mid-ring electrode is used to generate a potential well, allowing ions to collect during compression and release as a high-density pulse into a drift region, improving ion signal and detection performance by controlling ion density and preventing ion leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a field-free ionization chamber is used to generate ions, then ion population increases, but ion leakage occurs and ion disk width control is poor
Solution Approach 1:
The ionization chamber is segmented into multiple regions by introducing ring electrodes at different axial positions. These electrodes create distinct electric field zones that allow independent control of ion generation, trapping, and release, thereby improving ion disk width control while maintaining ion population.
Solution Approach 2:
Different regions of the ionization chamber are assigned different electric field characteristics. The region near the ion source maintains field-free conditions for efficient ion generation, while regions near the ion gate have controlled electric fields to prevent leakage and shape the ion disk, achieving both high ion population and precise width control.
2Reliability
If retaining grid potential is increased to prevent ion leakage, then ion trapping improves, but ion signal intensity decreases
Solution Approach 1:
The retaining grid potential is made dynamic rather than static. The potential is adjusted in real-time based on ion population density and drift region conditions, allowing the system to maintain strong ion trapping when needed while preserving ion signal intensity when the grid potential is lowered for optimal ion transmission.
3Adaptability or versatility
If ion disk is allowed to expand during drift, then high-mobility analytes separate from low-mobility analytes, but peak resolution deteriorates
Solution Approach 1:
The ion disk is pre-compressed and pre-shaped in the ionization chamber before being injected into the drift region. This preliminary action creates a narrow, well-defined ion disk that maintains its integrity during drift, allowing analyte separation to occur without excessive disk expansion that would degrade peak resolution.
4Productivity
If ionization chamber electric field is made non-homogeneous to clear ions, then ion clearing improves, but ion disk width control is lost
Solution Approach 1:
The electric field clearing process is segmented into multiple stages using different ring electrodes. First, a strong non-homogeneous field clears ions efficiently from the ionization region. Then, a second stage with a different field configuration refines the ion disk width. This segmented approach maintains both clearing efficiency and width control precision.
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 potential well configuration enhances ion density and signal intensity, improving detection performance by maintaining ions near the ion gate until a high-density pulse is released into the drift region, thus enhancing spectral analysis resolution.
Implementation Method 1
the mid-ring electrode is charged to a first mid-ring potential that is less than the first ionization source potential and the first ion gate potential. The first mid-ring potential is configured to generate a potential well proximate the mid-ring electrode. The ions collect at the potential well.
Implementation Method 2
The samples are channeled to an ionization chamber that includes an ionizing source that ionizes the sample to form positive ions, negative ions, and free electrons.
Data Source
AI summary
An ionization chamber. The ionization chamber includes a vessel, an ionization source, an ion gate, and a mid-ring electrode. The vessel defines an ionization region. The vessel includes a first end axially disposed opposite a second end. The ionization source is located at the first end and generates ions. The ion gate is located at the second end of the vessel. The mid-ring electrode is located between the ionization source and the ion gate. During an ion compression stage, the ionization source is charged to a first ionization source potential, the ion gate is charged to a first ion gate potential, and the mid-ring electrode is charged to a first mid-ring potential that is less than the first ionization source potential and the first ion gate potential. The first mid-ring potential is configured to generate a potential well proximate the mid-ring electrode. The ions collect at the potential well.