Dielectric Barrier Discharge Ionization Detector Creeping Discharge
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Solution Overview
Problem
Conventional Ar-BIDs have a lower signal-to-noise (SN) ratio due to the expansion of the plasma generation area caused by creeping discharge, which results in a single-side barrier discharge and increased noise levels.
Innovation Solution
The design includes a dielectric barrier discharge ionization detector with a ground electrode longer than the initiation distance for creeping discharge, preventing the expansion of the plasma generation area and maintaining a double-side barrier discharge, thereby improving the SN ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ground electrode is made longer than the initiation distance for creeping discharge, then the plasma generation area is confined and SN ratio is improved, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by adjusting the length of the ground electrode to exceed the initiation distance for creeping discharge. This parameter modification transforms the discharge mode from single-side barrier discharge to double-side barrier discharge, thereby confining the plasma generation area and improving the SN ratio without requiring complex additional components
Solution Approach 2:
The dielectric tube serves as an intermediary element that enables the dielectric barrier discharge. By positioning the ground electrode beyond the initiation distance, the dielectric tube mediates the discharge process, preventing creeping discharge while maintaining stable plasma generation in the confined area between the high-voltage electrode and the extended ground electrode
2Measurement precision
If the plasma generation area is confined to maintain double-side barrier discharge, then SN ratio is improved, but the discharge voltage requirement increases
Solution Approach 1:
The patent modifies the electrode geometry parameter by extending the ground electrode length, which changes the electric field distribution and discharge characteristics. This parameter change enables double-side barrier discharge mode that confines plasma to the desired area while managing voltage requirements through the dielectric barrier mechanism
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 suppresses creeping discharge and maintains a stable plasma generation area, enhancing the SN ratio and detection accuracy in Ar-BIDs.
Implementation Method 1
a low-frequency AC high voltage is applied to plasma-generating electrodes circumferentially formed around a tube made of a dielectric material, such as quartz glass ('dielectric tube'), to ionize an inert gas supplied into the tube line of the dielectric tube and thereby form atmospheric-pressure non-equilibrium plasma
Implementation Method 2
Due to the effects of the light emitted from this plasma (vacuum ultraviolet light), excited species and other elements, the sample components in a sample gas introduced into the charge-collecting section are ionized
Implementation Method 3
The resulting ions are collected through a collecting electrode to generate detection signals corresponding to the amount of ions
Data Source
AI summary
A dielectric barrier discharge ionization detector Includes: a dielectric tube; a high-voltage electrode connected to an AC power source and circumferentially formed on the outer wall of the dielectric tube; upstream-side and downstream-side ground electrodes and circumferentially formed above and below the high-voltage electrode; a discharging section for generating electric discharge to create plasma, from a gas containing argon; and a charge-collecting section for ionizing sample-gas components by the plasma and detecting an ion current formed by the ionized components. The detector also satisfies one or both of the following conditions: the upstream-side ground electrode is longer than a creeping discharge initiation distance between a tube-line tip member at the upper end of the dielectric tube and the high-voltage electrode; or the downstream-side ground electrode is longer than a creeping discharge initiation distance between the high-voltage electrode and the charge-collecting section.