Quartz Electrode Aging for Discharge Ionization Current Detectors
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Solution Overview
Problem
Discharge ionization current detectors using dielectric-barrier discharge face challenges in reducing the background noise of detection signals, particularly due to adsorbed water on quartz electrodes, which affects sensitivity and dynamic range, especially when high sensitivity is required.
Innovation Solution
An aging treatment method involving the use of mixed inert gases with greater atomic weight than plasma gases to suppress initial gas discharge and promote desorption of adsorbed molecules, reducing background noise by continuously generating dielectric-barrier discharge with a cleaning gas mixture during the treatment process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If quartz is used as the dielectric material for covering the discharge electrode, then the stability of plasma generation is improved and electrode deterioration is suppressed, but adsorbed water on the quartz surface increases the background of the detection signal
Solution Approach 1:
The patent applies a preliminary aging treatment to the quartz dielectric material before actual use. This treatment involves exposing the quartz to plasma or heating it to high temperatures to pre-remove adsorbed water and other contaminants. By performing this cleaning action in advance, the background signal is reduced before measurements begin, while maintaining the quartz's plasma generation stability during operation.
2Object-generated harmful factors
If baking treatment is applied to remove adsorbed water on quartz, then the background of the detection signal is reduced, but the treatment time increases to several hours to several days
Solution Approach 1:
The patent changes the parameter of the treatment method from thermal baking to plasma treatment. Plasma treatment achieves the same effect of removing adsorbed water but in a much shorter time period. The plasma provides highly reactive species that rapidly desorb and decompose adsorbed molecules on the quartz surface, reducing the treatment time from hours/days to minutes or short periods.
Solution Approach 2:
The patent replaces the thermal mechanism (baking) with a plasma chemical mechanism. Instead of using heat to desorb water molecules, the patent uses plasma-generated reactive species (ions, electrons, radicals) to chemically interact with and remove adsorbed contaminants more efficiently and rapidly.
3Ease of operation
If plasma gas is used for aging treatment, then the treatment is simple, but the background noise reduction is insufficient compared to using mixed inert gases with greater atomic weight
Solution Approach 1:
The patent changes the parameter of the aging treatment gas from pure plasma gas to a mixture containing inert gases with greater atomic weight (such as argon or xenon). These heavier inert gases have different plasma characteristics that enhance the removal of adsorbed water and contaminants from the quartz surface, achieving superior background noise reduction compared to using plasma gas alone.
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 method significantly reduces background noise to levels unattainable with conventional treatments, enhancing detection sensitivity and achieving higher signal-to-noise ratios with the same processing time, thereby improving the overall performance of the detector.
Implementation Method 1
there is a discharge ionization current detector which adopts a method for generating plasma by dielectric-barrier discharge
Implementation Method 2
generating plasma by dielectric-barrier discharge (Patent Document 1)
Implementation Method 3
since the surface of a discharge electrode is covered with a dielectric material, there is not much emission of thermal electrons, secondary electrons and the like that occur in the case of generating discharge between metal electrodes
Implementation Method 4
Quartz has adsorption with respect to water, and adsorbed water will be present on the surface of quartz exposed to air
Implementation Method 5
the adsorbed water on the surface of quartz covering the discharge electrode is ionized and detected
Implementation Method 6
the adsorbed water on the quartz is removed by applying, after installation of the detector, a baking treatment of heating the detector at a temperature higher than the temperature to be used for several hours to several days
Implementation Method 7
heating the detector at a temperature higher than the temperature to be used for several hours to several days
Implementation Method 8
an aging treatment of performing plasma generation same as at the time of normal measurement at a plasma generation section
Implementation Method 9
continuously generating dielectric-barrier discharge with a cleaning gas mixture during the treatment process
Data Source
AI summary
An aging treatment is performed by using cleaning gas obtained by mixing inert gas, as an impurity, to plasma gas. Plasma generation by dielectric-barrier discharge is performed until a predetermined period of time has elapsed by applying high AC voltage to an electrode while supplying the cleaning gas to a dielectric tube from a gas inlet.