Dielectric Barrier Discharge Ionization Detector Light Path Design
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Solution Overview
Problem
Dielectric barrier discharge ionization detectors face challenges in reliably starting discharge when using argon gas, as conventional methods for emitting excitation light do not effectively initiate discharge, leading to unstable baseline detection signals.
Innovation Solution
The configuration includes a dielectric tube with a high-voltage electrode and ground electrodes arranged such that a cover is provided on the outer wall between the electrodes, and the light source emits excitation light in a controlled manner to prevent external discharge, ensuring the light axis is directed away from the cover, allowing reliable emission of excitation light to the discharge gas within the tube.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cover is provided on the outer wall of the dielectric tube to prevent external discharge, then discharge stability is improved, but excitation light cannot be effectively emitted to initiate discharge
Solution Approach 1:
A light-transmissive member is introduced as an intermediary component that allows excitation light to pass through while maintaining the cover's function of preventing external discharge. This mediator resolves the contradiction by selectively transmitting useful light while blocking harmful discharge paths.
Solution Approach 2:
The cover is designed with differentiated properties: a light-transmissive portion that allows excitation light passage and an opaque portion that prevents external discharge. This local quality differentiation enables the cover to simultaneously fulfill both conflicting requirements.
2Reliability
If the light source is positioned to emit excitation light through the cover, then discharge initiation is improved, but external discharge may occur causing detection signal instability
Solution Approach 1:
The light-transmissive member serves as a mediator that enables excitation light to reach the discharge gas while the cover structure prevents external discharge, thus maintaining detection signal stability without complicating the electrode arrangement.
Solution Approach 2:
The ground electrode unit is segmented into multiple ground electrodes arranged at different positions, allowing precise control of discharge regions and preventing external discharge while maintaining simple overall structure.
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 stabilizes the discharge and detection signal baseline by ensuring discharge occurs only within the dielectric tube, enhancing the reliability of the detection process and maintaining a stable output.
Implementation Method 1
The voltage applicator is connected to the high-voltage electrode and applies an alternating-current (AC) voltage across the high-voltage electrode and the ground electrode unit to cause discharge in the dielectric tube and to generate plasma from discharge gas
Implementation Method 2
The light source emits excitation light to discharge gas that flows through the dielectric tube... ions generated by light from the plasma, the ions being generated from a sample component in sample gas
Implementation Method 3
The electric charge collection portion includes a collection electrode that collects ions generated by light from the plasma, the ions being generated from a sample component in sample gas introduced in the gas flow channel
Data Source
AI summary
A light source emits excitation light to discharge gas that flows through a dielectric tube. A ground electrode unit includes a first ground electrode and a second ground electrode arranged at a distance from each other in an axial direction of the dielectric tube. A high-voltage electrode is provided between the first ground electrode and the second ground electrode. A first distance between the first ground electrode and the high-voltage electrode is shorter than a second distance between the second ground electrode and the high-voltage electrode. A cover is provided on an outer wall of the dielectric tube at a position between the first ground electrode and the high-voltage electrode. The light source is arranged to emit excitation light such that an optical axis thereof is directed toward a position where the cover is not provided on the outer wall of the dielectric tube.