Glow Plasma Signal Processing With Twice-Frequency Gas Detection
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Solution Overview
Problem
Conventional glow plasma discharge systems face challenges in maintaining stable plasma conditions and accurately processing signals at atmospheric pressure, leading to suboptimal signal-to-noise ratios and limited applicability in gas analysis.
Innovation Solution
The method involves generating oscillating electromagnetic fields to excite particles in a plasma cell, monitoring optical emissions at twice the excitation frequency, and using dynamic resonant feedback control to stabilize the plasma and improve signal processing, employing techniques like Lock-in detection and Fast Fourier Transforms for enhanced signal recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional glow plasma discharge systems are used at atmospheric pressure, then gas analysis capability is maintained, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent applies periodic modulation of the plasma discharge at a fundamental frequency, enabling the plasma to be excited in a cyclic manner. This periodic action creates distinct temporal phases within each cycle: a first phase optimized for plasma generation and a second phase for signal detection. By synchronizing detection with the second phase of each modulation cycle, the system achieves enhanced signal-to-noise ratio while maintaining atmospheric pressure operation capability.
Solution Approach 2:
The patent implements feedback control by monitoring optical emissions from the plasma and using this information to adjust operating parameters in real-time. The system detects plasma characteristics during the second phase and uses this feedback to optimize discharge conditions, thereby maintaining stable plasma conditions and improved signal quality at atmospheric pressure without requiring vacuum environments.
2Productivity
If plasma excitation frequency is increased to improve signal detection speed, then real-time analysis capability is improved, but plasma stability deteriorates
Solution Approach 1:
The patent utilizes periodic modulation at optimized frequencies that balance detection speed with plasma stability. By establishing a regular modulation cycle with distinct phases for excitation and detection, the system achieves predictable plasma behavior that maintains stability even at higher frequencies. The periodic nature allows the plasma to reset and stabilize during each cycle, preventing cumulative instability that would occur with continuous high-frequency excitation.
Solution Approach 2:
The patent implements dynamic control of discharge parameters by adjusting voltage, current, and timing within each modulation cycle based on real-time plasma conditions. The system can adapt the duration and intensity of the excitation phase versus the detection phase, allowing optimization of both detection speed and plasma stability. This dynamic adjustment enables the plasma to respond appropriately to changing conditions while maintaining overall stability.
3Stability of the object's composition
If continuous plasma discharge is used to maintain stable plasma conditions, then plasma stability is improved, but energy consumption increases
Solution Approach 1:
The patent employs periodic modulation of the plasma discharge rather than continuous operation. Within each modulation cycle, there is a first phase for plasma generation and a second phase for signal detection. By confining active plasma generation to specific phases rather than maintaining continuous discharge, the system reduces overall energy consumption while still achieving stable plasma conditions during the detection phases. The periodic on-off cycling allows energy-saving intervals while maintaining plasma stability when needed.
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 approach enables real-time, stable glow discharge optical emission spectroscopy with improved signal-to-noise ratios, allowing for more accurate gas analysis and broader applicability, including at atmospheric pressures.
Implementation Method 1
generating one or more oscillating electromagnetic fields to excite particles (atoms, molecules or charged species) within the cell, to produce a glow discharge from a plasma
Implementation Method 2
The subsequent radiative decay to lower energy levels results in the emission of characteristic photons of radiation that gives the name of 'glow' discharge
Implementation Method 3
monitoring one or more glow discharge optical emissions or one or more signals that correlate with the optical emissions, at twice the frequency of the one or more oscillating electromagnetic fields
Implementation Method 4
monitoring one or more glow discharge optical emissions or one or more signals that correlate with the optical emissions, at twice the frequency of the one or more oscillating electromagnetic fields
Implementation Method 5
employing techniques like Lock-in detection and Fast Fourier Transforms for enhanced signal recovery
Implementation Method 6
employing techniques like Lock-in detection and Fast Fourier Transforms for enhanced signal recovery
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
Provided are methods, apparatuses and systems for enhanced determination of the gas composition of a sample gas using glow discharge optical emission spectroscopy (GD-OES) for gas analysis. A first method comprises: generating one or more oscillating electromagnetic fields within a plasma cell to excite particles within the cell, to produce a glow discharge plasma in the plasma cell, and controlling the operating conditions for the plasma cell while flowing a gas mixture through the plasma cell to maintain glow discharge optical emissions from the plasma within a desired operating range; and monitoring one or more glow discharge optical emissions from the plasma in the plasma cell; wherein said monitoring of the optical emissions comprises measuring the optical emissions, or measuring a signal that correlates with the optical emissions, at twice the plasma excitation frequency; and processing the signal during each excitation cycle of the electromagnetic excitation, to determine the concentration of a gas within a gas mixture flowing through the plasma cell.