Hollow Electrode Discharge Cell for Homogeneous Plasma
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Solution Overview
Problem
Existing discharge cell systems fail to produce a homogeneous, strongly excited, low-temperature, non-equilibrium plasma with controllable and repeatable parameters, limiting their effectiveness as diagnostic and calibration devices.
Innovation Solution
A discharge cell configuration featuring a first and second hollow electrode with a defined discharge gap, fluid pathway, and optic pathways, where the electrodes are positioned to satisfy specific criteria for high-voltage pulse constraints to ensure plasma homogeneity, including constraints on pulse amplitude, rise time, duration, and frequency, facilitating uniform plasma production and effective energy deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional discharge cell designs are used, then device simplicity is maintained, but plasma homogeneity and parameter controllability deteriorate
Solution Approach 1:
The discharge cell is divided into distinct functional zones: a discharge region where plasma is generated, a pre-ionization region with a corona discharge electrode, and a post-discharge region. This segmentation allows each zone to be optimized independently for its specific function, achieving homogeneous plasma through controlled spatial distribution of ionization processes
Solution Approach 2:
A corona discharge electrode is introduced as an intermediary element between the main discharge electrodes. This intermediate electrode creates a pre-ionization corona discharge that prepares the gas medium before the main discharge occurs, ensuring more uniform plasma formation and reducing discharge instability
2Power
If high-voltage pulses are applied to generate plasma, then plasma excitation strength is improved, but discharge instability increases
Solution Approach 1:
The discharge system operates with periodic high-voltage pulses at controlled frequencies (e.g., 1-100 kHz). This periodic action allows the plasma to be continuously regenerated and stabilized, with each pulse creating a controlled excitation event followed by a relaxation period, preventing cumulative instabilities while maintaining strong excitation
Solution Approach 2:
The discharge cell configuration incorporates parameters that provide natural feedback control: the corona discharge electrode responds to changes in gas ionization state, and the hollow electrode geometry provides distributed field distribution that self-regulates the discharge. This feedback mechanism stabilizes the discharge against high-voltage pulse variations
3Measurement precision
If plasma excitation is increased, then diagnostic reference quality is improved, but temperature control becomes difficult
Solution Approach 1:
The system utilizes controlled parameter changes in the high-voltage pulses (amplitude, duration, frequency) to independently adjust plasma excitation strength and temperature. By optimizing pulse width and frequency, the plasma achieves strong excitation for diagnostic references while maintaining low temperature through controlled energy deposition time, preventing excessive thermalization
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 solution enables the creation of a stable, strongly excited, low-temperature, non-equilibrium plasma with controllable parameters, enhancing the discharge cell's performance as a reference source for diagnostics and calibration, ensuring uniform gas excitation and minimizing discharge instability.
Implementation Method 1
Assuming the discharge has been generated by applying a high voltage electric pulse across a discharge gap
Implementation Method 2
setting the value of reduced electric field E/n in the discharge gap after it is overlapped by the ionization wave
Implementation Method 3
Short Pulsed Laser Techniques for Measurement of Multiple Properties in High Enthalpy Facilities
Data Source
AI summary
Described herein are systems and methods for ensuring plasma homogeneity in a discharge cell. The discharge cell may include a first hollow electrode and a second hollow electrode spaced away from the first electrode to define a discharge gap therebetween. A fluid inlet port may in fluid communication with an internal bore of the first electrode. A fluid outlet port may be in fluid communication with the discharge gap. A first pair of viewports may define a first optic pathway through the discharge gap. A second pair of viewports may define a second optic pathway through the discharge gap. A third pair of viewports may define a third optic pathway through the discharge gap, the third optic pathway defined through the hollow interior of the first and second electrodes.