INP

Leibniz Institute for Plasma Science and Technology
Felix-Hausdorff-Str. 2
17489 Greifswald
GERMANY

https://www.inp-greifswald.de/en/
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The Leibniz Institute for Plasma Science and Technology (INP) is the largest non-university institute in the field of low temperature plasmas, their basics and technical applications in Europe. The institute carries out research and development from idea to prototype. The topics focus on the needs of the market. At present, plasmas for materials and energy as well as for environment and health are the focus of interest.

Cite Dataset

Formation mechanisms of striations in a filamentary dielectric barrier discharge in atmospheric pressure argon - dataset

The results of the modelling of a filamentary dielectric barrier discharge (DBD) in argon at atmospheric pressure obtained using a time-dependent and spatially two-dimensional fluid-Poisson model in axisymmetric geometry are provided in this dataset. The model was employed to investigate the formation mechanisms of the striations along the discharge channel in a one-sided DBD arrangement with a 1.5 mm gap powered by a sinusoidal high voltage applied at the metal electrode. The discharge conditions were chosen to resemble the experimental conditions for which striations have been observed. It was found that the striations form in both half-periods during the transient glow phase, which follows the streamer breakdown phase. The modelling results showed that the distinct striated structures feature local spatial maxima and minima in charged and excited particle densities, which were more pronounced during the positive polarity. Their formation was explained by a repetitive stepwise ionisation of metastable argon atoms and ionisation of excimers, causing a disturbance of the spatial distribution of charge carriers along the discharge channel. The results emphasise the importance of excited states and stepwise ionisation processes on the formation of repetitive ionisation waves, eventually leading to striations along the discharge channel.

FieldValue
Group
Authors
Release Date
2023-04-25
Identifier
635c4fbc-f299-48c1-a843-c6dced54cf4c
Permanent Identifier (DOI)
Permanent Identifier (URI)
Is supplementing
Plasma Source Name
Plasma Source Application
Plasma Source Specification
Plasma Source Properties

The modelling was performed for the DBD in an asymmetric arrangement with a 1.5 mm gap, electrode radius of 2 mm and 0.5 mm thick dielectric (alumina, relative permittivity 9) covering grounded electrode, driven by sinusoidal voltage (voltage amplitude of 1.3 kV and frequency of 60 kHz, corresponding to a period of T = 16.67 microseconds).

Plasma Medium Name
Plasma Medium Properties

Pure argon, gas pressure is 760 Torr, constant gas temperature of 300 K

Plasma Diagnostics Name
Plasma Diagnostics Properties

Model: Fluid-Poisson model in cylindrical geometry;
Computational software: COMSOL Multiphysics® v. 5.6 (www.comsol.com, COMSOL AB, Stockholm, Sweden);
Numerical method: Finite element method;
Element type: Linear Lagrange elements for particle balance equations, quadratic Lagrange elements for Poisson equation, linear discontinuous Lagrange elements for the surface charge density balance equation;
Time-stepping: Backward differentiation formula (BDF), with automatically adapted time-step size and the BDF order (in the range from 1 to 2);
Solver: Fully coupled constant Newton solver, with the direct linear solver (PARDISO);
Tolerance: in range from 0.0001 to 0.001 (varied to prevent small time-stepping during the discharge in negative half-period);
Mesh: Manual remeshing was done to reduce calculation time, where the continuation of the calculations from the last calculated time step was performed after each remeshing. The mesh had in average 500 000 elements and about 3 million degrees of freedom (noting that coarser mesh was used during the off-phase).

Plasma Diagnostics Procedure

An atmospheric-pressure DBD in argon is investigated by means of time-dependent and spatially two-dimensional fluid-Poisson modelling in an axisymmetric geometry. The object of interest was formation of the striations along the discharge channel. The model comprises a set of balance equations for the particle number densities of electrons and the most important argon species (atomic Ar+ and molecular Ar2+ ions, as well as the lumped excited atomic Ar∗ and molecular Ar2∗ states of argon), Poisson’s equation for the electric potential and field, the electron energy balance equation and a balance equation for the surface charge density. The quasi-neutral initial conditions and physically-based boundary conditions, accounting for thermal flux and partial reflection of the particles, are used. The additional term describing the ion-induced emission of secondary electrons is included into the boundary conditions for the balance equations for the particle number density and energy density of electrons. The analysis of the spatiotemporal evolution of the particle species, electric field, mean electron energy and rates of electron production after reaching the quasi-periodic state was performed to determine the origin of the striations. The voltage and electric current, as well as the number densities, electric field and electron production rates were exported using LiveLink™ for MATLAB® (https://www.comsol.com/livelink-for-matlab) and post-processed using python3 (https://www.python.org) and Matplotlib (https://matplotlib.org).

Language
English
License
Public Access Level
Public
Contact Name
Jovanović, Aleksandar
Contact Email

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