INP

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

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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.

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Framework of unified nonequilibrium plasma model and collisional-radiative model for characterisation of microdischarges in metal vapours of Cd and Zn - dataset

Thermal Plasma Technology

The dataset provides the data related to the modelling of microdischarges in metal vapour of cadmium and zinc. The characterisation of the microdischarges was done in a framework that combined a unified nonequilibrium plasma model and a collisional-radiative model. The plasma model provided the basic plasma parameters (number densities of ground state neutral and singly charged species and their energies, electric field, discharge voltage). Number densities of excited atomic states were obtained on a second stage employing a collisional-radiative model and the already known plasma parameters. This modelling framework allowed one to obtain spatially and temporally resolved plasma parameters and the population of the excited atomic states in the entire discharge gap during the separation of the electric contacts. The modelling work was supported by electrical measurements, high-speed imaging and optical emission spectroscopy. The experimental findings enabled the calibration of the plasma model with respect to the discharge voltage and a qualitative and to some extent quantitative comparison of computed and measured spectral intensities.

microdischarge
metal vapour
cadmium
zinc
nonequilibrium
collisional-radiative model
FieldValue
Group
INP
PTB Braunschweig
Authors
Baeva, Margarita
Jovanović, Aleksandar
Methling, Ralf
Bratek, Dominik
Hilbert, Michael
Uber, Carsten
Uhrlandt, Dirk
Release Date
2026-05-27
Identifier
d8420686-6b4f-40b9-b02d-2e13b4e3c08a
Permanent Identifier (DOI)
10.34711/inptdat.1030
Permanent Identifier (URI)
https://www.inptdat.de/node/1030
Plasma Source Name
microdischarge
Plasma Source Application
explosion protection
Plasma Source Specification
DC
thermal
Plasma Source Properties

The electrode configuration includes a cathode made of cadmium (Cd) and zinc (Zn) and an anode made of tungsten (W) with lengths of 10mm and a diameter of 100 μm each. The length of the plasma region varies from 20 μm up to 160 μm during the contact separation.
Plasma Source Procedure

An electric contact of a wire (anode) is established on the rough surface of a metal block (cathode). The wire is pulled away from the surface which initiates an electric discharge. The main discharge develops in metal vapour at distances between 20 μm and ∼ 200 μm (the so-called microdischarges). The wire moves further away from the surface, the released heat causes a thermochemical reaction, which can lead to the formation and the development of a flame front.
Plasma Medium Name
Cd
Zn
Plasma Medium Properties

The plasma is assumed to contain electrons and heavy particles of Cd or Zn atoms and singly charged Cd+ or Zn+ ions in their ground states. Admixture of air/H2 appears after the main microdischarge.
Plasma Medium Procedure

Spark ignition occurs during the contact separation at a constant current of 60 mA. Initially, the spark is ignited in the metal vapour of Cd or Zn. Later on the gas characterising the explosive atmopshere (a mixture air/H2) is supposed to mix with the metal vapour.
Plasma Target Name
Cd cathode
Zn cathode
W anode
Plasma Target Properties
Melting and evaporation of the cathode made of Cd or Zn. Thermo-field emission from the Cd/Zn cathode with precomputed values of the electric current density as a function of the electric field and the temperature on the cathode
Plasma Diagnostics Name
fluid model
voltage measurement
OES
electrical measurements
collisional-radiative model
Plasma Diagnostics Properties

A framework that combines a unified nonequilibrium plasma model and a collisional-radiative model is employed. The plasma model provides the basic plasma parameters (number densities of ground state neutral and singly charged species and their energies, electric field, discharge voltage). Number densities of excited atomic states were obtained on a second stage employing a collisional-radiative model and the already known plasma parameters. This modelling framework allowed one to obtain spatially and temporally resolved plasma parameters and the population of the excited atomic states in the entire discharge gap during the separation of the electric contacts.
The electrical characteristics of the discharge have been studied and quasi-stationary current-voltage characteristics have been obtained by using a setup that includes a DC control system, oscilloscope, providing the electrical parameters with a time step of 1.6 μs, long distance microscope, image intensifier, and a high-speed camera.
Plasma Diagnostics Procedure

The model equations are solved using a fully coupled approach. The electric current in the model has a constant value of 60mA. A steady-state solution is sought for a gap length of 20 μm to mimic the initial two phases of contact opening. Then, a deforming mesh approach is applied to simulate the moving electrode. The discharge gap was increased from 20 μm up to 160 μm with a speed of 0.14m/s.
A full discharge image was recorded for each wavelength with significant emission. 2D spectral images for Cd and Zn are provided.
Language
English
License
Creative Commons Attribution 4.0 International (CC BY 4.0)
Public Access Level
Public
Contact Name
Baeva, Margarita
Contact Email
baeva@inp-greifswald.de

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