Laboratory of Electrophysics

Department:   Department D 6 - Electrical Engineering and Electrophysics
Head:   Ing. Jiří Šonský, Ph.D.

Laboratory of electrophysics deals with experimental research of dynamic phenomena in electric arcs and thermal plasma jets including influence of these phenomena on interactions with injected solid particles. In most of experiments the thermal plasma is generated by an electric arc in a plasma torch. The arc and plasma jet at the output of the plasma torch is observed using optical methods comprising the application of high-speed CCD cameras and multi-channel systems working with optical fibers and photodiodes. Multi-directional recording is used for spatial reconstruction of dynamic processes in the plasma jet with a high temporal resolution. The acquired experimental data are processed by methods of correlation analysis, fast Fourier transform, wavelet analysis and computations of correlation dimensions.

Research of dynamic phenomena in thermal plasma by high-speed CCD camera


Example of record by high-speed CCD camera (decelerated 500×)

3D reconstruction of plasma jet 3D reconstruction of plasma jet
3D reconstruction of plasma jet and difference of pictures (ti – ti+1) created by inverse Radon transformation showing coherent structures

Experiments and analyses

Laboratory of electrophysics deals with experimental research of dynamic phenomena in electric arcs and thermal plasma jets including influence of these phenomena on interactions with injected solid particles. In most of experiments the thermal plasma is generated by an electric arc in a plasma torch.

high-speed CCD cameras and multi-channel systems high-speed CCD cameras and multi-channel systems

The arc and plasma jet at the output of the plasma torch is observed using optical methods comprising the application of high-speed CCD cameras and multi-channel systems working with optical fibers and photodiodes.

optical methods optical methods optical methods

Multi-directional recording is used for spatial reconstruction of dynamic processes in the plasma jet with a high temporal resolution.

analysis analysis analysis

The acquired experimental data are processed by image processing, by methods of correlation analysis, fast Fourier transform, wavelet analysis and computations of correlation dimensions.

Analysis of the complex dynamic phenomena in plasma flow, its stability, interactions with particles and surfaces and reproducibility of such processes parameters is crucial to various industrial applications. Among them we can name plasma spraying, plasma etching, dangerous agents decomposition or plasma chemistry in general. Experimental research conducted in our laboratory of electrophysics contributes to better understanding of processes in plasma with possible various industrial applications.

Spectral analysis of plasma dynamics

Reconstruction of the jet radiation intensity
Reconstruction of the jet radiation intensity temporal evolution in plasma cross-section.

Distribution of the significant oscillations in plasma
Distribution of the significant oscillations in plasma Distribution of the significant oscillations in plasma
Distribution of the significant oscillations in plasma
Distribution of the significant oscillations in plasma Distribution of the significant oscillations in plasma
Distribution of the significant oscillations in plasma. Spectral analysis by Fourier transform. Difference between higher and lower frequencies distribution.

Distribution of 300Hz oscillation for various gas flow rates Distribution of 300Hz oscillation for various gas flow rates Distribution of 300Hz oscillation for various gas flow rates Distribution of 300Hz oscillation for various gas flow rates
Distribution of 300Hz oscillation for various gas flow rates.

Temporal evolution of oscillations
Temporal evolution of oscillations of various frequencies acquiered by wavelet analysis (3300× decelerated).

Reconstruction of temporal evolution
Reconstruction of temporal evolution of 580Hz oscillations in the plasma flow cross-section (9400× decelerated).

3D reconstruction of dynamic process in plasma flow

Three-dimensional reconstruction of plasma flow and difference between two consequent reconstructions.

  • Decelerated approximately 500 times, period between the frames being 48 microseconds, reconstruction is calculated from three directions separated by 120°.

rekonstrukce proudu plazmatu rekonstrukce proudu plazmatu
gas flow rate ... 0[g/s] axial + 0.5[g/s] tangential

rekonstrukce proudu plazmatu rekonstrukce proudu plazmatu
gas flow rate ... 0.5[g/s] axial + 0[g/s] tangential

rekonstrukce proudu plazmatu rekonstrukce proudu plazmatu
gas flow rate ... 0.5[g/s] axial + 0.5[g/s] tangential

  • Decelerated approximately 1000 times, period between the frames being 8 microseconds, reconstruction is calculated from two directions separated by 90°. Gas flow rate 60 l/min.

rekonstrukce proudu plazmaturekonstrukce proudu plazmatu

Analysis of complexity of plasma dynamics

Analysis of dynamic complexity by estimation of correlation dimension.


Evolution of the arc current dynamics visualized in the reconstructed phase space.


Points density of phase space trajectory representing plasma radiation dynamics visualized in the reconstructed phase space.


Distribution of the estimated complexity in the plasma flow.


Distribution of the estimated complexity in the plasma flow and spatial gradient of this distribution.

Possible application

Example of Cu droplet tracking. Cu droplet (diameter is approximately 1.5 mm) is drifted by the plasma flow (velocity ofthe droplet is 2.17 m/s). Animation is decelerated 10 000 times.


Cu droplet after splashing on solid surface and cooling out.


Trajectories of different-sized Cu droplets.

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