Kinga Kutasi, Aranka Derzsi, Zoltán Donkó, Péter Hartmann, Ihor Korolov, Anikó Zsuzsa Kovács#, Péter Magyar#, Pál Mezei, Károly RózsaA
Our research activities are related to the different physical and chemical aspects of low temperature – non-equilibrium – plasmas at low (10-1000 Pa) and atmospheric pressures, and to their possible use for future emerging technologies. Furthermore, we also make use of the plasma environment of the low-pressure gas discharges to study atomic processes, as well as the collective phenomena occurring in many-particle systems using the dusty (strongly-coupled) plasma as model system. In the following, we briefly introduce some of our recent achievements grouped around our four main research directions.
Gas discharge physics. — Most of our research has concentrated on the behavior of charged particles in low-ionization-degree plasmas excited by radio-frequency waveforms. We have experimentally investigated the breakdown of hydrogen and deuterium gases and carried out numerical simulations to gain detailed insight into the build-up of electrical current conduction across the gas. Numerical, particle-based simulations have been developed to understand the plasma-chemical processes taking place in reactive oxygen plasmas. Studying the effects of "tailoring" the driving voltage waveform (by applying multiple consecutive harmonics of a base harmonic radio-frequency signal), we followed the changes in the dynamics of the electrons and ions in the plasmas and demonstrated the possibility of controlling the ion energy distribution functions, which are of great importance in surface processing plasma applications. The interaction between the plasma and the surrounding surfaces was also investigated via including surface processes (electron reflection and secondary electron emission from surfaces) in the discharge models. Simulations as well as experiments have been conducted with different gases to uncover the effects of negative ions, and more generally, effects of ion dynamics on the properties of capacitively coupled plasmas driven by customized voltage waveforms. Nonlinear and resonance effects occurring in these plasmas have also been addressed by computational simulations.
Strongly coupled plasmas. — Heat conduction in strongly magnetized, highly correlated plasmas has been investigated via molecular dynamics simulations. In a classical ideal plasma, a magnetic field is known to reduce the heat conductivity perpendicular to the field, whereas it does not alter the one along the field. We have shown that in strongly correlated plasmas, which occur at high pressure and/or low temperature, a magnetic field reduces the perpendicular heat transport much less and even enhances the parallel transport. These observations have been explained by the competition of kinetic, potential, and collisional contributions to the heat conductivity. Molecular-dynamics (MD) simulations of a strongly coupled binary ionic mixture have revealed the appearance of sharp minima in the species-resolved dynamical density fluctuation spectra. This phenomenon was found to be
# Ph.D student
A Associate fellow
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reminiscent of the well-known Fano anti-resonance, occurring in various physical processes.
We gave a theoretical analysis using the quasi-localized charge approximation, and demonstrated that the observed phenomenon in the equilibrium spectrum is a novel manifestation of the Fano mechanism.
Dusty plasmas. — Experiments and particle-based kinetic simulations were performed to obtain the equilibrium levitation height of dust particles in plane-parallel electrode discharges in low-pressure argon gas, established by combined RF and DC excitation. Non-equilibrium molecular dynamics simulation studies were performed on the dynamic (complex) shear viscosity of a 2D Yukawa system. Results include the identification of a non-monotonic frequency dependence of the viscosity at high frequencies and shear rates, of an energy absorption maximum (local resonance) at the Einstein frequency of the system at medium shear rates, of an enhanced collective wave activity, when the excitation is near the plateau frequency of the longitudinal wave dispersion, and the emergence of significant configurational anisotropy at small frequencies and high shear rates.
Discharge plasmas for surface treatment. — Oxygen content and UV radiating active plasmas, as well as afterglows have great potentials for modification of surfaces. For biomedical applications, the modification of polymer surfaces are required for further grafting. We have developed an afterglow system, based on a flowing surface-wave microwave discharge, which makes possible the treatment of the in- and outside walls of small-diameter heat-sensitive polymer tubes. We have determined the operating conditions and the afterglow characteristics in order to optimize the application (Figure 1).
Figure 1. Afterglow reactor set-up for treatment of heat sensitive tubes.
Grants
OTKA K-105476: High performance modelling and simulation of low-temperature and strongly coupled plasmas (Z. Donkó, 2013-2016)
OTKA NN 103150: Dusty plasma: a laboratory for classical many-particle physics (P. Hartmann, 2012-2015)
OTKA K 104531: High and low-frequency discharges for biomedical applications and nanostructuring (K. Kutasi, 2012-2016)
NKFIH K-115805: Complex plasmas in action (P. Hartmann, 2015-2019)
COST Action MP1101 Biomedical Applications of Atmospheric Pressure Plasma Technology (Management Committee Member K. Kutasi 2012-2015)
COST Action TD1208 Electrical discharges with liquids for future applications (Manager Committee Members K. Kutasi, I. Korolov 2013-2016)
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International cooperation
Boston College
Ruhr Universität Bochum Baylor University Texas
Institute of Physics Belgrade (Belgrade, Serbia), Interaction of discharge plasmas with living cells (Zoran Lj. Petrovic, Nevena Puac)
Josef Stefan Institute Ljubljana (Ljubljana, Slovenia), Surface treatments in afterglow plasmas (Miran Mozetic)
Institut Jean Lamour Ecole des Mines Nancy (Nancy, France), Gabriel Lippmann Centre Luxembourg (Luxembourg) Elementary processes in afterglow plasmas (Thierry Belmonte, David Duday)
West Virginia University (Julian Schulze)
Publications
Articles
1. Bastykova NK, Kovács AZ, Korolov I, Kodanova SK, Ramazanov TS, Hartmann P, Donkó Z:
Controlled Levitation of Dust Particles in RF+DC Discharges. CONTRIB PLASM PHYS 55:(9) pp. 671-676. (2015)
3. Derzsi A, Korolov I, Schungel E, Donko Z, Schulze J: Effects of fast atoms and energy-dependent secondary electron emission yields in PIC/MCC simulations of capacitively coupled plasmas. PLASMA SOURCES SCI T 24:(3) Paper 034002. 14 p. (2015)
4. Derzsi A, Schungel E, Donko Z, Schulze J: Electron heating modes and frequency coupling effects in dual-frequency capacitive CF4 plasmas. OPEN CHEM 13:(1) pp. 346-361. (2015) 5. Dyatko N, Donkó Z: Bistable solutions for the electron energy distribution function in
electron swarms in xenon: A comparison between the results of first-principles particle simulations and conventional Boltzmann equation analysis. PLASMA SOURCES SCI T 24:(4) Paper 045002. 9 p. (2015)
6. Korolov I, Donkó Z: Breakdown in hydrogen and deuterium gases in static and radio-frequency fields. PHYS PLASMAS 22:(9) Paper 093501. (2015)
7. Korolov I, Kalman GJ, Silvestri L, Donkó Z: The Dynamical Structure Function of the One-Component Plasma Revisited. CONTRIB PLASM PHYS 55:(5) pp. 421-427. (2015)
8. Kovács AZ, Hartmann P, Donkó Z: Periodically sheared 2D Yukawa systems. PHYS PLASMAS 22:(10) Paper 103705. (2015)
9. K Kutasi, Z Károly: Editors’ preface for the special issue “5th Central European Symposium of Plasma Chemistry” OPEN CHEM 13:(1) Paper 10.1515/chem-2015-0046.
(2015)
10. Mozetič M, Primc G, Vesel A, Zaplotnik R, Modic M, Junkar I, Recek N, Klanjšek-Gunde M, Guhy L, Sunkara MK, Assensio MC, Milošević S, Lehocky M, Sedlarik V, Gorjanc M,
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Kutasi K, Stana-Kleinschek K: Application of extremely non-equilibrium plasmas in the processing of nano and biomedical materials. PLASMA SOURCES SCI T 24:(1) Paper 015026. 13 p. (2015)
11. Ott T, Bonitz M, Donkó Z: Effect of correlations on heat transport in a magnetized strongly coupled plasma. PHYS REV E 92:(6) Paper 063105. 8 p. (2015)
12. Schulze J, Donkó Z, Derzsi A, Korolov I, Schuengel E: The effect of ambipolar electric fields on the electron heating in capacitive RF plasmas. PLASMA SOURCES SCI T 24:(1) Paper 015019. 13 p. (2015)
13. Schüngel E, Donkó Z, Hartmann P, Derzsi A, Korolov I, Schulze J: Customized ion flux-energy distribution functions in capacitively coupled plasmas by voltage waveform tailoring. PLASMA SOURCES SCI T 24:(4) Paper 045013. 6 p. (2015)
14. Schüngel E, Brandt S, Donkó Z, Korolov I, Derzsi A, Schulze J: Electron heating via self-excited plasma series resonance in geometrically symmetric multi-frequency capacitive plasmas. PLASMA SOURCES SCI T 24:(4) Paper 044009. 18 p. (2015)
15. Schüngel E, Brandt S, Korolov I, Derzsi A, Donkó Z, Schulze J: On the self-excitation mechanisms of plasma series resonance oscillations in single- and multi-frequency capacitive discharges. PHYS PLASMAS 22:(4) Paper 043512. 5 p. (2015)
16. Silvestri L, Kalman GJ, Donkó Z, Hartmann P, Kählert H: Fano-like anti-resonances in strongly coupled binary Coulomb systems. EUROPHYS LETT 109:(1) Paper 15003. 5 p.
(2015)
17. A Tóth, K Szentmihályi, Zs Keresztes, I Szigyártó, D Kovacik, M Cernak, K Kutasi: Layer-by-layer assembly of thin organic films on PTFE activated by cold atmospheric plasma.
OPEN CHEM 13: pp. 557-563. (2015)
18. Wilczek S, Trieschmann J, Schulze J, Schuengel E, Brinkmann RP, Derzsi A, Korolov I, Donkó Z, Mussenbrock T: The effect of the driving frequency on the confinement of beam electrons and plasma density in low-pressure capacitive discharges. PLASMA SOURCES SCI T 24:(2) Paper 024002. 13 p. (2015)
Conference proceedings
19. Kutasi K: Lézerspektroszkópiai módszerek a plazmafizikában (Laserspectroscopic methods in plasma physics, in Hungarian). In: Az ELI-ALPS az oktatásban Kecskemét Hungary 30.01.2015 Eds.: Borossáné Tóth S, Nagyné Szokol Á, Veres M, Kecskeméti Főiskola, 2015.p. 78 (ISBN:978-615-5192-27-2)
See also: S-Q.2
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