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The theoretical and experimental results on plasma currents induced by acoustic-type solitons are generalized. Ion, electron, and dust-acoustic modes in plasma without magnetic field are considered in detail. It is shown that the generation of pulsed plasma currents with a significant direct component is an inherent property of solitons. The basic properties of soliton currents are established.

The action of the light pressure force on a bounded region of a 2D system of dust macroparticles is simulated using the molecular dynamics method. The dynamics of dust macroparticles in the quasi-2D structure (trajectories of particles, their mean square displacement, and kinetic energy) is analyzed for various values of the nonideality parameter and laser radiation power. It is shown that by varying the radiation power, it is possible to influence the self-diffusion processes and the value of chaotic velocity of particles. Analysis is performed for different initial values of the nonideality parameter of the unperturbed dust subsystem. It is found that the interparticle interaction results in an increase in the kinetic energy of particles in the region of action, as well as beyond it.

An experimental study of the cavitation flow around the National Advisory Committee for Aeronautics 0012 hydrofoil with different surface morphology was carried out in this work. The surface morphology was set by modern laser ablation technology. The average values and intensity of vapor–gas cavities were determined. It has been revealed that laser texturing delays the emerging cavitation and somewhat decreases its intensity at higher cavitation numbers. A decrease in the cavitation number leads to an increase in its intensity for a smooth hydrofoil in comparison with a rough one, which is also expressed in an increase in the frequency of cavities. The paper presents a comparison of the flow regime with equal cavitation numbers, which clearly describes the features of the development of a vapor–gas cavity on the suction side of the foil with different surface morphologies. The paper provides an explanation of the reasons for the influence of surface morphology on the development of cavities.

Complex structures, consisting of a large number of interacting subsystems, have the ability to self-organize and evolve, when the scattering of energy coming from the outside ensures the maintenance of stationary ordered structures with an entropy less than the equilibrium entropy. One of the fundamental problems here is the role of quantum phenomena in the evolution of macroscopic objects. We provide experimental evidence for the active Brownian motion and evolution of structures driven by quantum effects for micron-sized grains levitating in superfluid helium. The active Brownian motion of grains was induced by quantum turbulence during the absorption of laser irradiation by grains. The intensity of Brownian motion associated with quantum vortices increased by 6–7 orders of magnitude compared to the values from the Einstein formula. We observed the grain structures in a state far from thermodynamic equilibrium and their evolution to more complex organized structures with lower entropy due to the quantum mechanism of exceedingly high entropy loss in superfluid helium.

Using the modified method of Brownian dynamics, the dynamics of macroparticles with a uniform metal coating in a plasma-dust monolayer under the action of laser radiation was simulated. The time dependences of the root-mean-square and average linear displacements of particles were calculated for different initial effective parameters of nonideality and different intensities of laser radiation. A relationship was established that connects the effective parameter of nonideality of the dusty plasma system of active particles with the maximum value of the mean linear displacement of particles.

The results of a study on particles’ surfaces after being exposed to the near-electrode region of a radio frequency (RF) discharge are presented. It was experimentally displayed that metal starts being deposited on the surface of particles levitating above the lower electrode of the discharge chamber after switching the RF discharge on. For melamine-formaldehyde (MF) particles, the appearance of an island metal coating is observed after 30 min of plasma exposure. Eroded electrodes and elements of the gas discharge chamber may serve as a source of deposited material. In addition, an analysis of the surface and composition of particles placed on the upper electrode after 6 h of plasma exposure is presented. We reveal that the composition and structure of the particle coating changes during the experiment. The MF particles under exposure become eroded, and needle-like structures containing metals are formed on their surface. We also observe the formation of columnar structures from the products of erosion of electrodes on particles with a metal coating.

Studies of dusty plasma have been actively carried out for about a quarter of a century in many laboratories on Earth, and on board the International Space Station under microgravity conditions. At present, a new experiment is being prepared. We describe the goals and objectives of the experiment, its features and differences from previous experiments, explain the need for it in microgravity. The objective of the experiment is to study the evolution of the open dissipative systems of strongly interacting macroparticles in a gas-discharge plasma, to obtain data on phase transitions and dynamics of active Brownian particles and dynamics of defects and dislocations in plasma-dust structures. Key words: dusty plasma, microgravity, cosmic experiment, open thermodynamic systems, active Brownian particles

We present a detailed analysis of experimental study, which shows clear evidence of a two-stage melting process of a quasi-two-dimensional dusty plasma system in a high-frequency gas discharge. We accurately calculated global parameters of the orientational and translational order, as well as their susceptibilities to determine two critical points, related to “solid-to-hexatic” and “hexatic-to-liquid” phase transitions. The nature of the emerging defects and changes in their mutual concentration, in addition to the estimate of core energy of free dislocations also counts in favor of the formation of an intermediate hexatic phase. These results are fully consistent with the Berezinsky–Kosterlitz–Thouless theory.

Experimental data on the active Brownian motion of single particles in the RF (radio-frequency) discharge plasma under the influence of thermophoretic force, induced by laser radiation, depending on the material and type of surface of the particle, are presented. Unlike passive Brownian particles, active Brownian particles, also known as micro-swimmers, move directionally. It was shown that different dust particles in gas discharge plasma can convert the energy of a surrounding medium (laser radiation) into the kinetic energy of motion. The movement of the active particle is a superposition of chaotic motion and self-propulsion.

We present the results of an experimental study of the behavior of a colloidal plasma system formed by copper-coated and uncoated polymer particles under the action of laser irradiation. A comparative study of particle velocity distribution profiles depending on the power of the pushing laser was conducted. In the case of uncoated melamine-formaldehyde (MF) particles, we observed the well-known action of light pressure, causing shear stress in the colloidal plasma structure and leading to the occurrence of a laminar flow within the affected area. For the copper-coated MF particles, we revealed some additional patterns of behavior for the dust particles, i.e., kinetic temperature growth due to laser radiation absorption by the copper coating, as well as the appearance of chaotic particle motion. We believe that this happens due to the existence of defects in the coating, causing asymmetric heating of the particles, which in turn leads to chaotic deviations of the photophoretic force pushing the particles in different directions.

A new experimental setup for studying various phenomena in both cryogenic helium plasma and dusty plasma structures in a low-pressure gas discharge within the temperature range of 1.6–300 K is described. The setup is equipped with a modern data-acquisition system and high-speed video cameras to observe processes in dusty plasma structures. For the first time, dusty plasma structures were observed and studied at temperatures below 4 К.

We have studied experimentally the oscillatory process in the dusty plasma in the glow discharge stratum. It is shown that the oscillations are induced by the dust–acoustic instability, as a result of which dust–acoustic solitons are excited. The motion of dust particles in the electric field of solitons has been analyzed. It has been established that a soliton leads to a large-scale unidirectional transport of charged particles in the direction of its motion. The experimental results have been interpreted theoretically using the MHD model of the plasma.

We report on the results of analysis of the mean kinetic energy and the pair correlation function of polymer particles in a plasma–dust structure under the action of laser radiation. We have observed experimentally the crystal–liquid phase transition in the monolayer of particles levitating in the near-electrode layer of a capacitive high-frequency discharge. The coupling parameter of the dust system has been estimated. The results of analysis of the modification of the polymer dust particle surface after holding in the plasma are considered. We propose an explanation of the phase transition taking into account the role of the photophoretic force in the motion of macroparticles. The effect of the photophoretic force is associated with the modification of the dust particle surface in the plasma, as a result of which the particles can effectively absorb laser radiation.

The dusty plasma structures in a glow discharge of helium in a tube cooled by superfluid helium at a temperature of 1.6 K and higher have been studied experimentally. The bimodal dust plasma formed by clouds of polydisperse cerium dioxide particles and polymer nanoparticles has been analyzed. We have observed wave oscillations in the cloud of polymer nanoparticles (with a size up to 100 nm), which existed in a narrow temperature range from 1.6 to 2.17 K. Vortices have been observed in the dusty plasma structures at helium temperatures.

Experimental results on dust-acoustic wave study in a weakly coupled cryogenic dusty plasma within the DC glow discharge are discussed. Analysis of dust particle trajectories, their velocity distributions, and the pair correlation function allows us to conclude that the 3D dusty plasma structure studied at T = 83 K was most likely a gaseous structure.

The effect of a dc electric field on strongly nonideal Coulomb systems consisting of a large number (~104) of charged diamagnetic dust particles in a cusp magnetic trap are carried out aboard the Russian segment of the International Space Station (ISS) within the Coulomb Crystal experiment. Graphite particles of 100–400 μm in size are used in the experiments. Coulomb scatter of a dust cluster and the formation of threadlike chains of dust particles are observed experimentally. The processes observed are simulated by the molecular dynamics (MD) method.

There is a variety of cases in nature when the action–reaction symmetry is broken. In particular, suitable conditions for this are realized in colloidal suspensions and complex plasmas. Since the first theories and simulations of the nonreciprocal effective interactions between microparticles in complex plasmas were published in 1995–1996, there have been hundreds of studies in the theoretical development of this theme. However, despite such a rich theoretical background, one of the important unsolved problems is a direct experimental determination of the nonreciprocal interparticle interaction forces. Here, we studied experimentally in detail the forces of the nonreciprocal effective interaction between microparticles suspended a radio-frequency produced plasma sheath. For this purpose, an experimental method based on an analysis of the spectral density of random processes in an open dissipative two-particle system was developed. In contrast to previous investigations, the proposed method takes into account random and dissipative processes in the system, does not require a special design of the experimental setup and any external perturbations, pre-measurements of external fields and any assumptions about the type of interaction. We found that even small charge changes of one particle, caused by its thermal motion in a wake field of another particle, can lead to a significant change in the effective (measurable) interaction between the particles.

A multimodal dusty plasma formed in a positive column of the direct current glow discharge at superfluid helium temperatures has been studied for the first time. Formation of a liquid-like dusty plasma structure occurred after injection of polydisperse cerium oxide particles in the glow discharge. The coupling parameter ~10 determined for the dusty plasma structure corresponds very well to its liquid-like type. The cloud of nanoparticles and non-linear waves within the cloud were observed at T 6е, levitating in the gas discharge at the temperature ~2 K and pressure 4 Pa have been observed for the first time. Analysis of the experimental conditions and the filament composition allows us to conclude that the filaments and nanoclusters were formed due to ion sputtering of dielectric material during the experiments.

Properties of weakly dissipative dust-acoustic solitons are analyzed on the basis of the hydrodynamic and single-particle approximation (Lagrangian–Euler approach). Significant differences between dissipative and conservative solitons are found. Particle-wave microdynamic parameters such as trajectories, phase trajectories, and drift velocity of dust particles under the action of a cascade of solitons are calculated. It is shown that dissipation is responsible for the interconnection of solitons in the ensemble. In addition, dissipative solitons significantly affect the environment comparing with conservative ones. The heat release processes that determine the production of entropy are analyzed. The role of dissipation in the ordering of charged particles trajectories is revealed. The theoretical results are in a reasonable agreement with known experimental data.

The results of experimental and numerical analysis are presented for phase transitions in strongly nonequilibrium small systems of strongly interacting Brownian particles. The dynamic entropy method is applied to analysis of the state of these systems. Experiments are carried out with kinetic heating of the structures of micron-size particles in a laboratory rf discharge plasma. Three phase states of these small systems are observed: crystalline, liquid, and transient. The mechanism of phase transitions in cluster structures of strongly interacting particles is described.

Complex (dusty) plasmas of micron-sized CeO2 polydisperse particles in dc glow discharges at 77 and ∼ 10 K were experimentally investigated. It was obtained that dust structure in cryogenic gas discharge plasma can be a mixture of two fractions (components) with completely different dust ordering and dynamics. We observed under some specific conditions that fast-moving particles of one component diffuse through another component consisted of dust particles arranged in linear chains (strings). From experimental data analysis particle velocity distribution functions for each dust component were obtained. The possible nature of two-component dust structure formation was discussed. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Electrically charged (up to 107e) macroscopic superconducting particles with sizes in the micrometer range confined in a static magnetic trap in liquid nitrogen and in nitrogen vapor at temperatures of 77–91 K are observed experimentally. The macroparticles with sizes up to 60 μm levitate in a nonuniform static magnetic field B ~ 2500 G. The formation of strongly correlated structures comprising as many as ~103 particles is reported. The average particle distance in these structures amounts to 475 μm. The coupling parameter and the Lindemann parameter of these structures are estimated to be ~107 and ~0.03, respectively, which is characteristic of strongly correlated crystalline or glasslike structures.

Effects of microwave argon non-thermal plasma (NTP) on the facultative intracellular pathogen Listeria monocytogenes were studied. NTP treatment for 2 min caused a 3 log 10 decrease of wild type strain EGDe extracellular bacteria. Similar treatment of infected HEK293 cells caused a 1.5-fold decrease of intracellular EGDe bacteria. The intraphagosomal EGDeΔhly lacked the pore-forming toxin LLO was resistant to NTP. Cell pretreatment with NTP before infection increased EGDe invasion of human HEK293 and murine C26 cells 2.5 and 1.7-fold, respectively. HEK293 cell pretreatment did not affect invasion by EGDe ΔinlA that lacked the invasion factor InlA. Taken together, obtained results demonstrated that a direct NTP effect on intracellular L. monocytogenes was low, still NTP affected interactions between L. monocytogenes and the host cell.

We consider the results of experimental observation of melting of a plasma-dust monolayer (2D phase transition) in a low-pressure gas discharge. Pair and bond-angular correlation functions as well as the number of topological defects in the monolayer are measured and analyzed. The change of profile of the bond-angular correlation functions confirms the existence of the solid-hexatic phase-liquid phase transition, which completely correlates with the Berezinskii-Kosterlitz-Thouless theory.

A self-consistent model of plasma polarization around an isolated micron-sized dust particle under the action of an external electric field is presented. It is shown that the quasineutral condition is fulfilled and the formed volume charge totally screens the dust particle. The ion focusing and wake formation behind the dust particle are demonstrated for different ion mean free paths and the external electric fields. It is obtained that at low values of the external electric field the trapped ions play the main role in the screening of the dust particle charge. For high external electric fields, the density of trapped ions decreases and the dust particle is screened mainly by the free ions.

The experimental and theoretical investigations of the formation of dust particle clouds in the stratified positive column of a dc glow discharge in helium were performed. The size and shape of a dust cloud that levitated in the strong electric field of the striations in a vertically oriented discharge tube were measured under different helium pressures. Axial electric field strength was also experimentally estimated. A model for radial distributions of all dusty plasma parameters of the positive column of the dc glow discharge was developed to describe the obtained experimental results. The model is based on the solution of a non-local Boltzmann equation for an electron energy distribution function, drift-diffusion equations for ions and dust particles, and a Poisson equation for a self-consistent radial electric field. The experimental and calculated results show that the size of the dust cloud decreases with the increase in the gas pressure, and the axial electric field strength pressure dependencies have minima. At low gas pressures, the dust particle charge number density increases and exceeds the electron density that strongly influences the plasma parameters.The experimental and theoretical investigations of the formation of dust particle clouds in the stratified positive column of a dc glow discharge in helium were performed. The size and shape of a dust cloud that levitated in the strong electric field of the striations in a vertically oriented discharge tube were measured under different helium pressures. Axial electric field strength was also experimentally estimated. A model for radial distributions of all dusty plasma parameters of the positive column of the dc glow discharge was developed to describe the obtained experimental results. The model is based on the solution of a non-local Boltzmann equation for an electron energy distribution function, drift-diffusion equations for ions and dust particles, and a Poisson equation for a self-consistent radial electric field. The experimental and calculated results show that the size of the dust cloud decreases with the increase in the gas pressure, and the axial electric field strength pressure dependencies h...

A series of experiments on the modernized "Coulomb crystals" setup on board of the International Space Station (ISS) was performed. Formation of a cluster of charged and uncharged particles was observed. Excitation and damping of cluster oscillations, as well as its destruction in the high electric field were investigated. Charges of the particles were evaluated on the basis of their rate of expansion from the cluster. Some conclusions about the cluster structure have been presented.

The purpose of this work was to establish the influence of a regime of cold microwave argon plasma treatments on the physiological characteristics of human fibroblasts and keratinocytes. We used three regimes of plasma application: a single treatment, double treatment with a 48 h interval, and daily treatments for 3 d. Cell proliferation after plasma application was quantified in real time, and immunohistochemistry was used to establish the viability of the cells and determine changes in their physiology. It was established that the frequency of cell treatments is important for the outcome. In the samples treated with single plasma application and double plasma applications with a 48 h interval, a 42.6% and 32.0% increase was observed in the number of cells, respectively. In addition, there were no signs of deoxyribonucleic acid breaks immediately after plasma application. In contrast, plasma application increased the accumulation of cells in the active phases of the cell cycle. The activation of proliferation correlated with a decrease in the level of β-galactosidase, a senescence marker. This could be due to cell renovation after plasma application. Daily treatment decreased cell proliferation up to 29.1% in comparison with the control after 3 d.

Two-stage melting is observed experimentally in a confined monolayer of dust particles in plasma. The pair correlation and bond-angular correlation functions, the number of topological defects, and the pair potentials are measured and analyzed. The bond-orientational correlation functions show a clear solid-to-hexatic-to-fluid transition, in perfect agreement with the Berezinskii-Kosterlitz-Thouless transition theory.