Using chromatography, the gas composition in a cold plasma jet, which is a flowing afterglow of a microwave glow discharge at atmospheric pressure, is analyzed. The plasma jet is formed by the interaction of the discharge plasma with atmospheric air behind the outlet of the 6-electrode plasma torch, electrical power to which is supplied from the waveguide microwave (2.45 GHz) plasmatron. An analysis of the gas samples of the jet shows that when plasma-forming argon flows through the microwave discharge, hydrogen and methane are formed behind the discharge region, and the concentration of carbon monoxide increases by 5–6 times. The reactive oxygen species in the cold plasma jet is studied using liquid chromatography of an aqueous solution of isopropyl alcohol after treatment with the plasma jet. It is found that because of plasma treatment, partial oxidation of isopropyl alcohol to acetone occurs. This makes it possible to consider acetone as an indicator of reactive oxygen species (hydroxyl radicals, atomic oxygen and ozone) in a cold plasma jet.

The paper investigates the characteristics of the formation and morphology of microstructured zirconium oxynitride (ZrON) films, taking into account structural polymorphism during the impact of atmospheric-pressure microwave nitrogen plasma with the influx of active oxygen from the surrounding atmosphere. Optical, hydrophobic, Raman-active properties of ZrON films have been studied. X-ray diffractometry (XRD), scanning electron microscopy (SEM), ellipsometry method, and Raman spectroscopy, and moisture-resistance properties are used as analytical research methods. It is shown that during the short-term impact of microwave plasma, a morphologically heterogeneous ZrON film can be formed with a set of microhills with a uniform phase composition along the surface. The phase composition of the ZrON surface corresponds to the monoclinic structure of ZrO2. In the volume of the film, a predominantly tetragonal structure of ZrO2 is observed, as well as inclusions of the monoclinic structure of ZrO2. A mechanism for the formation of a ZrON film, taking into account polymorphism and phase transitions, is proposed. The optical properties of ZrON films are determined by both the dielectric phase of ZrO2 and the inclusions of the high-conductivity phase of ZrN. A combination of such factors as the developed microrelief and monoclinic surface structure, as well as nitride phase inclusions, enhance the hydrophobic properties of the ZrON film surface. It is shown that the surface hydrophobicity and resonant effects on ZrN inclusions allow for the enhancement of the Raman spectrum intensity due to the high concentration of analyte molecules in the scanning area.

The presented work studies the processes of synthesis of ZnO microstructures using atmospheric-pressure microwave nitrogen plasma and investigates their photocatalytic activity in the processes of degradation of 2,4-dinitrophenol and the antibiotic ciprofloxacin when irradiated with sunlight. The work proposes an effective method for formation of photosensitive ZnO powders. Due to the features of plasma treatment in the open atmosphere of zinc metal microparticles, ZnO structures are formed with sizes from hundreds of nanometers to several micrometers with various micromorphologies. The lattice parameters of ZnO structures are characteristic of a hexagonal unit with a = 3.258 Å and c = 5.21 Å, volume 47.95 Å3. The size of the crystallites is 48 nm. The plasma treatment was performed by means of a 2.45-GHz plasmatron at a power input of 1 kW in nitrogen flow at a rate of 1–10 L/min. Zn microparticles were injected into the microwave plasma at a mass rate of 20 g/min. High photoactivity was demonstrated (rate constants 0.036 min−1 and 0.051 min−1) of synthesized ZnO structures during photo-degradation of 2,4-dinitrophenol and ciprofloxacin, respectively, when exposed to solar radiation. Photo-active structures of ZnO synthesized using microwave plasma can find application in processes of mineralization of toxic organic compounds. Structures of ZnO synthesized using microwave plasma can find application in processes of mineralization of toxic organic compounds, and also in scintillation detectors, phosphors.

The spatio-temporal structure and plasma parameters of a new type of glow discharge—atmospheric-pressure interelectrode microwave discharge in gas flow—were studied experimentally and numerically. A multi-electrode coaxial-type cold plasma torch developed for large-area surface treatment was used as a gas discharge device. The torch was supplied with microwave power (2.45 GHz, ∼100 W) via a coaxial cable by a typical wave-guide plasmatron. Self-sustained glow discharges were excited between the round ends of the rod-like electrodes and inner wall of the cylindrical discharge chamber near the outlet. The filamentation of the discharge channel in the near-electrode regions was detected by high-speed video filming. The dendritic self-similar (fractal) character of the filaments’ structure was revealed and analyzed. The branching factor and fractal dimension of this structure were estimated as 3 and 1.1–1.3, respectively. Using discharge gas temperature T g = 1200 ± 100 K, as determined from the emission spectroscopy measurements, the following discharge plasma parameters were obtained from numerical calculations: electron temperature T e = 1.14 eV and concentration n e ∼ 10 21 – 10 22 m −3 , conductivity σ ∼ 400 Ω − 1 m − 1 , current density j ∼ 10 6 A m −2 , and electric field strength E ∼ 10 4 V m −1 .

The atmospheric-pressure cold plasma jet that is a flowing afterglow of the interelectrode microwave discharge in Ar was investigated using various diagnostic techniques. Waveguide-type 2.45-GHz-plasmatron with the external 6-rod-electrode plasma torch was used as the cold plasma source. High-speed shadowgraphy was used to obtain spatio-temporal structure of the cold plasma jet. The periodic character of plasma generation was studied using electric probe floating potential measurements with an oscilloscope.

Широкие перспективы использования нетермальной плазмы атмосферного давления (НТАП) связаны с ее огромным потенциалом уникальных технологических возможностей при создании новых продуктов и технологий. В данной статье представлены результаты экспериментального исследования параметров микроволнового источника НТАП, сочетающего в себе преимущества диэлектрического барьерного разряда и нетермальной плазменной струи.

Application of gas chromatography in analysis of a cold plasma jet generated by an atmospheric pressure microwave discharge in argon flow was considered. Previously developed 2.45-GHz-plasmatron with the external 6-rod-electrode plasma torch was used as a microwave plasma source. The analysis of gaseous samples showed that CO concentration increases by 5-6 times and new gaseous products appear – H 2 and CH 4 as a result of plasma-gas interaction. The production of CO, H 2 and O 2 occurs in the processes of dissociation of CO 2 and water vapor in the nonequilibrium plasma through the vibrationally excited states.

The measurements and analysis of the emission spectra both of atmospheric-pressure electrode microwave discharge in argon flow and cold plasma jet induced by the discharge are conducted. We used experimental setup based on the previously developed multipurpose 2.45-Hz-plasmatron with the external portable discharge chamber (plasma torch) with the outlet of 2.5 cm in diameter and power of about several hundred watts. Discharge chamber has 6 rod-like electrodes which form a regular hexagon in a cross section of the torch. Discharge channels are formed between the ends of the electrodes and the inner wall of the chamber. Molecular bands of NO, OH, N2, NH and atomic lines of Ar were found in the spectrum of the discharge channels. Based on the analysis of the spectra, it was shown that the gas temperature in the discharge channel was about 1200 K. In the cold plasma jet spectrum, due to its weak luminescence, only the molecular lines OH and N2 were reliably observed.

A cold atmospheric-pressure plasma jet was studied using the novel microwave plasmatron recently developed. Cold plasma jet was generated in Ar flow by electrode 2.45 GHz discharge of up to 200 W power in the portable plasmatron burner (torch) with 2.5 cm diameter outlet. Oscillograms and floating potential dependences on distance from the torch outlet were measured by planar electric probe. Axial and radial distributions of gas temperature in a cold plasma jet were obtained by means of thermocouple method.

Проведены измерения и анализ спектров излучения электродного СВЧ-разряда атмосферного давления в аргоне и генерируемой холодной плазменной струи.Для проведения исследований использовалась экспериментальная установка на основе разработанного ранее многоцелевого СВЧ-плазмотрона, работающего на частоте 2.45 ГГц, с внешней портативной разрядной камерой (электродной плазменной горелкой), имеющей выходное отверстие диаметром 2.5 см и мощность 200 Вт.Внутри разрядной камеры расположены 6 стержневых электродов, образующих правильный шестиугольник в поперечном сечении.При поджиге СВЧ-разряда разрядные каналы формируются между концами электродов и внутренней стенкой камеры.При этом разряды максимально приближены к выходному отверстию горелки.В спектре излучения плазмы в разрядных каналах обнаружены молекулярные полосы NO, OH, N 2, NH и атомарные линии Ar.На основе анализа спектров показано, что температура газа в канале достигает 1500 К. В спектре плазменной струи, вследствие её слабого свечения, надежно наблюдались только молекулярные полосы OH и N 2 .С помощью термопарных измерений показано, что температура газа в струе составляет около 100 0 С на расстоянии 2 см от выходного отверстия плазменной горелки.Анализ атомарных линий возбужденного аргона в эмиссионных спектрах, полученных в различных частях разрядного канала, позволил оценить электронную температуру в плазме СВЧ-разряда, которая составила от

Complex (dusty) plasmas of micron‐sized CeO 2 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)

In this work, the cryogenic dusty plasma, which is represented by a mixture of two dust components with different structural and dynamical properties, was experimentally investigated. Experiments were conducted in dc glow discharge at temperatures 10 and 77 K using CeO2 micron powder as a dust. In dust structures obtained one of the components consists of dust particles with chain-like ordering (dust chains) and another component consists of fast- moving particles orbiting horizontally through the first component (“crazy” particles). Dust particle velocity distribution functions were obtained. The possible reasons of two-component dust structure formation were discussed.

Formation of ordered structures from a large number (∼104) of charged diamagnetic macroparticles in a cusp magnetic trap under microgravity conditions is experimentally studied. The experiments are performed onboard the International Space Station. Dusty plasma structures in a cryogenic d.c. glow discharge (cryogenic dusty plasma) are examined. Ultrahigh charging of dust macroparticles under the action of an electron beam is experimentally obtained and studied. Results of an experimental investigation of various regimes of the Brownian motion of interacting dust particles in the plasma are presented. A method of determining particle interaction forces in nonideal systems with isotropic pair potentials is proposed. The method is based on solving an inverse problem that describes the motion of interacting particles by a system of the Langevin equations and allows reconstruction of parameters of the external confining potential without using a priori information about the friction coefficients of particles.

In the previous researches of cryogenic complex (dusty) plasma [1] we observed experimentally complex plasma systems formed in cryogenic environments. Particularly it was revealed from the experiments that dust structures with high concentration of macroparticles can be formed. So-called super dense dusty plasma structures in which interparticle distance is comparable with particle size were also observed. Thus concentration of particles was close to concentration of background plasma. Similar formations had unusual properties (sphere-like form, free boundaries, etc.) and represent new object in dusty plasma researches. In the present work new results on experimental investigations of dense dust structures at cryogenic temperatures were presented. The experiments were made by means of recently developed techniques and cryogenic facilities (optical cryostat). Possible nature of the unusual properties of super dense dusty plasma structures was discussed.

A model of the positive column of a DC glow discharge in argon with dust particles is presented. The model is based on the solution of the non-local Boltzmann equation for the electron energy distribution function (EEDF), the drift-diffusion equations for ions, and the Poisson equation for a self-consistent electric field. The radial distribution of dust particles density in a dust cloud is calculated according to an equilibrium Boltzmann distribution in the electrostatic field and under the action of the ion drag force. It is shown that if in the center of the discharge tube the ion drag force is larger than the electrostatic force, a dust-free region (void) in the central part of the dust cloud is formed. Otherwise (for a smaller ion drag force) the dust cloud is formed around the axis of the discharge tube without a void. In both cases, in the region of the dust cloud the ionization and recombination rates become almost equal to each other, and the radial component of the electric field is expelled from the dust cloud.

A self-consistent nonlocal model of the positive column of a dc glow discharge with dust particles is presented. Radial distributions of plasma parameters and the dust component in an axially homogeneous glow discharge are considered. The model is based on the solution of a nonlocal Boltzmann equation for the electron energy distribution function, drift-diffusion equations for ions, and the Poisson equation for a self-consistent electric field. The radial distribution of dust particle density in a dust cloud was fixed as a given steplike function or was chosen according to an equilibrium Boltzmann distribution. The balance of electron and ion production in argon ionization by an electron impact and their losses on the dust particle surface and on the discharge tube walls is taken into account. The interrelation of discharge plasma and the dust cloud is studied in a self-consistent way, and the radial distributions of the discharge plasma and dust particle parameters are obtained. It is shown that the influence of the dust cloud on the discharge plasma has a nonlocal behavior, e.g., density and charge distributions in the dust cloud substantially depend on the plasma parameters outside the dust cloud. As a result of a self-consistent evolution of plasma parameters to equilibrium steady-state conditions, ionization and recombination rates become equal to each other, electron and ion radial fluxes become equal to zero, and the radial component of electric field is expelled from the dust cloud.

must be given to the implementation of plasma applications in food technology and clinical practices.In a spirit of the workshop and in the terminology of microbiologists we wrapped up: regardless to our different backgrounds we should act like different members of the "biofi lm" (a very resistant microbial structure where various microorganisms mutually help each other to survive and to develop).Last but not least, the editors would like to appreciate the contributing scientists, researchers and students who traveled to Slovakia from around the world and made this workshop scientifi cally solid and socially warm.We would also like to recognize our colleagues and students from the Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava who contributed to the smooth organization of the event and provided the technical and IT support, especially Mário Janda.

The possibility of the formation of dust structures in cryogenic environment at 4.2‐77 K was proved experimentally in the previous researches of cryogenic complex (dusty) plasma [1–5]. It was revealed from the experiments, among others, that the dust structures with high concentration of dust particles can be formed, in which interparticle distance is comparable with particle size ‐ super dense dusty plasma structures. Such structures had exotic properties such as globular (spherical) form, free boundaries, etc. In the present work new results on the experimental investigations of new phenomenon of spheroidizing ‐ process of the dust structure transition to compact globular shape at cryogenic temperatures ‐ were presented. Possible nature of such phenomenon is discussed (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)