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The filamentation dynamics of a nitrogen pulsed microwave discharge generated at the antinode of a standing electromagnetic wave at a pressure of 100 torr has been numerically simulated. The results of the dynamics of the main plasma parameters, such as the concentration of charged and excited species, gas temperature, and vibrational temperature of nitrogen, are presented. [ABSTRACT FROM AUTHOR]

The paper is dedicated to the numerical study of the dependence of plasma antenna resonance wavelengths on pressure. The study was carried out by simulating a RF capacitively coupled plasma with the Comsol Multiphysics software in one- dimensional formulation. Based on the calculated electric current in the plasma, the directional pattern and axial distribution of the electromagnetic field were found by solving Maxwell's equations in a 2D formulation. The results showed that one of the advantages of plasma antennas is the transmission of waves at significantly longer wavelengths compared to metal antennas of similar geometry. [ABSTRACT FROM AUTHOR]

In this paper we developed a model of the ICRF plasma flow in a geometry of the two following regions: a plasma torch (narrow area) and a chamber (broad area). We used the numerical model developed in the COMSOL-multiphysics software with the given parameters of outlet pressure p = 133 Pa, drive power W = 1.3 kW, drive frequency f = 1.76 MHz and gas flow G = 0–0.4 g/s. We obtained the spatial dependencies of the electron density, electron temperature, pressure in the chamber, gas velocity and performed the analysis of effects in the broadening area. As a result, we noticed some features, which include an anomalous increase of the electron density in the broadening area. [ABSTRACT FROM AUTHOR]

A microwave discharge inside a bubble filled with microwave plasma in water and ethanol vapors at a pressure of 0.1 atm was simulated in the zero-dimensional approximation. The specific power absorbed by the discharge was used as a parameter. To describe processes in the discharge, reactions with charged particles for water, alcohol, and their decomposition products were added to the set of reactions developed for describing the thermal processes of combustion and detonation. The calculated concentrations of the main decomposition products of an aqueous ethanol solution were consistent with experimental data available in the literature over wide ranges of the feed mixture composition and power inputs to the discharge. [ABSTRACT FROM AUTHOR]

This work is devoted to simulating a microwave discharge in water and studying kinetic processes in a gaseous mixture of water decomposition products. Calculations have been performed for atmospheric and low pressure and a constant gas temperature. A one-dimensional model has been developed on the basis of the joint solution of the balance equation for neutral and charged plasma components, the Boltzmann equation, the equation for the stationary distribution of the microwave field in the plasma-filled volume, and the Poisson equation. Using the zero-dimensional model, an abridged kinetic reaction scheme for water vapor plasma was obtained, which was employed in the one-dimensional model. The calculations have been carried out for preset values of the microwave field. It has been shown that the modes of transition from electronegative to electropositive plasma obtained using the zero-dimensional model at E/N values above 350 Td are not observed in the case of the one-dimensional model of microwave discharge. In a wide range of microwave field values specified on the antenna, the microwave plasma in water is electronegative. The concentration of electrons is low in comparison with the concentration of positive ions H3O+, , and H3O+(H2O)3, quasi-neutrality is maintained by the negative ion OH−, and the degree of dissociation of water does not exceed 20–25%. [ABSTRACT FROM AUTHOR]

The paper presents the results of an experimental study on the oxidation of nitrogen in air in stationary and pulse microwave discharges at atmospheric pressure. The thermodynamic and physical characteristics of the process have been calculated, and its energy efficiency in these discharges has been analyzed on their basis. The possibility of obtaining NO with a low NO2 content for medical applications is demonstrated. [ABSTRACT FROM AUTHOR]

A self-consistent model has been formulated that describes microwave discharge in an argon/ethanol gas mixture. On the basis of this model, two-dimensional numerical calculations have been carried out to study the process of carbon synthesis in nonequilibrium microwave discharge plasma in an argon/ethanol gas mixture at atmospheric pressure for various values of input power. The formation of pure carbon and CH, CH2, and CH3 radicals is shown, and their distributions depending on the power input into the microwave discharge have been investigated. [ABSTRACT FROM AUTHOR]

A comparative study of the chemical composition and properties of poly(methyl methacrylate) and poly(ethylene terephthalate) after their treatment in various types of low-temperature oxygen plasma has been performed. It has been found that as a result of treatment, oxygen-containing functional groups are formed on the polymer surface, the content of which depends on the type of plasma and determines the increase in hydrophilicity of the polymer surface. The advantages of hybrid plasma generated by the simultaneous action of RF discharge and high-energy electron beam on the plasma-forming gas during the processing of polymers are discussed. [ABSTRACT FROM AUTHOR]

A zero-dimensional model is presented for a microwave discharge in liquid n-heptane at atmospheric pressure with continuous introduction of argon into the plasma region. The model includes equations describing the formation of a solid phase from n-heptane degradation products. Along with the detailed kinetics of thermal pyrolysis of n-heptane, processes involving argon atoms and processes involving electrons, ions, and excited species are included. To determine the electron energy distribution function, the Boltzmann equation is used. For comparison with the spectral characteristics of the discharge, the kinetic scheme includes the processes of excitation of the radiative states of the hydrogen atom and the C2 molecule. Calculations have made it possible to explain the appearance of Hα lines at sufficiently high concentrations of introduced argon. [ABSTRACT FROM AUTHOR]

The composition of liquid hydrocarbons (hexane, n-heptane, octane, isooctane, decane, benzene, toluene) has been studied by gas chromatography–mass spectrometry after exciting a microwave discharge in their volume at atmospheric pressure above the surface of the liquid with air bubbling. The composition of the hydrocarbons after treatment includes a wide range of products up to C40, with the product composition being different for different initial hydrocarbons. Optical emission spectroscopy showed the presence of CN bands in the emission spectra of the discharge. [ABSTRACT FROM AUTHOR]

Main gaseous products (H2, C2H2, C2H4, CH4) formed by microwave discharge in a number of liquid alkanes, cycloalkanes, and aromatic hydrocarbons have been studied using gas chromatography. It has been shown that the products of the discharge in these cycloalkanes and aromatic compounds bearing no side groups almost do not contain methane or ethylene, unlike the case of alkanes. [ABSTRACT FROM AUTHOR]

A mechanism for the degradation of n-heptane and the formation of the products of its plasma-chemical transformation by microwave discharge treatment has been proposed. Chemical reactions resulting in reactive species, namely free radicals that form lower hydrocarbons and polyaromatic structures are presented. The product composition of the gas, liquid, and solid phases has been studied using gas chromatography–mass spectrometry analysis of the precipitate obtained by evaporation of the liquid phase after the treatment of n-heptane. [ABSTRACT FROM AUTHOR]

Changes in liquid hydrocarbons (hexane, cyclohexane, n-heptane, isooctane, decane, pentadecane, cetane, petroleum solvent, benzene, toluene, and o-xylene) have been studied after exciting a microwave discharge in their bulk. The experiments have been carried out at atmospheric pressure. For the analysis, GC/MS, IR spectroscopy, and dynamic light scattering methods have been used. It has been shown that new compounds and nanoparticles are formed in the hydrocarbons. [ABSTRACT FROM AUTHOR]

The process of plasma-chemical conversion of germanium tetrafluoride in a radiofrequency discharge (13.56 MHz) has been studied. The dependences of the germanium yield on the specific energy input, the H/GeF molar ratio, and the total pressure have been measured. The maximum germanium yield is more than 95%. The minimum specific energy consumption at an energy input of 9 MJ/mol is 9.4 MJ/mol or 2.6 kW h/mol Ge. A mechanism of plasma-assisted reduction of germanium tetrafluoride under the given the experimental conditions has been proposed. [ABSTRACT FROM AUTHOR]

Microwave discharges in liquids represent a new direction in plasma physics and chemistry. Results of experiments on the recovery of metals from a liquid residue after vacuum distillation of the hydroconversion product of vacuum tower bottoms by treating the residue with microwave discharge initiated in its bulk at atmospheric pressure are presented. It has been found for the first time that the concentrations of Al, Co, Cu, Fe, Mo, Ni, V, and Zn metals in a treelike structure deposited on a microwave antenna are 10-20 times their concentrations in the substrate. [ABSTRACT FROM AUTHOR]

It has been found that a microwave discharge in liquid n-heptane leads to the formation of a solid phase in the form of carbonaceous nanoparticles. The composition and size of the particles have been determined by means of scanning electron microscopy with energy dispersive analysis and Raman spectroscopy. Using electronic absorption and luminescence spectroscopy, it has been shown that the discharge treatment results in the formation of polycyclic aromatic hydrocarbons in liquid n-heptane. [ABSTRACT FROM AUTHOR]

The process of plasma-chemical conversion of silicon tetrafluoride in a radiofrequency (13.56 MHz) discharge has been studied. The dependence of the yield of silicon on the specific energy input and the H/SiF molar ratio has been examined in the pressure range of 0.1-0.3 Tort. The maximum yield of silicon is 60%, and the optimal specific energy consumption is 44.6 MJ per mole of Si. A mechanism has been proposed for the plasma-assisted reduction of silicon tetrafluoride under the given experimental conditions. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the plasma-induced reduction of silicon tetrachloride with hydrogen microwave discharge. The study investigates the yield of hexachlorodisilane and conversion of silicon tetrachloride under gas chromatography. The study reveals that the yields of hexachlorodisilane and silicon depend on the energy input and the way of the reactants' delivery to the discharge zone.