Nonequilibrium discharges in various liquids have been the object of intensive research in recent decades [1,2].Microwave discharge is an effective means of conducting plasma chemical reactions in liquid media.This paper presents the results of modeling and experiments in a microwave discharge in methane, which flows into the water through the tube of the central electrode-antenna.The discharge is a sequence of bubbles growing at the end of the antenna electrode, which, having reached a certain size, break away from the electrode, float up and collapse on the surface of the water.After separation from the electrode, the discharge in the bubble stops, and the bubble with products, formed as a result of plasma-chemical processes, rises to the top.Chromatographic analysis of the composition of reaction products has been carried out.During the simulation, the kinetics of processes is studied in the bubble, the volume of which is calculated at each time step.For each species, the equation of the balance of the number of particles is solved.The expansion of the plasma bubble occurs due to the following processes: the presence of a constant flow of methane through the supply tube; evaporation of the surrounding water into the plasma bubble; changes in the total number of particles due to plasma-chemical processes; changes in plasma temperature due to chemical reactions and ohmic heating.The thermal conductivity equation is used to calculate the gas temperature of the plasma.It is also assumed that all microwave power is spent exclusively on heating plasma electrons.The simulation allows us to determine the characteristic growth time of the bubble until its complete separation from the electrode.The characteristic reduced field at the moment of bubble separation reaches values of 30-40 Td with a power absorbed by the plasma of 200 watts.The main plasma ions are C 2 H 2 + and OH -.The main decomposition products are hydrogen and carbon monoxide.The agreement of the simulation and experiment results is satisfactory.The work was carried out within the framework of the TIPS RAS state program.

A microwave discharge inside of a methane bubble in boiling water is modeled in a 0D approximation taking into account the change in the size of the plasma bubble. The process of quenching the reaction products after the bubble detaches from the electrode surface is also simulated. The working pressure is 1 atm. It is shown that the main reaction products are H2, CO2, and CO. The ratio of CO2 and CO concentrations depends on the ratio of the initial flows of water vapor and methane. The calculated concentrations of the main decomposition products of methane and water are in good agreement with experimental data.

Gas chromatography was used to study the products of an atmospheric pressure microwave discharge in water with methane bubbling at incident microwave power ranging between 500 and 650 W and methane flow rate ranging between 25 and 75 mL/min. The main components of products are H2, CO, CO2, and CH4. The concentration of H2 reaches 75% with the energy consumption for hydrogen formation of 25 L/kWh. A zero-dimensional self-consistent nonstationary discharge model, which takes into account the process of quenching of reaction products, was developed to analyze experimental results and study mechanisms of the formation of hydrogen and carbon oxides. Taking into account the quenching of reaction products is an important and necessary part of modeling discharges in liquids. Microwave plasma in liquid hydrocarbons is the new area of plasma physics and plasma processing. In this article, we focus on the study of hydrogen production in microwave discharge in water with methane bubbling. This process is similar to so-called methane steam reforming. The process is studied using gas chromatography and optical emission methods and a specially designed zero-dimensional self-consistent model. This model includes the stage of quenching the products of reactions. Mechanisms of main gas products (H2, CO, and CO2) were determined. image

A zero-dimensional steady-state simulation of microwave discharge in water vapor at atmos-pheric and reduced pressures and a constant gas temperature has been carried out. A model of a continuous stirring reactor is used. A joint solution of the balance equations for neutral and charged plasma components, the Boltzmann equation for plasma electrons, and the equation for the stationary distribution of the microwave field in a volume filled with plasma is carried out. The dependences of various parameters of thedischarge (the magnitude of the microwave field, the concentrations of all components) on the input specific power WVare obtained. It is shown that at reduced pressure the magnitude of the microwave field in the plasma is signifi-cantly lower, and the electron concentration is higher than at atmospheric pressure at the same applied specific power. At atmospheric pressure the water plasma is electronegative, and quasi-neutrality is maintained by the negative OH-ion in the range of the considered WV values. Transition from electronegative to electropositive plasma occurs at pressure of 30 Torr and ap-plied specific power of 60–70 kW/cm3

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.

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+, $${{{\text{H}}}_{5}}{\text{O}}_{2}^{ + }$$ , 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%.

The influence of solid particles produced in plasma of microwave discharge in liquid n-heptane at atmospheric pressure on the electron energy distribution functionand detailed analysis of ion composition of plasma are presented.

It is shown that the soil is a mineral petrographic facie of endogenous-exogenous oil and gas bearing lithocomplexes of mud volcanoes in the South Siberian region, which belong to the fluid-dynamic systems of modern Earth degassing pipes. The fluid-dynamic regime of the latter determines wide variations of thermodynamic, physic-chemical, and geochemical conditions of soil formation. It has been established that mineral associations are formed thousand can be used as soil-genetic indicators. A number of the mineral paragenesis of soil formation fluid-dynamic conditions is identified: fluid-pyrometamorphic one, appeared during recovered gases strong oxidation and natural cracking of liquid oil; fumarolesteam gasous one; heterogenization products of hot springs hydrotherm; hydrothermal-sedimentary chemogenic one involving bacterial communities.

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 C 2 molecule. Calculations have made it possible to explain the appearance of H α lines at sufficiently high concentrations of introduced argon.

A zero-dimensional non-stationary model of a microwave discharge in liquid n-heptane at atmospheric pressure with continuous argon injection into the plasma region is presented. The model includes equations for the kinetics of neutral and charged plasma components, equations describing the formation and growth of solid particles from the decomposition products of n-heptane, and an equation for the microwave field strength in plasma. The description of the coagulation process takes into account the electrostatic repulsion of solid particles due to their charge. The kinetics of charged particles is described taking into account their death on the surface of negatively charged solid particles formed in plasma. To determine the coefficients of the reaction rates in mechanisms of direct electron impact, the electron energy distribution function obtained by solving the Boltzmann equation is used. Calculations have shown that the plasma quasineutrality is mainly supported by the charge of solid particles, and the electron concentration is 1–2 orders of magnitude less than the total ion concentration. An increase in the averaged microwave field was noted in comparison with the case that does not take into account charging. Charging of the solid particles does not affect the composition of the main gas-phase products, but leads to the suppression of the coagulation process for large solid particles, which leads to a change in the size distribution function of the solid particles formed in the plasma.

The effect of a small nitrogen additive on a microwave discharge in hydrogen ignited near the antenna at a pressure of 1 Torr was studied by emission spectroscopy and visualization methods. It is shown that, in the presence of a nitrogen additive, the discharge shifts along the antenna toward the generator and the intensities of hydrogen spectral lines and bands near the antenna decrease. These results are qualitatively explained on the basis of the earlier 1D simulation of the discharge. The changes in the discharge parameters are caused by the replacement of the light $${\text{H}}_{3}^{ + }$$ ion in hydrogen plasma with the heavy N2H+ ion in a discharge in a hydrogen–nitrogen mixture. As a result, the rate of diffusive particle loss decreases, so that the discharge can exist in regions with a weaker microwave field.

Main gaseous products (H 2 , C 2 H 2 , C 2 H 4 , CH 4 ) 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.

Microwave plasma in the liquid is initiated inside a gas bubble formed at the end of the electrode-antenna, through which microwave energy is introduced into the liquid. A 1D model a set of gas phase kinetic reactions describes the evolution processes of ionization, heat transfer and formation of gas and solid products inside the plasma bubble. The code is based on joint solution of the Boltzmann equation for free electrons of the plasma, a simplified equation for the microwave field, the heat conduction equation, the balance equation for the electron density and the balance equations for the weight fraction for all gas and solid products of n -heptane pyrolysis. The Joule heat released in the plasma is expended on the evaporation of liquid n -heptane into the bubble and the decomposition of the n -heptane molecules. The model includes both the description of gas phase processes and formation of solid carbon-containing particles. The growth mechanism for generation of solid particles describes simultaneous processes of the initial nucleation, surface growth and coagulation of soot particles. The results of calculations are compared with known experimental results.

A mechanism is proposed for the formation of hydrogen peroxide in an electrolyte-cathode atmospheric-pressure direct-current discharge. A local increase in the temperature of water in the area of liquid contact with the gas discharge causes its boiling, and strong electric fields due to unevenness of the turbulent surface appear on the splashes. As a result, a local breakdown of the hemispherical region of boiling water beneath the electrolyte-cathode spot is possible. The kinetic scheme of the reactions for water vapor plasma has been considered, and hydrogen peroxide concentrations have been calculated, the calculation results being in satisfactory agreement with experimental data.

A 0D model of time dependent processes, occurring in a gas bubble created by a microwave discharge in liquid n-heptane, is presented. The model includes both the description of gas-phase processes and formation of solid carbon-containing particles at atmospheric pressure. Two mechanisms of generation of solid particles are considered. The first one relates to the 'linear PAH growth model' and the second to 'planar PAH growth model'. Both of them describe simultaneous processes of the initial n-heptane pyrolysis and nucleation, surface growth and coagulation of soot particles. The results of calculations are compared with known experimental results. It is concluded that the second model describes the results of the experiments better.

Реликтовые минералы платиновой группы (МПГ) впервые обнаружены в нефрите тремолит-диопсидового состава, генетически связанного с дайкой бонинитов Горлыкгольского месторождения, приуроченного к отрезку зоны серпентинитового меланжа в южной части Оспинско-Китойского массива ультрабазитов Восточно-Саянского офиолитового пояса. Диагностированы микро-, нанофазы МПГ: рутениридосмин с примесью Ni, Fe, рутений, рутенистый Ir, иридоарсенит, омеит, лаурит. Источник МПГ – хромшпинелиды из гарцбургитов и дунитов Оспинско-Китойского массива, подвергнутые деформационным преобразованиям в зоне серпентинитового меланжа.