V. A. Titov

Simulation of the Processes of Formation and Dissociation of Neutral Particles in Air Plasma: Kinetics of Neutral Components

The results are given of calculations of the concentration of basic neutral particles and of the energy balance in an air plasma in the positive column of a d.c. discharge at pressures of 30 to 300 Pa and currents of 20 to 110 mA. The calculations are based on a combined solution of the Boltzmann equation; equations of vibrational kinetics for the ground states of molecules of N2, O2, and NO; and of the equations of chemical kinetics for these molecules, their excited states, and dissociation products. The results are compared with the measured concentrations of O(3P) atoms and NO molecules and with the effective vibrational temperatures of N2(X1Σ+g). The measured values of gas temperatures and temperatures of the reactor wall are used to find the fractions of energy transforming to heat in the plasma volume, which are compared with the calculation results.

Physicochemical and Engineering Problems in Studies on Plasma–Solution Systems

The example of an atmospheric-pressure glow discharge with an electrolytic cathode was used to show a significant role of the processes of transfer of solution components to the plasma zone, which were induced by ion bombardment of the surface of the solution. These processes not only determine the chemical composition of the plasma zone but also initiate redox reactions in the gas phase. In turn, the gas discharge alters the properties of the solution, in particular, its acidity, interfering with liquid-phase chemical reactions.

The characteristics of electrons and vibrational distributions of molecules in an atmospheric-pressure liquid-cathode dc discharge in air

Results are given of the calculation of vibrational distribution of N2, O2, and H2O molecules and of electron energy distribution functions in the plasma of atmospheric-pressure dc discharge with a distilled-water cathode. The system of equations of vibrational kinetics is solved simultaneously with the Boltzmann equation using the measured values of reduced electric-field strength, of discharge current density, of gas temperature, and of band intensities of the second positive system of N2 molecules.

The Simulation of the Processes of Formation and Decay of Neutral Particles in DC Discharge Plasma in an Argon-Oxygen Mixture

Results are given of calculations of concentrations of fundamental neutral particles in the positive column of a dc discharge in an argon-oxygen mixture. The calculations are based on simultaneous solution of Boltzmann equation, vibrational kinetic equations for the ground state of O2 molecule, and chemical kinetic equations for the ground and excited states of O2 molecules and Ar and O atoms with the experimentally determined value of reduced intensity of electric field E/N. The results are compared with measured values of radiation intensities of lines of 811.5 nm (Ar) and 845 nm (OI) and of atmospheric band O2(b1Σg+ → X3Σg−, 0-0).

The Treatment of Textile Materials in Air Plasma

The effect of treatment in an air glow-discharge plasma on a poly(ethylene terephthalate) film and fabric with different specific surface areas was examined. The rates of mass loss, oxygen uptake, and evolution of gaseous products (CO2 СО, H2O, H2) were measured over the pressure range 50–200 Pa at a sample temperature of 357 K. It was found that textiles with different textures had different specific etching rates. Possible reasons for this phenomenon are discussed.

Reaction of Oxygen Plasma Active Species with Polyethylene

The composition of the polyethylene surface upon treatment in an oxygen plasma and its afterglow was studied by attenuated total reflectance IR spectroscopy and X-ray photoelectron spectroscopy. The oxidation of the surface at the lowest destruction rates was attained upon simultaneous action of excited O2(a1Δg) and ground-state oxygen molecules. However, O(3P) atoms are involved in both the formation of oxygen-containing groups and their destruction accompanied by polymer degradation.

Influence of the Texture of Woven Materials on Their Etching Rate in Oxygen Plasma

The oxygen glow-discharge plasma treatment of a poly(ethylene terephthalate) film and fabric differing in their specific surface area was studied. The rates of mass loss, oxygen uptake, and gas evolution were measured over the discharge current and pressure ranges 20–110 mA and 50–200 Pa, respectively, at a sample temperature of 357 K. The specific etching and product formation rates calculated with accounting for the total surface area of fabric samples were shown to be not affected by the texture of studied materials.

The oxidative modification of polypropylene surface in electrolytic-cathode atmospheric-pressure discharge

The effect of electrolytic-cathode atmospheric-pressure discharge in air on the surface of polypropylene immersed in a solution and on the hydrogen peroxide formation efficiency was studied. It was found that iron(II) sulfate admixtures lead to a substantial increase in the concentration of oxygen-containing groups on the surface and to a decrease in the concentration of hydrogen peroxide in the solution. A possible interpretations of the results is given.

Physicochemical processes in the nonequilibrium plasma-polymer system

The results of investigation into interaction between nonequilibrium plasma and polymers, including the mechanism of generation of active species in a direct-current discharge in oxygen, air, and oxygen mixtures with argon, are reported, and the formation behavior of gaseous products of the reactions of these species with polymer is discussed. The influence of the gaseous products on the physical characteristics of plasma and the rates of the processes involving electrons is considered.

Effect of the Products of Plasma-Chemical Transformations on the Properties of a Plasma and Its Dynamic Behavior

A glow-discharge plasma bounded by a chemically reactive surface is studied. It is shown that the investigation of the properties of such systems must take into account heterogeneous reactions and chemical feedback. A study is undertaken to explore the dynamics of attaining the steady-state values of the discharge current and the plasma glow intensity in a case where there is gas desorption from the boundary surface. A formal model of the process is proposed that takes into account the accumulation of negative ions in the bulk of the positive column of the discharge. This model enables one to qualitatively explain the experimentally observed dynamic features of a plasma.