Synthesis of Nitrogen Oxides in a Subthreshold Microwave Discharge in Air and in Air Mixtures with Methane

Plasma Physics Reports - A subthreshold discharge excited by a microwave beam in air at pressures close to atmospheric is studied as a plasmachemical method of nitrogen oxide (NOx) production. It...     

Simulations of the Formation of Nitrogen Oxides at the Cooling Stage of a Subthreshold Microwave Discharge in Air with Admixtures of Methane

Plasma Physics Reports - Studies of the composition of the products of chemical reactions in the afterglow of a new type of atmospheric discharge, the microwave self-non-self-sustained discharge in...     

Long-lived plasmoids generated by surface microwave discharges in chemically active gases

The generation of long-lived microplasmoids is observed during the irradiation of a metal-dielectric surface with a high-power microwave beam in a chemically active gas mixture (H₂ + O₂; CH₄ + O₂). The lifetime of these plasmoids substantially exceeds the characteristic recombination and cooling times of plasmoids arising at the target surface in a chemically inactive medium.     

A pulse-periodic torch in a coaxial waveguide: Formation dynamics and spatial structure

Results are presented from experimental studies of the formation dynamics, spatial structure, and parameters of a pulse-periodic microwave discharge excited in a coaxial waveguide. The experimental setup allows the stable generation of a plasma jet in molecular and atomic gas flows at pressures close to atmospheric pressure without applying additional initiators. The complicated sequence of processes leading to torch formation cannot be adequately described with conventional models of a discharge sustained by a surface electromagnetic wave.     

Conversion of methane in a coaxial microwave torch

A microwave coaxial plasmatron (microwave torch) is used as a plasmachemical converter of methane into hydrogen and hydrocarbons. The measured energy cost of methane decomposition is close to its minimum theoretical value. Such a low energy cost is unsurpassed for reactors operating at atmospheric pressure. A model of the plasmachemical converter is constructed. The results of calculations in the frame-work of this model agree well with experimental data.     

Ignition of a combustible gas mixture by a high-current electric discharge in a closed volume

Results are presented from experimental studies and numerical calculations of the ignition of a stoichiometric CH₄: O₂ gas mixture by a high-current gliding discharge. It is shown that this type of discharge generates an axially propagating thermal wave (precursor) that penetrates into the gas medium and leads to fast gas heating. This process is followed by an almost simultaneous ignition of the gas mixture over the entire reactor volume.     

Calculation of a coaxial microwave torch

Parameters of an equilibrium microwave discharge in an atmospheric-pressure argon flow in a coaxial waveguide with a truncated inner electrode are calculated numerically by using a self-consistent two-dimensional MHD model. The results obtained agree satisfactorily with the experimental data.     

Pulsed microwave discharge in a capillary filled with atmospheric-pressure gas

A pulsed microwave coaxial capillary plasma source generating a thin plasma filament along the capillary axis in an atmospheric-pressure argon flow is described. The dynamics of filament formation is studied, and the parameters of the gas and plasma in the contraction region are determined. A physical model of discharge formation and propagation is proposed. The model is based on the assumption that, under the conditions in which the electric fields is substantially below the threshold value, the discharge operates in a specific form known as a self-sustained-non-self-sustained (SNS) microwave discharge.     

Numerical analysis of a microwave torch with axial gas injection

The characteristics of a microwave discharge in an argon jet injected axially into a coaxial channel with a shortened inner electrode are numerically analyzed using a self-consistent equilibrium gas-dynamic model. The specific features of the excitation and maintenance of the microwave discharge are determined, and the dependences of the discharge characteristics on the supplied electromagnetic power and gas flow rate are obtained. The calculated results are compared with experimental data.     

A biresonant plasma source based on a gapped linear microwave vibrator

The operating principle of a novel microwave plasma source—a linear microwave vibrator with a gap—is discussed. The source is placed on a microwave-transparent window of a chamber filled with a plasma-forming gas (argon or methane). The device operation is based on the combination of two resonances—geometric and plasma ones. The results of experimental tests of the source are presented. For a microwave frequency of 2.45 GHz, microwave power of ≤1 kW, and plasma-forming gas pressure in the range 5 × 10⁻²–10⁻¹ Torr, the source is capable of filling the reactor volume with a plasma having an electron density of about 10¹² cm⁻³ and electron temperature of a few electronvolts.