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ABSTRACT Modeling of the production of nitrogen oxide molecules in DC discharges in laminar longitudinal flows of atmospheric‐pressure air is performed. Two‐dimensional nonequilibrium discharge model includes the system of gas dynamic equations and balance equations for various plasma components. Simulations are performed for the discharge currents 50–600 mA and gas flow velocities 1–10 m/s. In considered conditions, the gas temperature in the discharge core varies in the range of 3000–6000 K. Spatial profiles of the densities and fluxes of produced species are obtained, both inside the discharge and in the afterglow region. The energy cost for the production of nitrogen oxides is calculated, depending on the discharge current, gap length, and gas flow velocity. The results of the simulation are compared with available experimental data. [ABSTRACT FROM AUTHOR]

In this paper, we report results from the computational study of the intersection of the atmospheric pressure plasma jet with a dielectric surface having high conductivity and high dielectric constant. In this case, multiple reflections of the ionization wave (IW) between the jet tube and the surface are observed. We consider the mixture of helium with a small percentage of oxygen (He/O2 = 99.8/0.2), which flows through the jet tube into the ambient humid room air (N2/O2/H2O = 79.5/20/0.5). We evaluate the production and delivery of main ions and reactive oxygen and nitrogen species, which are important for applications in biomedicine. The fluxes and fluences of these species to the dielectric surface are recorded during a single plasma jet pulse of negative polarity. We show that the electron density behind the IW front increases with each passage of the IW between the tube and the surface. With the forward, reflected, and secondary forward IW, there is an essential increase of ions and radicals behind the IW front. The highest increase of radicals and their fluxes is observed after the secondary forward wave bridges the gap and touches the surface. [ABSTRACT FROM AUTHOR]

The numerical results on naphthalene removal in biogas are presented and compared with experiment. Plasma-chemical processes in discharge and postdischarge stages are considered. The self-consistent approach for modeling of cleaning process on the basis of pulsed corona discharges is demonstrated. It has been revealed that the reaction of naphthalene ([C.sub.10][H.sub.8]) with excited nitrogen molecule ([N.sub.2]([A.sup.3][SIGMA])) is very important in the cleaning process in nitrogen-containing mixtures. The addition to [N.sub.2] of CO, C[O.sub.2], and [H.sub.2] results in the deterioration of treatment. Index Terms--Numerical simulation, plasma-chemical kinetics, streamer discharge, tar removal.

A model of atmospheric-pressure air discharges sustained by electromagnetic surface waves is developed that accounts for deviation of plasma state from the local thermodynamic equilibrium. Calculated distributions of plasma parameters along the discharge axis are presented for a wide wave-frequency range (from RF to microwaves). Values of the discharge length are given, depending on the wave frequency, the tube radius and the power input. It is shown that effects of ionization nonequilibrium become important at low values of the wave frequency and the discharge power. Parameters of microwave discharges in [N.sub.2]-[O.sub.2] mixtures, at small content of oxygen, are calculated and compared with available experimental data. Index Terms--Microwave discharge, high-pressure gas discharge, traveling electromagnetic wave, surface wave.

The results of two-dimensional numerical simulation of positive streamer dynamics in flue gases in sphere-plane electrode configuration are presented. The G-values (numbers of radicals produced per 100 eV of input electrical energy) for the production of chemically active particles participating in flue gas cleaning from toxic components are calculated. Obtained G-values are almost independent on the discharge conditions. Simple estimates for G-values, based on analytical streamer theory, are shown to agree with the results of numerical simulation. Index Terms - Corona discharge, flue gas cleaning, positive streamer.

A needle-circular electrode structure helium plasma jet driven by microsecond pulsed power is studied. Spatially resolved emission results show that the emission intensity of He(33S1) line decreases monotonically along the axial direction, while those of N2(C3Πu), N2 + (B2 Σ+ u), and O (3p5P) reach their maxima at 3 cm, 2.6 cm, and 1.4 cm, respectively. The plasma plume of the four species shows different characteristics: The N2 emission plume travels at a fast speed along the entire plasma jet; the N2 + emission plume is composed of a bright head and relatively weak tail and travels a shorter distance than the N2 emission plume; the He emission plume travels at a slower speed for only a very short distance; propagation of the O emission plume is not observed. Results of calculation of radiation fluxes emitted by positive streamers propagating along helium plasma jets are presented. It is shown, in agreement with the results of the present experiment and with other available experimental data, that the intensities of radiation of N2(C3Πu) molecules and He(33S1) atoms vary with time (along the plasma jet) quite differently. The factors resulting in this difference are discussed. [ABSTRACT FROM AUTHOR]

Results of simulation of streamers propagating along atmospheric-pressure air plasma jets formed by pulsed discharges in thin dielectric tubes are presented. The specific feature of these jets is substantial gas heating by the discharges. The hot gas, emerging from the tube, is cooled at mixing with surrounding air. The streamers are guided along the jet axis, the channel with reduced gas density. Spatial profiles of various plasma parameters inside the jet are calculated. The densities of produced oxygen and nitrogen atoms near the jet axis are one-two orders larger, while the widths of radial profiles of these species are several times smaller than those in typical helium plasma jets. [ABSTRACT FROM AUTHOR]