The high-voltage field-emission driven nanosecond discharge in pressurized hydrogen is studied using the one-dimensional Particle-in-Cell Monte Carlo collision model. It is obtained that the main part of the field-emitted electrons becomes runaway in the thin cathode sheath. These runaway electrons propagate the entire cathode-anode gap, creating rather dense (∼10¹² cm⁻³) seeding plasma electrons. In addition, these electrons initiate a streamer propagating through this background plasma with a speed ∼30% of the speed of light. Such a high streamer speed allows the self-acceleration mechanism of runaway electrons present between the streamer head and the anode to be realized. As a consequence, the energy of runaway electrons exceeds the cathode-anode gap voltage. In addition, the influence of the field emission switching-off time is analyzed. It is obtained that this time significantly influences the discharge dynamics.

The mechanism of ethanol conversion in a nonequilibrium glow discharge has been studied. It is shown that molecular hydrogen is produced in reactions between ethanol molecules and hydrogen atoms in the initial stage and in reactions involving active H, CH₂OH, CH₃CHOH, and formaldehyde in the final stage. Comparison with experimental data shows that the kinetic mechanism used in these calculations correctly predicts the concentrations of the main components of the gas mixture.

In this paper, we seek to validate the zero-dimensional (global) model approach for the modeling of the plasma composition in high pressure reactive streamer discharges. We focus on streamers typical of dielectric barrier discharge that are widely used, for instance, for plasma-assisted reforming of greenhouse gases. However, our conclusions can be extended to the streamers used in plasma-assisted ignition/combustion and other related systems. First, we perform two-dimensional fluid simulations for streamers with positive and negative trigger voltages and analyze the difference between the breakdown mechanisms of these two modes. Second, we use the time evolution of the electron heating term obtained from the fluid simulations as the input parameter of the global model and compare the plasma component content predicted by this model with the results of the fluid model. We obtain a very good agreement between fluid and global models for all species generated in plasma. However, we conclude that streamers initiated by the positive and negative trigger voltage cannot be considered as symmetrical which is usually done in global models of barrier discharge reactors.

Iodine is being studied as an alternative propellant for electric propulsion application as it has numerous advantages over commonly used xenon gas. In spite of numerous experimental studies for the conditions typical for electric propulsion, there are very few computational modeling studies of iodine plasmas: all with reduced geometric representations in zero or one dimension. In the present paper, we use self-consistent two-dimensional fluid model coupled with Maxwell's equations to analyze the inductively coupled plasma generated in low-pressure iodine. We compare the plasma parameters for two values of the background pressure: 1.0 and 2.5 Pa. We find that ∼99% of the molecular iodine is converted into atomic iodine. As a result, plasma consists of electrons, ions I⁺, and a significant number of negative ions I⁻. The density of molecular ions I₂⁺ is much smaller than the density of I⁺. We analyze the transport of these species for two pressures and show that there are different regimes of plasma diffusion realized for the conditions of our studies. We also study how the discharge power influences the plasma parameters such as the electron and ion densities and the electron temperature.

The main aim of the present paper is to clarify the influence of the SF₆ fraction in the SF₆/N₂ mixture on the breakdown voltage. For this, the two-dimensional axisymmetric fluid model coupled with the comprehensive mechanism of plasma chemical reactions is used. In addition, the influence of various parameters such as the voltage rise time and the SF₆ fraction in the mixture is analyzed. It is observed that depending on the voltage rise time an admixture of only 1% of SF₆ to N₂ results in an increase in the breakdown voltage by 7%–43%. The sensitivity of breakdown voltage decreases with decreasing voltage rise time and is caused by the electron attachment time scale becoming comparable to the breakdown time. The results of simulations confirm that the increase in the SF₆ fraction in the mixture leads to an increase in the breakdown voltage. This is explained by the influence of the SF₆ fraction on the electron attachment rate coefficients rather than on the ionization reactions.

A multiphase computational model of atmospheric-pressure gas discharges ignited over liquid electrodes is developed. The model takes into account both the liquid electrode motion under applied electric fields and plasma generation in the gas phase. The influence of the applied voltage and liquid properties (density, viscosity, and surface tension) on the liquid surface deformation is analyzed. It is shown that the shape of dynamic cones formed on the liquid surface differs from the static Taylor's cones. The influence of the liquid surface protrusions on gas breakdown dynamics is demonstrated. It is shown that the breakdown develops in two stages: first, a fast ionization wave propagates from the cathode to the anode, and then the cathode sheath collapses due to secondary electron emission from the liquid surface. It is shown that dynamics of the multiphase system containing gas, plasma, and liquid states is characterized by three disparate time scales: the fast electron time scale, the intermediate ion time scale, and the slow liquid dynamics time scale.