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This chapter is devoted to the analysis of electron-ionization and -elimination processes at early stages of electric-discharge development in air at altitudes of mainly 0–90 km. In this chapter, ionization processes in an external electric field, as well as background ionization by fast particles and electron attachment and detachment with participation of atomic and molecular oxygen, are considered. Temperature and concentration dependences of rate constants are described. Analysis of ionization models allowing simplified approaches to detailed computation models is undertaken. It is shown that the electric breakdown process in air, under the influence of an external electric field, comprises several stages that are different with respect to different altitudes over the Earth. Numerical modeling on the basis of a detailed plasma chemical model, taking into account the heating of gas by the discharge, has shown that the relaxation processes leading to gas heating also lead to the appearance of a nonlinear stage of electric breakdown. The considered phenomena can be convenient in the consideration of a high-altitude origination of natural discharges in fields of thunderstorm clouds.

Computer investigations devoted to hot filaments of streamer microwave (MW) discharge features and to shock wave (SW) (M ≈ 1.5) propagation through the MW filaments area have been made. Analysis of SW propagation through the hot filaments showed that there is a strong influence on SW, which leads to SW destruction at some filament forms and displacement. This shows a possibility of MW discharge hot filament applicability for technologies.

A plasma-aerodynamic model of the interaction of airflow and E-beam (EB) plasma has been developed. The results of the 2-D numerical simulation of the process of plasma jet generation under EB impact in air are presented. The complicated structure of plasma flow is caused by the nonuniformity of EB power put into the gas. The generation of active particles NO+ and NO takes place during the EB-flow interaction.

Studies of a plasma jet interaction with cross flows has been made for a development of a concept of plasma jets flow control application. A magneto plasma compressor is considered as a promising plasma jet, which parameters and characteristics are given. A computer simulation of a cross flow nitrogen plasma nitrogen jet from the divergent plasma generator has been carried out. This model involves a realistic equation of state, plasma radiation associated with plasma formation inside the plasma jet as well as coupling between the internal nozzle with external flow fields. Our model facilitates the application of the implicit free-Lagrange method for carrying out of computations, which have been carried out for jet injection angles 135° into the cross flow. These show the complex and non-homogeneous structure of the flow. They represent the necessary step in understanding of applicability of the plasma jets for a flow control.

NOx in exhaust gases of the airplane engine is considered. As a fuel were considered hydrogen and ethylene. Air arriving in the engine had static pressure and temperature corresponding to height of 20 km. Also considered questions of NO formation at electric fields origination near an aircraft.

Fundamental theoretical and computer investigations devoted to analysis of hot filaments of streamer MW discharge features and to shock wave propagation through the disturbed by MW filaments area has been made. This analysis includes: a) modeling of the hot fila- ment heating in dead air; b) modeling of SW (M=2) propagation through the hot filament; c) consideration of different filament forms and temperatures. Analysis has shown that rise of the filament temperature up to 2500-3000 K and producing of high concentrations of O and NO components can decrease ignition time of hydrocarbon fuel by hot MW filaments. Analysis of shock wave (SW) propagation through the hot filaments showed that there is strong influence on SW, which leads to SW destruction if long filaments directed in the same way as the SW. This shows the possibility of MW hot filament applicability for flow control.

Studies of plasma jet injection into a propane-air mixture counterflow have been performed regarding enhancing combustion and ignition by plasma jets. A computational model that we have used is discussed that involves a realistic equation of state, plasma radiation associated with plasma formation inside the plasma jet as well as coupling between the internal nozzle and external flow fields. A one-step effective propane-oxygen chemical reaction model with energy release was used for simulating ignition and combustion. Our model uses an implicit free- Lagrange method for the computations. Results of computations demonstrated ignition of propane-air mixtures stimulated by plasma jet generators each with a power of 15 kW. The incident propane-air stoichiometric mixture temperature was 1000 К. This concept can be applied for creation of quasi-planar jets in a real scramjet using a row of such plasma generators For analysis of ignition and combustion properties of the hydrocarbons in air it is necessary choose the key chemical reactions leading to them. The literature on propane combustion is rather vast and includes different approaches to combustion modeling 7-13