In this work, on the basis of a unified model from the point of view of describing the gas discharge gap and electrodes for 2D geometry, numerical calculations were carried out to study various modes of direct current discharges in argon at atmospheric pressure. The influence of the cooling conditions of the electrodes on the current–voltage characteristic of the discharge is shown: the transition from normal glow to arc discharge with the formation of an abnormal glow mode and without it. It is shown that, depending on the cooling conditions of the electrodes, two forms of arc discharge can be obtained: with a diffuse or contracted current spot. In the low-current mode, current and voltage oscillations were obtained during the transition from the Townsend to the normal glow discharge.

A self-consistent unified model of direct current (DC) gas discharges in molecular gases describing the processes both in the discharge gap and in the electrodes is developed. Numerical simulations of the formation of parameters of various modes of DC discharge in nitrogen at atmospheric pressure in a wide range of current densities have been carried out in the one-dimensional approximation. As a result of numerical experiments, the dependence of voltage drop across the discharge on current density is obtained, which describes various discharge modes: from Townsend through normal and abnormal glow to arc discharge. The distributions of the main mechanisms of heating the electrodes, the values of their temperatures at the boundary with the discharge, depending on the current density, and all plasma parameters for various modes of a dc discharge are presented. It was shown that in the plasma region the dominant role in gas heating belongs to vibrational-translational relaxation, as well as to the reactions of dissociation of N₂ molecules by electron impact and quenching of electronically excited N₂ molecules. In the cathode layer, the dominant role in gas heating belongs to Joule heating by ion current. The scenario of formation of an arc discharge with free cathode mode when electrons are the predominant charged particles in the cathode layer was shown.

The method of plasma electron spectroscopy (PLES) is further developed for the analysis of impurities of organic molecules and ammonia in this work. In particular, for the first time the PLES method was used to detect the hydrocarbons impurities: alkanes (methane) and alkenes (ethylene), as well as their derivatives alcohols (ethanol), radicals, and ammonia. As the energies of the registered characteristic electrons are different for different chemical compounds, an important advantage of the PLES method is the fact that it allows simultaneous (in one measurement) registration of various impurities. This work presents a prototype of a PLES-gas analyzer based on nonlocal plasma of negative glow of a short glow discharge in helium.

The effect of the shape of the feeding voltage on the spatiotemporal characteristics of an atmospheric- pressure barrier microdischarge in argon is demonstrated using numerical simulations based on...