Energy approach in the study of plasma structures of a high-pressure microwave discharge

Abstract

The energy characteristics of a plasma channel (filament) are the most important for a number of applications. A numerical study of the evolution of the thin plasma channel in air in the range of discharge parameters P = 30–750 Torr and λ = 2.3–8.5 cm showed that the total absorbed energy (Joule's losses) at each time instant is close to its upper estimate, which integrally depends only on the spatial distribution of the plasma density at this instant. A simple analytical expression is obtained for estimating the fraction of the wave beam energy transferred to the channel. An express method for estimating the energy characteristics of a plasma filament is proposed. The method is based on analytical expressions and experimental data on the temporal evolution of the plasma dimensions visible in photographs. The considered example shows the possibility of fast estimation of the total absorbed energy, as well as the specific energy and gas heating in the center of the channel during a microwave pulse.