Modeling of a plasma column produced and sustained by a traveling electromagnetic wave in the presence of a constant axial magnetic field.

Abstract

We present the basic equations for modeling a plasma column produced and sustained by a traveling electromagnetic wave in the presence of a constant external magnetic field. The model consists of two equations---a local-dispersion relationship and a wave-energy-balance equation---and a relation between the absorbed wave power per unit length averaged across the column (proportional to the squared-wave electric field) and the local electron number density. The dispersion relation and the balance equation are derived in explicit forms and depend on two numerical parameters \ensuremath{\sigma}=\ensuremath{\omega}R/c (\ensuremath{\omega} being the wave angular frequency, R the plasma column radius, c speed of light) and \ensuremath{\Omega}=${\mathrm{\ensuremath{\omega}}}_{\mathit{c}}$/\ensuremath{\omega} (${\mathrm{\ensuremath{\omega}}}_{\mathit{c}}$ is the electron cyclotron frequency). The limit of an infinite external magnetic field (\ensuremath{\Omega}\ensuremath{\rightarrow}\ensuremath{\infty}) is also considered. The influence of the two parameters \ensuremath{\Omega} and \ensuremath{\sigma} on the dimensionless axial profiles of the wave characteristics and plasma column density, obtained by numerical solution of the basic equations, has been studied for two different gas-discharge regimes. A three-dimensional wave structure has been obtained, and it is shown that the wave can be a generalized surface mode, a pure surface, or a pseudosurface one. The results obtained are in agreement with the available experimental data.