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 o. =coR /c (co being the wave angular frequency, R the plasma column radius, c speed of light) and A=co, /co (co, is the electron cyclotron frequency). The limit of an infinite external magnetic field (Q~~) is also considered. The inhuence of the two parameters 0 and cr 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.

Axial structure of plasma column sustained by non‐symmetric electromagnetic surface wave

“…In such consideration the dimensionless plasma density N in the region just near to the generator can be determined from the phase diagrams for the fixed azimuth wavenumber m and dimensionless parameters σ and Ω. The used discharge model allows one to compare the axial plasma density profiles of the discharges, sustained by the waves with arbitrary azimuth wavenumber m. It is necessary to mention that axial profiles of plasma density in the discharges sustained by the waves in symmetric (m = 0) and dipolar (m = −1) modes determined by means of this model are in good agreement with the results obtained by other research groups (see, for example, [5,7,8]). Also it is necessary to stress that this consideration is valid when axial variations of plasma density n, axial wavenumber k 3 and wave field amplitudes are slow enough to consider the locally uniform approximation.…”

“…The increase of external magnetic field value leads to considerable growth of the dimensionless plasma density and dimensionless discharge length, especially in the second stability region. Similar influence of external magnetic field on plasma parameters can be observed in gas discharges, which are sustained by the SW in dipolar mode [5,7,8]. It is necessary to mention that with the increase of external magnetic field value Ω the length of the discharge in the second stability region substantially exceeds the length of the discharge in the first stability region at the same external discharge parameters (approximately in four times for Ω = 3.0, see Fig.…”

“…There are some common approaches in theoretical description of such discharges which differently simplify the problem [2]. Current study was carried out in the framework of electrodynamic approach that consists in detailed analysis of SW characteristics (phase characteristic, attenuation coefficient, wave energy transport) while plasma elementary processes are taken into account only in simplified manner [5,6,7,8]. The experimental data show [9] that axial distribution of plasma density in gas discharges sustained by symmetric (m = 0) and dipolar (m = ±1) SW is well described by means of theoretical models based on the electrodynamic approach [5].…”

Azimuthally symmetric pseudosurface and helicon wave propagation in an inductively coupled plasma at low magnetic field

“…In the limit of infinite B field, all waves become TM modes, whatever the mode number is, and can be identified as a pure pseudosurface wave or volume waves. 9 Benova et al 10 recently calculated the three-dimensional surface and pseudosurface waves structure numerically for finite B field. They used an electromagnetic model consisting of a dispersion relation and an energy balance equation.…”

Electrodynamic Model of the Gas Discharge Sustained by Azimuthal Surface Waves

“…The gas discharges produced and sustained by electromagnetic waves propagating along the axial direction in the discharge chambers with cylindrical geometry are investigated both in the isotropic [2][3][4][5][6] and in the magnetoactive waveguides [7][8][9][10]. It is found that application of the external magnetic field facilitates the plasma production and makes the discharge region longer [8].…”