Theoretical study of a plasma column sustained by an electromagnetic surface wave in the dipolar mode

This paper presents a theoretical model of a plasma column sustained by an electromagnetic surface wave in the dipolar (m =1) mode for two different gas-discharge regimes: free-fall/diffusion and recombination respectively. The dispersion characteristics of the wave and the axial profiles of the plasma density, wave power, wavenumber and wave-field components for a given regime are specified by one numerical parameter σ = ωR/C, where ω is the angular wave frequency, R the plasma radius and c the speed of light, irrespective of the gas nature and pressure. It is established that there exists a ‘critical’ value of this parameter, σ_cr = 0·3726, below which a plasma is not likely to be sustained. A comparison between the axial structures of plasma columns sustained by electromagnetic waves in the dipolar and azimuthally symmetric modes is made. The model is in agreement with the available experimental results.