Pointing out the structure of double layers through spectroscopic methods

Abstract

ABSTRACT The present paper investigates the dependence of local emissivity, for two spectrum lines of helium, upon the locationwithin a stationaiy double layer. The experimental results are explained starting from a new phenomenological model,which takes into account the non-elastic interactions between the accelerated electrons and the atoms ofthe working gas.Keywords: double layers, local emissivity, non-elastic processes, spectroscopic methods 1. INTRODUCTION In order to investigate the medium within double layers, the method of (electrostatic or emitting) probes is currently used'.As double layers are strongly influenced by the properties of the solid bodies that bound the ionised medium these areformed in, the displacement of the probe can determine significant alterations of the double layer parameters. It is for thisreason that the results provided by the methods based upon probes, in the field of double layers, must be regarded withreservation.Unlike the methods using probes, the optical methods have the essential advantage of not significantly perturbing thedouble layer. Obviously, the method of investigating the double layer structure through the analysis of the radiationemitted by the double layer does not allow the direct emphasising of the local physical parameters which charactense thedouble layer (the electric potential, electric charge densities, the average energy of the electrons, etc.). That is why theemphasising of the double layer structure through this method is in close connection to the theoretical model used forexplaining the appearance of this type of sell-organisation of matter. The present paper investigates the dependence oflocal emissivity, for two spectrum lines ofhelium, upon the location within a stationary double layer.