Ionization equilibrium model for the multiply charged ion formation

Abstract

A model is proposed to study an argon plasma ionization equilibrium. Considering elastic collisions between electrons, ions and neutrals, it appears that ion-ion collisions are dominant among these processes. From an evaluation of the diffusion coefficient, it is then possible to express an ion life time τ zi which varies as Zi2 (Zi being the ionic charge state). Balance equations are then solved with values of electron number density, electron and ion temperatures as observed in E.C.R. ion sources (Electron Cyclotron Resonance ion sources). The charge state distribution calculated from the model is compared with published experimental results. The agreement is good. It is suggested that increasing electron number density and decreasing neutral gas pressure, all other parameters being kept constant, would allow creation of hydrogen like argon ions