Global Model of Plasma Chemistry in a High Density Argon/Hydrogen Discharge

Abstract

A mathematical Model is developed to evaluate the influence of operating parameters on hydrogen dissociation and the nature of the major species present in Ar/H2 plasmas. The Boltzmann equation is solved to obtain the electron energy distributions. Mass and energy conservation equations are then solved simultaneously to calculate the species density and electron temperature as a function of pressure, power, and feed composition. Good agreement is found between the model results and experimental measurements. The primary effect of argon addition to hydrogen plasma is to increase the electron density, which in turn enhances the degree of hydrogen dissociation. It is also found that Ar/H2 plasma retains the basic properties of hydrogen plasma even for feed gases containing more than 70% argon. That is, values of electron temperature and H-atom density are similar, and the dominant ionic species is H3+ ion.