Global model of plasma chemistry in a high density argon/hydrogen discharge

A mathematical model is developed to evaluate the influence of operating pa rameters on hydrogen dissociation and the nature of the major species prese nt in Ar/H-2 plasmas. The Boltzmann equation is solved to obtain the electr on energy distributions. Mass and energy con servation equations are then s olved simultaneously to calculate the species density and electron temperat ure as a function of pressure, power, and feed composition. Good agreement is found between the model results and experimental measurements. The prima ry 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/H-2 plasma retains the basic properties of hydrogen plas ma 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 H-3(+) ion.