Role of the fast atoms, ions and metastable Ar atoms in a HCD by means of an hybrid model.

摘要

The role of the fast neutrals, ions and metastable Ar atoms in a cylindrical HCD with operating parameters typical of those used in spectrochemical analysis is studied based on a self-consistent model. The model comprises sub-models based on the principle of Monte Carlo and fluid simulations. With Monte Carlo models the movement of the fast electrons, fast atoms and fast ions as particles is described, while with the fluid models; the slow electrons, ions and metastable atoms are treated as a continuum. The continuity equations for charged particles are solved together with the Poisson equation in order to obtain a self-consistent electric field. In the fluid model for the Ar metastable different production and loss mechanisms, responsible for the Ar metastable atom density, are considered. These models are run iteratively until convergence is reached. Typical results are, among others, the fast atoms, fast ions and fast electron excitation and ionisation rates, the electron, ion and metastable densities and fluxes, the energy distribution function for the fast atoms, fast ions and fast electrons, the electric field and potential distribution. Also the relative importance of different processes determining the metastable density in a Ar HCD is analysed, as well as the influence in the discharge properties of the fast atoms and fast ions collisions.