Aerosol dynamics in a sputtering DC discharge

Abstract

An aerosol sectional model that describes the space-time evolution of the size distribution of carbon particles produced in a graphite cathode sputtering discharge is presented. The model includes the coupled phenomena of particle growth processes, due to coagulation and molecular surface deposition, particle nucleation as inferred from a molecular growth process, particle charging in the plasma, and particle drift-diffusion transport in the electrode gap. Comparison between simulation results and experiments showed that the model yields a satisfactory prediction of the particle cloud density and particle mean diameter in the electrode gap. It also yields a satisfactory prediction of the particle size distribution. The calculated size distribution shows two particle-populations: a first one with a very small size and just above the nucleus diameter and a second population, with a larger size, that determines the mean-diameter of the particle cloud. The sectional model also shows that simple aerosol models assuming single size particles significantly overestimate the particle density although it yields a satisfactory prediction for the particle size.