Trace chemistry modelling with DSMC in chemically reacting plasmas

Abstract

The Direct Simulation Monte Carlo (DSMC) method is a powerful method for modelling chemically reaction flows. It is a statistical method which simulates the Boltzmann equation by interacting computational particles which represent a large number of a single species type. A statistical problem can occur when trace concentrations are required to be accurately modelled; the traditional strategy is to use more computational particles per cell or simply obtain lower statistics and thus have higher uncertainty for the trace concentrations. We will present a method, based on an integral detailed balancing concept, which allows trace species chemistry to be efficiently modelled in the framework of DSMC. The test problem is a chemically reacting glow discharge plasma; the ion concentrations typically are at a 0.1% mole fraction but which dominant the physical mechanism for the system. Comparisons will be made to a chlorine plasma in a Gaseous Electronics Conference (GEC) reference cell with an inductive coil at approximately 20 mtorr system pressure.