A chemical non-equilibrium model of an air supersonic ICP

Abstract

A numerical model for an air inductively coupled plasma (ICP) torch with a supersonic nozzle is developed using reaction rates under chemical non-equilibrium. The reaction model takes into account 11 species (neutral species: N2, O2, NO, O, N and charged species: , , NO+, O+, N+, e−) in air ICP. The species distribution in the air inductively coupled thermal plasma with a supersonic nozzle is obtained by solving the mass conservation equations taking into account diffusion, convection and chemical reactions. The thermal conductivity, electrical conductivity, viscosity and diffusion coefficient are calculated at every step of the computational process using the method of Chapman and Enskog. The most recent sets of collisions integrals available in the literature are used, taking into account higher-order formulae to compute the electron transport properties.In this work, the deviation from chemical equilibrium (CE) is determined by comparing with the CE calculation result and is found to be very important. The influence of different order formulae to calculate the electron transport properties (electrical conductivity) on electromagnetic fields is also investigated and recommendations can be made according to the range of temperatures, powers and flow rates expected in the plasma torches.