INSTITUTE OF PHYSICS PUBLISHING PLASMA SOURCES SCIENCE AND TECHNOLOGY Plasma Sources Sci. Technol. 13 (2004) 95–107 PII: S0963-0252(04)67712-7 Plasma chemical and electrical modelling of a negative DC corona in pure oxygen C Soria 1 , F Pontiga 2 and A Castellanos 1 1 Departamento de Electr ´ onica y Electromagnetismo, Universidad de Sevilla, Av. Reina Mercedes s/n, 41012 Sevilla, Spain 2 Departamento de F´ ısica Aplicada II, Universidad de Sevilla, Av. Reina Mercedes s/n, 41012 Sevilla, Spain E-mail: cshoyo@us.es Received 1 August 2003 Published 20 November 2003 Online at stacks.iop.org/PSST/13/95 (DOI: 10.1088/0963-0252/13/1/012) Abstract A complex plasma chemical and electrical model of a negative stationary wire-to-cylinder corona discharge in pure oxygen is presented. The corona discharge is assumed to have axial and azimuthal symmetry. The experimental current–voltage characteristic is required as input data, but there are no other adjustable or empirical parameters. The experimental validation of the results of the model comes from its prediction of the ozone concentration. The role played by different reactions and species is analysed in detail using the results of the simulation. The effect of the gas temperature and of the decomposition of ozone at the electrodes is also investigated. The agreement between the model and the experiments is excellent when the effect of ozone decomposition at the electrodes is taken into account. 1. Introduction Corona discharge at atmospheric pressure has been used for a long time to charge surfaces [10], in electrostatic precipitators [27], and more recently in the removal of toxic components from industrial flue gases [35, 19]. The study of corona discharge involves both physical and chemical aspects. As expressed by Loiseau et al [24], simulation must cope with hydrodynamics, chemical kinetics and discharge itself. Numerous models of corona discharge have been proposed. In [20, 21] a wire-to-cylinder corona discharge is modelled by means of electronic injectors with azimuthal symmetry, assimilating the coaxial discharge to a succession of elementary point-to-cylinder electrical discharges. The temporal dependence of these electronic injections is given by an empirical law and the linear density of injectors is used as an adjustable parameter. Therefore, no electrical simulation is performed. Further refinements of the model include a radial temperature gradient [24]. Recent papers by Chen et al have focused on positive [6] and negative [7] DC coaxial corona discharge. In these studies, the ionization region is assumed to have azimuthal symmetry, and the corona discharge is modelled in terms of ionization coefficients. Also, the same authors have elaborated a complex two-dimensional simulation of ozone production in wire-duct devices with either positive [8] or negative polarity [9], considering a selected set of reactions. In this paper, a physical–chemical model of negative corona discharge in pure oxygen in presented. The discharge is considered as stationary in time and having azimuthal symmetry. In contrast with [20, 21, 24, 8, 9], no axial gas flow is considered here. Therefore, the corona discharge is assumed to have translational symmetry along the axial coordinate. The electrical and chemical aspects are simulated simultaneously. Consequently, Poisson’s equation for the electric potential is integrated together with the balance equations for species. Similarly, the geometrical simplicity of the system allows the inclusion of a large number of reactions, which means that selection of the probably relevant ones is not necessary. Processes between electrons and ions, electrons and neutrals and ions and neutrals are considered. The current–voltage characteristic is required as input data for the simulation, but there are no other parameters, neither empirical nor adjustable. The purpose of this study is to analyse the plasma chemistry and electrical behaviour of the corona discharge and, in particular, the production of ozone, without a priori assumptions. This paper has been preceded by others of lower complexity [28, 29]. Also, in this model, the effects of temperature and decomposition of ozone at the electrodes are included. 0963-0252/04/010095+13$30.00 © 2004 IOP Publishing Ltd Printed in the UK 95