Speeding up fluid models for gas discharges by implicit treatment of the electron energy source term

Numerical fluid models are widely used in gas discharge physics. A typical dis charge model comprises continuity equations and drift-diffusion equatio ns for reactive particle species, a balance equation for the electron energ y, and Poisson's equation for the electric field. When this system of equat ions is integrated numerically with respect to time, the explicit evaluatio n of coupled quantities necessitates strong time step restrictions, resulti ng in an enormous slowdown of the calculation. The strongest time step rest riction arises from an explicit treatment of the coupling between the charg ed particle transport and the space charge field. In order to circumvent th is constraint several implicit and semi-implicit techniques have been devel oped. When one uses these techniques, however, the explicit handling of the dependence of electron energy source term on the electron mean energy beco mes limiting for the time step. In this work we present a technique for the implicit treatment of the electron energy source term, based on linearizat ion with respect to the electron mean energy. This approach makes it possib le to increase the time step by several orders of magnitude, thus giving a tremendous speedup of the calculation. Test results are provided for some t ypical cases, covering a wide range of numerical conditions. (C) 2000 Acade mic Press.