Numerical simulation of filamentary discharges with parallel adaptive mesh refinement

Direct simulation of filamentary gas discharges like streamers or dielectric barrier micro-discharges requires the use of an adaptive mesh. The objective of this paper is to develop a strategy which can use a set of grids with suitable local refinements for the continuity equations and Poisson's equation in 2D and 3D geometries with a high-order discretization. The advantages of this approach are presented with a filamentary discharge simulation in plane–plane geometry in nitrogen within the diffusion–drift approximation

The finite volume method solution of the radiative transfer equation for photon transport in non-thermal gas discharges: application to the calculation of photoionization in streamer discharges

International audienceThis paper presents the development of a direct accurate numerical method to solve the monochromatic radiative transfer equation (RTE) based on a finite volume method (FVM) and its application to the simulation of streamer propagation. The validity of the developed model is demonstrated by performing direct comparisons with results obtained using the classic integral model. Comparisons with approximate solutions of the RTE (Eddington and SP3 models) are also carried out. Specific validation comparisons are presented for an artificial source of radiation with a Gaussian shape. The reported results demonstrate that whatever the value of the absorption coefficient, the results obtained using the direct FVM are in excellent agreement with the reference integral model with a significantly reduced computation time. When the absorption coefficient is high enough, the Eddington and SP3 methods are as accurate and become faster than the FVM. However, when the absorption coefficient decreases, approximate methods become less accurate and more computationally expensive than the FVM. Then the direct finite volume and the SP3 models have been applied to the calculation of photoionization in a double-headed streamer at ground pressure. For high values of the absorption coefficient, positive and negative streamers calculated using the SP3 model and the FVM for the photoionization source term are in excellent agreement. As the value of the absorption coefficient decreases, discrepancies between the results obtained with the finite volume and the SP3 models increase, and these differences increase as the streamers advance. For low values of the absorption coefficient, the use of the SP3 model overestimates the electron density and underestimates the photoionization source term in both streamers in comparison with the FVM. As a consequence, for low values of the absorption coefficient, positive and negative streamers calculated using the SP3 model for the photoionization source term propagate more slowly than those calculated using the FVM

Plasmas Froids : Systèmes d'analyse, Modélisation et Rayonnement

I - Physique et applications atmosphériques des filaments de plasma générés par des impulsions laser ultrabrèves (Jérôme Kasparian, Jean Pierre Wolf) Spectroscopie d'émission optique sur plasma induit par laser : Principe et applications (Patrick Mauchien, Catherine Gallou, Jean Luc Lacour, Laurent Salmon) II-2. Spectroscopie de fluorescence induite par diodes laser : Application au diagnostic des plasmas (Stéphane Mazouffre) II-3. Un capteur de flux d'énergie dans les plasmas (A.-L. Thomann, N. Semmar, R. Dussart, L. Bedra, J. Mathias, Y. Tessier et S. Mazouffre) III-1. Modélisation de la photoionisation dans les plasmas d'air non-thermiques à la pression atmosphérique (Anne Bourdon, Sébastien Célestin, Julien Capeillère et Pierre Ségur) III-2. Modélisation des plasmas produits par interaction laser-matière (Tatiana E. Itina) IV-1. Propriétés et transferts radiatifs dans les plasmas (M.Y. Perrin, A. Soufiani, Ph. Riviere) IV-2. Modifications induites en surface de polymères par traitement laser (Patricia Laurens, Sophie Petit) IV-3. Lampes fluorescentes sans mercure, à la recherche de l'efficacité énergétique (Eric Robert, Sébastien Point, Sébastien Dozias, Christophe Cachoncinlle, Raymond Viladrosa et Jean Michel Pouvesle) IV-4. Sources plasmas de rayonnement X créées par laser (Fabien Dorchies) Importance du rayonnement dans les procédés thermiques industriels (Yann Cressault, Philippe Teulet, Jean-Jacques Gonzalez, Alain Gleizes) La spectroscopie optique appliquée à l'étude des disjoncteurs (Dunpin Hong, Jean-Marc Bauchire et François Gentils) Exemples de micro plasmas à haute densité : Électroérosion et ouverture de contacts électriques (Jean-Luc Dorier, Antoine Descoeudres, Christoph Hollenstein) Chauffage et génération de courant par ondes dans les tokamaks (Gérard Bonhomme