Modélisation électrique de la cellule par une méthode volumes finis

International audienceLa modélisation électrique de la cellule, et en particulier l'obtention de la tension transmembranaire, est un problème important en bio-électromagnétisme (électroporation). Dans ce cadre, une modélisation électro-quasi statique est utilisée pour décrire le problème sous forme d'équation de Poisson. Dans cet article, nous proposons une méthode basée sur les volumes finis pour résoudre numériquement le problème. Elle permet de prendre en compte les discontinuités de façon rigoureuse sur des maillages très déformés. La méthode est testée numériquement sur un modèle 2D d'une cellule circulaire (membrane et cytoplasme) soumise à un champ uniforme, puis à un champ électrique pulsé

Numerical Simulation of Back Discharge: Influence of Pinhole Geometry on the Regime Transitions

International audienceThis paper presents numerical simulation of back discharge activity that is modelled at a pinhole in a dielectric layer on plane anode. First, for a given pinhole geometry, the transitions between back discharge regimes have been depicted as a mode diagram. Then, we have studied the influence of the dielectric layer thickness on the regime transitions. We have shown that increase in the layer thickness (within range of 0.02\textendash0.2 mm) promotes the back discharge development. Finally, we have studied the influence of `crater configuration'. We have shown that `crater shape' favours the back discharge ignition, whereas limits the resulting discharge development

Electric field development in positive and negative streamers on dielectric surface

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A new one-dimensional moving mesh method applied to the simulation of streamer discharges

Streamer front propagation involves steep gradients in charge density and electric field. Since the front has to be meshed with a sufficient number of points, adaptive meshing is essential for fast and accurate numerical simulations. In this paper a one-dimensional (1D) moving mesh method recently developed by Tang and Tang (2003 SIAM J. Numer. Anal. 41 487–515) is successfully applied to the simulation of streamer discharge. One-and-half (1.5D) and two-dimensional (2D) simulations of streamer discharges in nitrogen at atmospheric pressure are presented. The moving mesh method is combined with the third order ULTIMATE QUICKEST scheme (Leonard 1991 Comput. Math. Appl. Mech. Eng. 88 17–74) to solve the advection part of the plasma continuity equations in a selection of classical problems in streamer simulation: point-to-plane and plane-to-plane electrode systems. The combination of the 1D moving mesh method and the high order scheme increases the accuracy of numerical solutions and reduces the computational time

The use of an improved Eddington approximation to facilitate the calculation of photoionization in streamer discharges

International audienceIn the simulation of streamer discharge propagation, classical integral methods used to calculate the photoionization source term are computationally very expensive. In this work, a new approach based on the direct solution of an approximate radiative transfer equation is developed. Different approximations of the radiative transfer equation are discussed and tested for typical conditions encountered in streamer discharges. An improved Eddington approximation is shown to be very accurate to calculate the photoionization term for a Gaussian emission source term with a half-width length of the order of 0.02 cm when the absorption coefficient of the gas is higher than or equal to 50 cm−1. For steeper gradients of the source term, good agreement is obtained for higher values of the absorption coefficient. Furthermore, the computation time of the improved Eddington method is four orders of magnitude less than with the usual integral method. For streamer propagation in air at atmospheric pressure, the absorption coefficient is shown to be of the order of 130 cm−1 which validates the use of the improved Eddington approximation to calculate the photoionization term. Finally, two-dimensional calculations of a positive streamer discharge in air at atmospheric pressure in plane–plane geometry with the improved Eddington approximation are presented

Measure of Electrical Parameters of Nanosecond Dielectric Barrier Discharges (nsDBD) in Air at Atmospheric Pressure

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Electrical measurements for Nanosecond Repetitive Pulsed Discharge

International audienceIn this paper, a device for accurate electrical measurements for nanosecond repetitive pulsed discharges (NRPDs) is presented. The experimental setup developed is based on an interelectrode system integrated in a transverse electromagnetic cell. This setup allows synchronizing the voltage and current measurements with a 4-GHz frequency bandwidth, corresponding to 250-ps pulse duration. A coaxial-shaped sharp metallic needle serves as a probe for current measurements. The needle probe is also the point electrode of a point-to-plane system used to generate discharges. The experimental setup was used to electrically characterize NRP corona and diffuse discharges, in negative polarity. Discharge current pulses with rise times less than 1 ns and amplitudes up to 120 mA were measured. The energy deposited by discharges was also determined

Numerical Simulation of Back Discharge Ignition

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