Atmospheric pressure plasma discharges : Physics and applications

International audienc

Modélisation électrohydrodynamique d'un réacteur plasma hors équilibre de dépollution des gaz

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Réalisation et caractérisation d'un réacteur plasma de laboratoire pour des études sur la dépollution des gaz d"échappement

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

3D streamer simulation in a point to plane configuration

International audienc

3D Simulation of a Point to Plane Air Corona Discharge

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SIMULATION OF THERMAL AND CHEMICAL RELAXATION IN A POST-DISCHARGE AIR CORONA REACTOR

International audienceIn a DC point-to-plane corona discharge reactor, the mono filamentary streamers cross the inter electrode gap with a natural repetition frequency of some tens of kHz. The discharge phase (including the primary and the secondary streamers development) lasts only some hundred of nanoseconds while the post-discharge phases occurring between two successive discharge phases last some tens of microseconds. From the point of view of chemical activation, the discharge phases create radical and excited species located inside the very thin discharge filaments while during the post-discharge phases these radical and excited species induce a chemical kinetics that diffuse in a part of the reactor volume. From the point of view of hydrodynamics activation, the discharge phases induce thermal shock waves and the storage of vibrational energy which relaxes into thermal form only during the post-discharge phase. Furthermore, the glow corona discharges that persist during the post-discharge phases induce the so called electrical wind. In the present work, the post-discharge phase is simulated in a bi-dimensional geometry using the commercial FLUENT software. The discharges effects (radical and excited species creation and thermal relaxation) are involved through chemical and energy source terms calculated from a complete 2Drz streamer model already developed

Arcing in ambient air triggered by pulsed x-ray radiation

International audienceThe generation of arcs in air at atmospheric pressure induced by static voltage and triggered by x-ray pulses is analyzed. A static voltage is set between a cathode and an anode, and the arcing process is triggered by irradiating the air gap of a pin-to-plane switch with an x-ray photon pulse in the MeV range. This x-ray pulse produces a weakly ionized non-equilibrium air plasma (called the pre-plasma), which reduces the breakdown threshold. The influence of this pulsed x-ray on the arcing process is analyzed. The reduction of the breakdown voltage has been quantified, and for low static voltages, the creation of a sheath that is responsible for a delay in the arcing process is highlighted. Electrical measurements (currents and voltages) and optical emission spectroscopy have been performed to characterize the arcs in terms of electron density, temperature, and electric conductivity. A good agreement between measurements and 3D Maxwell calculations is achieved, which allows us to determine the electric conductivity of the arc in both self-triggered and x-ray-triggered regimes

Effects of numerical and physical anisotropic diffusion on branching phenomena of negative-streamer dynamics

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