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Accueil > Séminaires & Soutenances > Séminaires, soutenances de thèses et HDR précédents > 2018 > Séminaires 2018 > Le jeudi 3 mai 2018 à 10h30

Le jeudi 3 mai 2018 à 10h30

Salle de réunion Jean Lascoux, aile 0, RdC

10h30 : accueil café

11h00 : Séminaire : "Interaction of helium plasma jets with surfaces"
par : N. Yu. Babaeva (Joint Institute of High Temperature, Russaion Academy of Sciences, Moscow, Russie)

Abstract :
Fig 1 : Evolution of forward and backward plasma bullets for a helium plasma jet.Atmospheric pressure plasma jets are often used as important tools for plasma processing, biotechnology, material science, surface functionalization and chemical conversion as well as in a relatively new area of plasma medicine. The jet plasma is often composed of so-called plasma bullets or ionization waves (IW). A conventional plasma jet consists of a dielectric tube or arrays of tubes with different electrode configurations outside or inside the tube. A noble gas with or without a small percentage of admixture gases is flowed through the tubes. Reactive species are generated in the discharge zone and carried by the gas flow to the treated surface. In this presentation, we will discuss results from the computational investigation of the effect of a conductive and dielectric targets on the plasma bullet propagation, reflection and evolution of the back bullet (Fig.1). We observed up to three bullet reflections from the target.

If time permits, we will also address computational studies of a streamer discharge. Computations are performed using Monte Carlo methods for simulation of high-energy electrons emitted from cathode surfaces. A negative streamer in air is initiated in a point-to-plane gap by applying high-voltage pulses of nanosecond duration. We analyze factors determining the transition to diffuse forms of the discharge. In particular, the structure of a streamer is presented calculated with and without account for the photoionization or pre-ionization by fast electrons. It is shown that diffuse discharges can be formed due to preliminary gas ionization by fast electrons.

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CNRS Ecole Polytechnique Sorbonne Université Université Paris-Saclay Observatoire de Paris
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Exploitant du site : Laboratoire de Physique des Plasmas, Ecole Polytechnique route de Saclay F-91128 PALAISEAU CEDEX
Hébergeur : Laboratoire de Physique des Plasmas, Ecole Polytechnique route de Saclay F-91128 PALAISEAU CEDEX
Directeur de la publication : Anne Bourdon (Directrice)

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