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Accueil > Séminaires et conférences > Séminaires, soutenances de thèses et HDR précédents > 2017 > Séminaires 2017 > Le vendredi 8 décembre à 10h30

Le vendredi 8 décembre à 10h30

Lieu : Salle de réunion du CPhT, bâtiment 6, à droite après le patio (+visio Jussieu, salle 509)

10h30 - Accueil café

11H00 - Séminaire

Orateur : Nikolay POPOV, Moscow State University (Skobeltsyn Institute of Nuclear Physics)

Titre : Fast gas heating in air plasmas : kinetic mechanism and effect on discharge constriction

Résumé :
Discharges at high electric fields are characterized by significant part of energy spend to excitation of electronically excited levels. At moderate and high pressures, the relaxation of electronically excited species leads to fast, within nanoseconds and tens of nanoseconds, energy release, so-called fast has heating (FGH). The rate of FGH can be as high as thousands kelvins per hundreds of nanoseconds. The fast gas heating is an important physical effect for a lot of application connected to chemically active plasma (plasma-assisted combustion, plasma conversion) and to flow control. Model of fast gas heating at different reduced electric fields will be presented ; the role of the FGH in streamer-to-leader transition in air in the pressure range 0.3-1 atm will be demonstrated. Recently observed effect of non-thermal contraction of nanosecond discharges at nanosecond time scale and discharge parameters at elevated pressures - discharge radius before and after contraction, discharge current, electron density - will be presented. The role of “nanosecond contraction” of discharge channel as the main mechanism of the discharge transition from glow to spark mode at high pressures will be discussed.


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Tutelles : CNRS Ecole Polytechnique Sorbonne Université Université Paris Sud Observatoire de Paris Convention : CEA
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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 : Pascal Chabert (Directeur)