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Accueil > Séminaires & Soutenances > Séminaires, soutenances de thèses et HDR précédents > 2019 > Séminaires 2019 > Le lundi 24 juin 2019 à 10h30
Le lundi 24 juin 2019 à 10h30
Lieu : Palaiseau, Salle Jean Lascoux (Aile 0).
Orateur : Vladimir Kolobov (University of Alabama)
Titre : Electron Kinetics in Low-Temperature Plasmas
Résumé :
Low Temperature Plasmas (LTP) can be broadly defined as plasmas with electron energies of the order of ionization potential of atoms and molecules (about 10 eV). LTPs could be weakly ion- ized and collisional, as in gas discharges, or fully ionized and collisionless, as in space. Colli- sionless plasmas often demonstrate collisional behavior due to wave-particle interactions and turbulence, whereas collisional plasmas exhibit collisionless phenomena such as stochastic elec- tron heating and anomalous skin effect.
The common feature of LTPs is their nonequilibrium nature. In particular, electrons are far from equilibrium with ions and neutrals. They are even not in equilibrium within their own en- semble, and they can be out of equilibrium with electric fields that maintain the plasma. The main causes of electron non-equilibrium are : a) large spatial gradients, b) strong electric fields, c) fast temporal variations, d) collisions with neutral plasma species. Even for a spatially uniform, steady plasma, the dominance of electron collisions with neutrals and, specially, inelastic colli- sions, over Coulomb interactions guarantees non-Maxwellian Electron Distribution Function (EDF). The non- Maxwellian EDFs are also typical for space plasmas. In particular, the for- mation of three groups of electrons (core, strahl and halo) in solar wind has deep similarities with the formation of three electron groups in gas discharges.
In our presentation, we will describe recent advances in the field of electron kinetics in LTP illustrating multi-disciplinary nature of the subject (space and laboratory plasma, collision- less and collisional plasmas, low-pressure and high-pressure discharges) [1]. We will discuss non-local kinetics and non-local electrodynamics in low-pressure rf plasmas, the formation of electron groups in gas discharges and solar wind, and the dynamics of runaway electrons in pulsed breakdown of dielectrics. The development of kinetic solvers with adaptive mesh in phase space and hybrid kinetic-fluid plasma models [2] will be also discussed.
References
[1] V I Kolobov and V A Godyak, Electron kinetics in low-temperature plasma, Invited Perspec- tive Paper, to appear in Phys. Plasma (2019).
[2] V I Kolobov and F Deluzet, Adaptive Kinetic-Fluid Models for Plasma Simulations on Mod- ern Computer Systems, Front. Phys. | doi : 10.3389/fphy.2019.00078
Dr. Vladimir Kolobov is Technical Fellow at CFD Research Corporation and Adjunct Professor at the University of Alabama in Huntsville. He obtained PhD degree in 1989 from St. Petersburg University in Russia, and was a visiting scientist at Universite P. Sabatier, in Toulouse, France, the University of Wisconsin in Madison, and the University of Houston in Texas. After joining CFDRC in 1997, he has been responsible for the development of computational tools for a broad range of applications from material processing to aerospace and nanoscience. Dr. Kolobov was a key architect of commercial software, CFD-ACE+Plasma, for simulations of plasma devices and pro- cesses, and Unified Flow Solver for multi-scale kinetic-fluid simulations. He was a Principal Investi- gator of several successful SBIR/STTR projects funded by NSF, AFRL, NASA, AFOSR, DARPA and Dept. of Commerce, as well as a PI and Manager for numerous industrial projects from GE, Samsung, TEL, Panasonic, MKS Instruments, ABB, Inficon, and other companies. Dr. Kolobov has made distinctive contributions to the advancements of plasma science and its industrial applications. He is IEEE Fellow for contributions to theory, simulation and software development for industrial plasma. Currently, he is a co-Director of $20M NSF EPSCoR project “Connecting Plasma Universe to Plasma Technologies in Alabama.”
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