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Home > Seminars & Defenses > Past seminars, PhD & HDR defenses > 2019 > Séminaires 2019 > Le jeudi 4 avril 2019 à 10h30

Le jeudi 4 avril 2019 à 10h30

Lieu : Palaiseau salle Jean Lascoux (CPHT, aile 0).

10h30 - Accueil café

11h00 - Séminaire

Orateur :Maxime Lesur (Maître-de-Conférences, Institut Jean Lamour - Nancy, Université de Lorraine)

Titre : Collisionless transport driven by nonlinear kinetic effects

Résumé :
Understanding plasma turbulence, and associated transport of mean fields, is key in fusion science, astrophysics, space weather, and space exploration. In hot plasmas, collisions are so rare that fine scale structures develop in the phase-space of the particle distribution: coupling both real space and velocity (or energy) space. These structures are driven by nonlinear wave-particle interactions, which is an essentially kinetic process.
A paradigmatic example of such fine-scale structures is a vortex-like structure, which is formed by the self-consistent, self-sustained trapping of particles within potential wells localized in phase-space (“electrostatic trapping”). Even in regimes where these phase-space vortices are microscopic, they can yield macroscopic impacts, on fluctuation statistics, large-scale structure formation, transport, and even triggering new instabilities (subcritical instabilities) and a new kind of turbulence (phase-space turbulence).
In this seminar, I will provide a tutorial on electrostatic trapping, and review recent investigations of the formation, the dynamics, and the macroscopic impacts of phase-space vortices and phase-space turbulence, mainly based on first-principle kinetic numerical simulations of relatively reduced models. I will cover various plasma configurations, in 1D and 3D, with and without energetic particles, and with or without mean field inhomogeneity, corresponding to various contexts of magnetic fusion plasmas, space plasmas, and laser/plasma interactions.

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