Phase mixing importance for both Landau instability and damping

Physique Mathématique

Salle Kampé de Fériet M2
Yves Elskens
Laboratoire de Physique des Interactions Ioniques et Moléculaires, Aix-Marseille Université
Mardi, 20 Février, 2018 - 11:00 - 12:00

We discuss the self-consistent dynamics of plasmas by means of hamiltonian formalism for a system of N near-resonant electrons interacting with a single Langmuir wave. The connection with the Vlasov description is revisited through the numerical calculation of the van Kampen-like eigenfrequencies of the linearized dynamics for many degrees of freedom. Both the exponential-like growth as well as damping of the Langmuir wave are shown to emerge from a phase mixing effect among beam modes, revealing unexpected similarities between the stable and unstable regimes.