Lagrangian Coherent Structures in magnetized plasmas: Particle transport in a time dependent magnetic configuration

The concept of Lagrangian Coherent Structures (LCS) has been introduced by G. Haller in the context of transport processes in complex fluid flows [1]. LCS are a generalization of the dynamical structures observed in autonomous and periodic systems to temporally aperiodic flows. They separate the flow domain into macro-regions inside which fast mixing phenomena take place. Over the finite time span which characterizes the LCS these macro-regions do not exchange fluid elements and thus act as transport barriers. In two recent articles [2, 3], we have applied this conceptual framework to the study of particle transport in a magnetized plasma by referring to a simplified model that uses magnetic field lines as a proxy for particle trajectories and that allows us to consider explicitly a magnetic configuration evolving in time on timescales comparable to the particle transit time through the configuration. © 45th EPS Conference on Plasma Physics, EPS 2018. All rights reserved.