Wave-particle interaction in contact with a chaotic thermostat

This numerical investigation explores the properties of the wave-particle interaction in a situation in which the particle is simultaneously in contact with a chaotic thermostat [G. J. Morales, Phys. Rev. E 99, 062218 (2019)]. The role of the thermostat is to establish a Maxwellian velocity distribution function through deterministic chaotic orbits. The particle response is quantified by calculating the complex mobility, mu k , omega , from the numerically obtained orbits for a wave of constant amplitude, with wave number k and frequency omega. It is found that in the limit of weak coupling to the thermostat, the behavior is that predicted by the plasma dispersion function, which implies collisionless Landau damping. As the coupling to the thermostat is increased (equivalent to increasing collisionality), the behavior follows the generalized collisional plasma dispersion function [Fried et al., Phys. Fluids 9, 292 (1966)]. For strong coupling, the response agrees with the Braginskii mobility. The nonlinear mobility associated with intermittent particle trapping is obtained for the various collisional regimes.