Analytical treatment of particle motion in circularly polarized slab-mode wave fields

: Schreiner C, Vainio R, Spanier F

Publisher: CAMBRIDGE UNIV PRESS

: Cambridge

: 2018

: Journal of Plasma Physics

: JOURNAL OF PLASMA PHYSICS

: J PLASMA PHYS

: ARTN 905840104

: 84

: 1

: 26

: 0022-3778

: 1469-7807

DOI: https://doi.org/10.1017/S0022377817001015

Wave-particle interaction is a key process in particle diffusion in collisionless plasmas. We look into the interaction of single plasma waves with individual particles and discuss under which circumstances this is a chaotic process, leading to diffusion. We derive the equations of motion for a particle in the fields of a magnetostatic, circularly polarized, monochromatic wave and show that no chaotic particle motion can arise under such circumstances. A novel and exact analytic solution for the equations is presented. Additional plasma waves lead to a breakdown of the analytic solution and chaotic particle trajectories become possible. We demonstrate this effect by considering a linearly polarized, monochromatic wave, which can be seen as the superposition of two circularly polarized waves. Test particle simulations are provided to illustrate and expand our analytical considerations.