A parametric study of entropy and energy conversion during collisionless Landau damping of plasma waves

Earth's magnetosheath is an excellent natural laboratory for the study of physical processes occurring in turbulence in weakly collisional plasmas. Landau damping has been directly identified via in situ satellite measurements as an energy conversion process there (Chen et al., Nature Comm., 10, 740, 2019) using the field-particle correlation technique (Klein and Howes, ApJL, 826, L30, 2016). In a new approach to studying energy conversion (Cassak et al., PRL, 130, 085201, 2023), a first-principles, non-perturbative entropy-based approach was developed to quantify energy conversion from all moments of the phase space density. Here, we perform a parametric study of energy conversion in one-dimensional (1D) Landau damping of a plasma wave employing 1D-1V particle-in-cell (PIC) simulations using kinetic entropy and the field-particle correlation technique as diagnostics. We analyze the interchange of position- and velocity-space entropy and compare the rates of energy conversion from the field-particle correlation to the energy conversion rates associated with higher order moments of the phase space density to get insights into how energy is converted between the plasma and the electric field.