Authors: Hasith Perera (West Virginia University),Paul Cassak (West Virginia University),Hasan Barbhuiya (West Virginia University),Greg Howes (University of Iowa)

A forefront area of research in weakly collisional or collisionless plasmas is how energy is converted between different forms, especially the conversion of energy between electromagnetic fields and the plasma, and how that energy is ultimately converted to internal energy. The field-particle correlation (Klein and Howes, 2016) is one such diagnostic based on a single-point measurement of the electromagnetic field and the velocity distribution function to look at the velocity-space signature during energy transfer. In a newly developed approach (Cassak et al., 2023), a first-principles, non-perturbative entropy-based approach was derived, that quantifies energy conversion from all moments of the phase space density which is being used to study energy conversion in reconnection, turbulence, and shocks. In this study, we treat energy conversion in one-dimensional (1D) Landau damping of a plasma wave, a well-documented process by which energy is exchanged between particles and the electric field. The lower dimensionality of the system allows for an in-depth and well-controlled study. We use a 1D-1V particle-in-cell (PIC) simulation to study energy conversion during Landau damping 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 and the higher order moments of the distribution function to get insights into how energy is converted between the plasma and the electric field during Landau damping of plasma waves.