JET-PLUME: Judging Energy Transfer in Magnetized Plasmas and Identifying Cross-Field Energization

We present JET-PLUME (Judging Energy Transfer in a Plasma in a Uniform Magnetized Environment), an open-source extension of PLUME (Klein et al., 2025), a numerical Vlasov–Maxwell dispersion solver for N parallel drifting bi-Maxwellians. This code analytically computes net phase-space energy transfer using the Field–Particle Correlation (FPC) diagnostic for wave–particle interactions governed by hot linear plasma theory in addition to the perturbed distribution function for each species. Our results demonstrate the importance of cross-field energization, i.e. contributions associated with the off-diagonal elements of the susceptibility tensor, which can drive fluctuations in $f_{s,1}$ comparable in magnitude to those produced by the traditionally emphasized diagonal terms. In a system with such properties, we isolate the diagonal and off-diagonal contributions predicted by linear theory and compare them to the phase-space signature of Landau damping from a kinetic Alfvén wave. Finite Larmor radius effects in this system generate wave growth that is significant but weaker than the damping associated with parallel resonances near the wave's phase velocity, resulting in overall damping of the wave. These effects are critical to interpreting in-situ measurements of phase-space energy transfer in the kinetic regime, especially because spacecraft naturally produce detailed measurements of particle velocity distributions but are fundamentally constrained to a single space-time trajectory, limiting their ability to resolve spatial and temporal structures.