# Energy transfer, pressure tensor and heating of kinetic plasma

## TL;DR

This paper investigates how energy is transferred and dissipated in kinetic plasma turbulence using fully kinetic simulations and scale-dependent analysis, revealing new insights into collisionless heating mechanisms.

## Contribution

It introduces a novel scale-dependent filtering method to analyze energy transfer in kinetic plasma, highlighting the role of pressure work in collisionless energy dissipation.

## Key findings

- Energy cascade is highly inhomogeneous across scales.
- Pressure work correlates strongly with velocity gradients.
- Identifies a collisionless channel for energy conversion.

## Abstract

Kinetic plasma turbulence cascade spans multiple scales ranging from macroscopic fluid flow to sub-electron scales. Mechanisms that dissipate large scale energy, terminate the inertial range cascade and convert kinetic energy into heat are hotly debated. Here we revisit these puzzles using fully kinetic simulation. By performing scale-dependent spatial filtering on the Vlasov equation, we extract information at prescribed scales and introduce several energy transfer functions. This approach allows highly inhomogeneous energy cascade to be quantified as it proceeds down to kinetic scales. The pressure work, $-\left( \boldsymbol{P} \cdot \nabla \right) \cdot \boldsymbol{u}$, can trigger a channel of the energy conversion between fluid flow and random motions, which is a collision-free generalization of the viscous dissipation in collisional fluid. Both the energy transfer and the pressure work are strongly correlated with velocity gradients.