Fluid energy cascade rate and kinetic damping: new insight from 3D Landau-fluid simulations

TL;DR

This study uses 3D Landau-fluid simulations to connect fluid energy cascade rates with kinetic Landau damping, revealing how energy dissipates across scales in collisionless plasmas.

Contribution

It demonstrates that simplified fluid models can effectively capture kinetic Landau damping effects in turbulence, bridging fluid and kinetic plasma descriptions.

Findings

Cascade rate reflects Landau damping across scales

Fluid models can analyze dissipation in kinetic plasmas

Insights into collisionless plasma turbulence

Abstract

Using an exact law for incompressible Hall magnetohydrodynamics (HMHD) turbulence, the energy cascade rate is computed from three-dimensional HMHD-CGL (bi-adiabatic ions and isothermal electrons) and Landau fluid (LF) numerical simulations that feature different intensities of Landau damping over a broad range of wavenumbers, typically $0.05\lesssim k_\perp d_i \lesssim100$. Using three sets of cross-scale simulations where turbulence is initiated at large, medium and small scales, the ability of the fluid energy cascade to "sense" the kinetic Landau damping at different scales is tested. The cascade rate estimated from the exact law and the dissipation calculated directly from the simulation are shown to reflect the role of Landau damping in dissipating energy at all scales, with an emphasis on the kinetic ones. This result provides new prospects on using exact laws for simplified fluid models to analyze dissipation in kinetic simulations and spacecraft observations, and new insights into theoretical description of collisionless magnetized plasmas.