Spectral evolution of two-dimensional kinetic plasma turbulence in the wavenumber-frequency domain

TL;DR

This paper introduces a new method to analyze plasma turbulence evolution by tracking dispersion relations in the energy spectrum within the wavenumber-frequency domain, demonstrated through hybrid plasma simulations.

Contribution

The paper presents a novel approach for studying plasma turbulence evolution in the ion kinetic regime using dispersion relation tracking in the energy spectrum.

Findings

Identified four key dispersion relations in plasma turbulence.

Showed turbulence cascades along dispersion relations during early decay.

Observed increasing frequency broadening over time.

Abstract

We present a method for studying the evolution of plasma turbulence by tracking dispersion relations in the energy spectrum in the wavenumber-frequency domain. We apply hybrid plasma simulations in a simplified two-dimensional geometry to demonstrate our method and its applicability to plasma turbulence in the ion kinetic regime. We identify four dispersion relations: ion-Bernstein waves, oblique whistler waves, oblique Alfv\'en/ion-cyclotron waves, and a zero-frequency mode. The energy partition and frequency broadening are evaluated for these modes. The method allows us to determine the evolution of decaying plasma turbulence in our restricted geometry and shows that it cascades along the dispersion relations during the early phase with an increasing broadening around the dispersion relations.