Spectrum of Kinetic Alfven Turbulence

TL;DR

This paper proposes a model for strong kinetic Alfvén turbulence at sub-ion scales, predicting specific spectral behaviors that align with numerical simulations and solar wind observations.

Contribution

It introduces a new model for kinetic Alfvén turbulence focusing on two-dimensional structures and their spectral properties at small scales.

Findings

Spectral energy spectrum follows $k_ot^{-8/3}$ scaling.

Model agrees with numerical simulations.

Explains observed fluctuations in solar wind at sub-proton scales.

Abstract

A model for strong kinetic Alfv\'en plasma turbulence at scales smaller than the ion gyroscale is proposed. It is argued that magnetic and density fluctuations are concentrated mostly at two-dimensional structures, which leads to their Fourier energy spectra $E(k_\perp)\propto k_{\perp}^{-8/3}$, where $k_\perp$ is the wave-vector component normal to the strong background magnetic field. The results are shown to be in good agreement with numerical simulations, and they can explain recent observations of magnetic and density fluctuations in the solar wind at sub-proton scales.