The dissipation of solar wind turbulent fluctuations at electron scales

TL;DR

This study uses realistic two-dimensional kinetic simulations to explore how solar wind turbulence dissipates at electron scales, suggesting a power law cascade and potential linear mechanisms for spectral steepening.

Contribution

It provides the first detailed kinetic simulation analysis of turbulent dissipation at electron scales with realistic parameters and ion-electron mass ratio.

Findings

Power law cascade extends to electron Larmor radius scales.

Linear modes may explain spectral steepening at electron scales.

Particle heating is analyzed in the context of turbulence dissipation.

Abstract

We present two-dimensional fully-kinetic Particle-in-Cell simulations of decaying electromagnetic fluctuations. The computational box is such that wavelengths ranging from electron to ion gyroradii are resolved. The parameters used are realistic for the solar wind, and the ion to electron mass ratio is physical. The understanding of the dissipation of turbulent fluctuations at small scales is thought to be a crucial mechanism for solar wind acceleration and coronal heating. The computational results suggest that a power law cascade of magnetic fluctuations could be sustained up to scales of the electron Larmor radius and smaller. We analyse the simulation results in the light of the Vlasov linear theory, and we comment on the particle heating. The dispersion curves of lightly damped modes in this regime suggest that a linear mechanism could be responsible for the observed steepening of power spectra at electron scales, but a straightforward identification of turbulent fluctuations as an ensemble of linear modes is not possible