Scaling of the electron dissipation range of solar wind turbulence

TL;DR

This study analyzes 10 years of Cluster spacecraft data to investigate the magnetic energy spectra at electron scales in solar wind turbulence, revealing spectral breakpoints near the electron gyroscale and discussing implications for energy dissipation mechanisms.

Contribution

It provides a comprehensive statistical analysis of electron-scale turbulence spectra in the solar wind, highlighting spectral breakpoints and discussing the nature of plasma modes involved.

Findings

Spectral breakpoints are often near the electron gyroscale.

Spectra steepen beyond the breakpoints, indicating dissipation.

Instrumental limitations hinder precise scaling determination below electron scales.

Abstract

Electron scale solar wind turbulence has attracted great interest in recent years. Clear evidences have been given from the Cluster data that turbulence is not fully dissipated near the proton scale but continues cascading down to the electron scales. However, the scaling of the energy spectra as well as the nature of the plasma modes involved at those small scales are still not fully determined. Here we survey 10 years of the Cluster search-coil magnetometer (SCM) waveforms measured in the solar wind and perform a statistical study of the magnetic energy spectra in the frequency range [$1, 180$]Hz. We show that a large fraction of the spectra exhibit clear breakpoints near the electon gyroscale $\rho_e$, followed by steeper power-law like spectra. We show that the scaling below the electron breakpoint cannot be determined unambiguously due to instrumental limitations that will be discussed in detail. We compare our results to recent ones reported in other studies and discuss their implication on the physical mechanisms and the theoretical modeling of energy dissipation in the SW.