Solar wind turbulence from MHD to sub-ion scales: high-resolution hybrid simulations

Abstract

We present results from a high-resolution and large-scale hybrid (fluid electrons and particle-in-cell protons) two-dimensional numerical simulation of decaying turbulence. Two distinct spectral regions (separated by a smooth break at proton scales) develop with clear power-law scaling, each one occupying about a decade in wave numbers. The simulation results exhibit simultaneously several properties of the observed solar wind fluctuations: spectral indices of the magnetic, kinetic, and residual energy spectra in the magneto-hydrodynamic (MHD) inertial range along with a flattening of the electric field spectrum, an increase in magnetic compressibility, and a strong coupling of the cascade with the density and the parallel component of the magnetic fluctuations at sub-proton scales. Our findings support the interpretation that in the solar wind large-scale MHD fluctuations naturally evolve beyond proton scales into a turbulent regime that is governed by the generalized Ohm's law.

5 pages, 5 figures; introduction and conclusions changed, references updated, accepted for publication in ApJL

References in corpus (11)

• Observation of inertial energy cascade in interplanetary space plasma
• Small Scale Energy Cascade of the Solar Wind Turbulence
• Solar wind turbulent spectrum at plasma kinetic scales
• Radial Dependence of the Frequency Break Between Fluid and Kinetic Scales in the Solar Wind Fluctuations
• Density Fluctuation Spectrum of Solar Wind Turbulence between Ion and Electron Scales
• Comparison of spectral slopes of magnetohydrodynamic and hydrodynamic turbulence and measurements of alignment effects
• Numerical Measurements of the Spectrum in Magnetohydrodynamic Turbulence
• Evolution of turbulence in the expanding solar wind, a numerical study
• The dissipation of solar wind turbulent fluctuations at electron scales
• Solar Wind Electric Fields in the Ion Cyclotron Frequency Range
• Parallel Electric Field Spectrum of Solar Wind Turbulence

Cited by in corpus (14)

• Nature of Kinetic Scale Turbulence in the Earth's Magnetosheath
• Magnetic reconnection as a driver for a sub-ion scale cascade in plasma turbulence
• Plasma beta dependence of the ion-scale spectral break of solar wind turbulence: high-resolution 2D hybrid simulations
• Critical Balance and the Physics of MHD Turbulence
• Exploring the Statistics of Magnetic Reconnection X-points in Kinetic Particle-in-Cell (PIC) Turbulence
• Energy conversion in turbulent weakly-collisional plasmas: Eulerian Hybrid Vlasov-Maxwell simulations
• Anisotropies of the magnetic field fluctuations at kinetic scales in the solar wind : Cluster observations
• Linking Fluid and Kinetic Scales in Solar Wind Turbulence
• Spacetime Hall-MHD turbulence at sub-ion scales: structures or waves?
• Conditions for proton temperature anisotropy to drive instabilities in the solar wind
• Three-dimensional local anisotropy of velocity fluctuations in the solar wind
• Exact hybrid-kinetic equilibria for magnetized plasmas with shearing flows
• Current sheets, plasmoids and flux ropes in the heliosphere. Part II: Theoretical aspects
• Anisotropic electron heating in turbulence-driven magnetic reconnection in the near-Sun solar wind