A Universal Law for Solar-Wind Turbulence at Electron Scales

Abstract

The interplanetary magnetic fluctuation spectrum obeys a Kolmogorovian power law at scales above the proton inertial length and gyroradius which is well regarded as an inertial range. Below these scales a power law index around $-2.5$ is often measured and associated to nonlinear dispersive processes. Recent observations reveal a third region at scales below the electron inertial length. This region is characterized by a steeper spectrum that some refer to it as the dissipation range. We investigate this range of scales in the electron magnetohydrodynamic approximation and derive an exact and universal law for a third-order structure function. This law can predict a magnetic fluctuation spectrum with an index of $-11/3$ which is in agreement with the observed spectrum at the smallest scales. We conclude on the possible existence of a third turbulence regime in the solar wind instead of a dissipation range as recently postulated.

11 pages, will appear in Astrophys. J

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• Nature of Kinetic Scale Turbulence in the Earth's Magnetosheath
• New insight into short wavelength solar wind fluctuations from Vlasov theory
• A Kolmogorov-Like Exact Relation for Compressible Polytropic Turbulence
• Kinetic-scale magnetic turbulence and finite Larmor radius effects at Mercury
• The Ion Transition Range of Solar Wind Turbulence in the Inner Heliosphere: Parker Solar Probe Observations
• An alternative formulation for exact scaling relations in hydrodynamic and magnetohydrodynamic turbulence
• Chiral Exact Relations for Helicities in Hall Magnetohydrodynamic Turbulence
• Extended MHD turbulence and its applications to the solar wind
• Compressible turbulence in the interstellar medium: New insights from a high-resolution supersonic turbulence simulation
• von Kármán-Howarth equation for three-dimensional two-fluid plasmas
• Turbulence in Magnetized Pair Plasmas
• Exact scaling laws for helical three-dimensional two-fluid turbulent plasmas
• Entanglement of helicity and energy in kinetic Alfven wave/whistler turbulence
• Scale-to-scale energy transfer rate in compressible two-fluid plasma turbulence
• -8/3 spectrum in kinetic Alfvén wave turbulence: implications for the solar wind
• Direction of cascades in a magnetofluid model with electron skin depth and ion sound Larmor radius scales
• Wave Turbulence in Inertial Electron Magnetohydrodynamics
• Influence of ion-to-electron temperature ratio on tearing instability and resulting subion-scale turbulence in a low-${\beta }_e$ collisionless plasma
• The effects of finite electron inertia on helicity-barrier-mediated turbulence
• Gyrofluid simulations of turbulence and reconnection in space plasmas