Nature of Kinetic Scale Turbulence in the Earth's Magnetosheath

Abstract

We present a combined observational and theoretical analysis to investigate the nature of plasma turbulence at kinetic scales in the Earth's magnetosheath. In the first decade of the kinetic range, just below the ion gyroscale, the turbulence was found to be similar to that in the upstream solar wind: predominantly anisotropic, low-frequency and kinetic Alfvén in nature. A key difference, however, is that the magnetosheath ions are typically much hotter than the electrons, $T_{\mathrm{i}}\gg T_{\mathrm{e}}$, which, together with ${\beta }_{\mathrm{i}}\sim 1$, leads to a change in behaviour in the second decade, close to electron scales. The turbulence here is characterised by an increased magnetic compressibility, following a mode we term the inertial kinetic Alfvén wave, and a steeper spectrum of magnetic fluctuations, consistent with the prediction $E_B(k_{\perp })\propto k_{\perp }^{-11/3}$ that we obtain from a set of nonlinear equations. This regime of plasma turbulence may also be relevant for other astrophysical environments with $T_{\mathrm{i}}\gg T_{\mathrm{e}}$, such as the solar corona, hot accretion flows, and regions downstream of collisionless shocks.

References in corpus (9)

• Recent progress in astrophysical plasma turbulence from solar wind observations
• Multiscale nature of the dissipation range in gyrokinetic simulations of Alfvénic turbulence
• Density Fluctuation Spectrum of Solar Wind Turbulence between Ion and Electron Scales
• Validity of the Taylor Hypothesis for Linear Kinetic Waves in the Weakly Collisional Solar Wind
• Kinetic cascade beyond magnetohydrodynamics of solar wind turbulence in two-dimensional hybrid simulations
• On the electron-ion temperature ratio established by collisionless shocks
• The Violation of the Taylor Hypothesis in Measurements of Solar Wind Turbulence
• Solar wind turbulence from MHD to sub-ion scales: high-resolution hybrid simulations
• Two-fluid turbulence including electron inertia

Cited by in corpus (15)

• The Evolution and Role of Solar Wind Turbulence in the Inner Heliosphere
• Evidence for Electron Landau Damping in Space Plasma Turbulence
• Collisionless Reconnection in Magnetohydrodynamic and Kinetic Turbulence
• Kinetic cascade in solar-wind turbulence: 3D3V hybrid-kinetic simulations with electron inertia
• Energy cascade rate measured in a collisionless space plasma with MMS data and compressible Hall magnetohydrodynamic turbulence theory
• Kinetic plasma turbulence: recent insights and open questions from 3D3V simulations
• Imbalanced kinetic Alfvén wave turbulence: from weak turbulence theory to nonlinear diffusion models for the strong regime
• Variability Of The Magnetic Field Power Spectrum In The Solar Wind At Electron Scales
• Anisotropies of the magnetic field fluctuations at kinetic scales in the solar wind : Cluster observations
• Observational quantification of three-dimensional anisotropies and scalings of space plasma turbulence at kinetic scales
• Space-filter techniques for quasi-neutral hybrid-kinetic models
• Kinetic Scale Spectral Features of Cross Helicity and Residual Energy in the Inner Heliosphere
• Modeling imbalanced collisionless Alfvén wave turbulence with nonlinear diffusion equations
• A Hamiltonian gyrofluid model based on a quasi-static closure
• Magnetic field turbulence in the solar wind at sub-ion scales: in situ observations and numerical simulations