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Nature of kinetic scale turbulence in the Earth's magnetosheath

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Title: Nature of kinetic scale turbulence in the Earth's magnetosheath
Authors: Chen, CHK
Boldyrev, S
Item Type: Journal Article
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, ${T}_{{\rm{i}}}\gg {T}_{{\rm{e}}}$, which, together with ${\beta }_{{\rm{i}}}\sim 1$, leads to a change in behavior in the second decade, close to electron scales. The turbulence here is characterized 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 ${T}_{{\rm{i}}}\gg {T}_{{\rm{e}}}$, such as the solar corona, hot accretion flows, and regions downstream of collisionless shocks.
Issue Date: 22-Jun-2017
Date of Acceptance: 22-May-2017
URI: http://hdl.handle.net/10044/1/48656
DOI: https://dx.doi.org/10.3847/1538-4357/aa74e0
ISSN: 0004-637X
Publisher: American Astronomical Society
Journal / Book Title: Astrophysical Journal
Volume: 842
Issue: 2
Copyright Statement: © 2017. The American Astronomical Society. All rights reserved. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence . Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI (https://creativecommons.org/licenses/by/3.0/)
Sponsor/Funder: Science and Technology Facilities Council (STFC)
Funder's Grant Number: ST/N003748/1
Keywords: Science & Technology
Physical Sciences
Astronomy & Astrophysics
magnetic fields
plasmas
solar wind
turbulence
waves
SOLAR-WIND TURBULENCE
ELECTRON MAGNETOHYDRODYNAMIC TURBULENCE
MAGNETIC-FIELD FLUCTUATIONS
CLUSTER OBSERVATIONS
ASTROPHYSICAL GYROKINETICS
ANISOTROPY MEASUREMENTS
COLLISIONLESS SHOCKS
ALFVENIC TURBULENCE
TAYLOR HYPOTHESIS
DISSIPATION RANGE
0201 Astronomical And Space Sciences
0305 Organic Chemistry
0306 Physical Chemistry (Incl. Structural)
Publication Status: Published
Article Number: 122
Appears in Collections:Space and Atmospheric Physics
Physics



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