@article{Hellinger:2015:2/L32,
author = {Hellinger, P and Matteini, L and Landi, S and Verdini, A and Franci, L and Trávnícek, PM},
doi = {2/L32},
journal = {Astrophysical Journal Letters},
title = {Plasma turbulence and kinetic instabilities at ion scales in the expanding solar wind},
url = {http://dx.doi.org/10.1088/2041-8205/811/2/L32},
volume = {811},
year = {2015}
}

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TY  - JOUR
AB  - The relationship between a decaying strong turbulence and kinetic instabilities in a slowly expanding plasma isinvestigated using two-dimensional (2D) hybrid expanding box simulations. We impose an initial ambientmagnetic field perpendicular to the simulation box, and we start with a spectrum of large-scale, linearly polarized,random-phase Alfvénic fluctuations that have energy equipartition between kinetic and magnetic fluctuations andvanishing correlation between the two fields. A turbulent cascade rapidly develops; magnetic field fluctuationsexhibit a power-law spectrum at large scales and a steeper spectrum at ion scales. The turbulent cascade leads to anoverall anisotropic proton heating, protons are heated in the perpendicular direction, and, initially, also in theparallel direction. The imposed expansion leads to generation of a large parallel proton temperature anisotropywhich is at later stages partly reduced by turbulence. The turbulent heating is not sufficient to overcome theexpansion-driven perpendicular cooling and the system eventually drives the oblique firehose instability in a formof localized nonlinear wave packets which efficiently reduce the parallel temperature anisotropy. This workdemonstrates that kinetic instabilities may coexist with strong plasma turbulence even in a constrained 2D regime.
AU  - Hellinger,P
AU  - Matteini,L
AU  - Landi,S
AU  - Verdini,A
AU  - Franci,L
AU  - Trávnícek,PM
DO  - 2/L32
PY  - 2015///
SN  - 2041-8213
TI  - Plasma turbulence and kinetic instabilities at ion scales in the expanding solar wind
T2  - Astrophysical Journal Letters
UR  - http://dx.doi.org/10.1088/2041-8205/811/2/L32
UR  - http://hdl.handle.net/10044/1/44563
VL  - 811
ER  - 

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