Three-dimensional Simulations and Spacecraft Observations of Sub-ion Scale Turbulence in the Solar Wind: Influence of Landau Damping

Three-dimensional nonlinear finite Larmor radius (FLR)-Landau fluid simulations, which include some small-scale kinetic effects, are performed to explore the nature of the sub-ion scale turbulence in the solar wind and to investigate the role of Landau damping and FLR corrections. The resulting stea...

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Bibliographic Details
Published in:The Astrophysical journal 2017-04, Vol.839 (2), p.122
Main Authors: Kobayashi, S., Sahraoui, F., Passot, T., Laveder, D., Sulem, P. L., Huang, S. Y., Henri, P., Smets, R.
Format: Article
Language:English
Subjects:
ACCELERATION
acceleration of particles
Alfven waves
Astrophysics
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COMPARATIVE EVALUATIONS
COMPRESSIBILITY
COMPUTERIZED SIMULATION
CORRECTIONS
DISPERSION RELATIONS
FLUCTUATIONS
Fluid dynamics
Fluid flow
IONS
LANDAU DAMPING
LARMOR RADIUS
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
magnetohydrodynamics (MHD)
NONLINEAR PROBLEMS
Physics
PLASMA
plasmas
Sciences of the Universe
Simulation
Slopes
SOLAR WIND
Solar wind turbulence
Space Physics
SPACE VEHICLES
Spacecraft
SPECTRA
STEADY-STATE CONDITIONS
THREE-DIMENSIONAL CALCULATIONS
TURBULENCE
Turbulent fluctuations
Wavelengths
Wind measurement
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Description
Summary:Three-dimensional nonlinear finite Larmor radius (FLR)-Landau fluid simulations, which include some small-scale kinetic effects, are performed to explore the nature of the sub-ion scale turbulence in the solar wind and to investigate the role of Landau damping and FLR corrections. The resulting steady-state magnetic power spectrum in the dispersive range display exponents that vary within a range of values compatible with statistical results reported from in situ spacecraft measurements of solar wind turbulence as well as from gyrokinetic simulations. The spectral slopes are shown to depend on the strength of the nonlinear effects and on the scale at which turbulent fluctuations are driven in the simulations. The influence of Landau damping is addressed by comparison with simulations where the double-adiabatic closure is imposed. The role of FLR corrections is also analyzed. Comparison with in situ observations in the solar wind are performed to enlighten the influence of the fluctuations power at different scales on the spectral slopes in the sub-ion range. Using diagnosis of both magnetic compressibility and frequency-wavenumber spectra, it is shown that in spite of the evidence of the presence of fast-magnetosonic modes, the magnetic energy is mostly distributed around the kinetic Alfvén waves and the slow modes, in agreement with solar wind measurements. The observed large broadening about the linear dispersion relations may reflect the presence of coherent structures.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aa67f2