Kinetic cascade beyond magnetohydrodynamics of solar wind turbulence in two-dimensional hybrid simulations

Abstract

The nature of solar wind turbulence in the dissipation range at scales much smaller than the large MHD scales remains under debate. Here a two-dimensional model based on the hybrid code abbreviated as A.I.K.E.F. is presented, which treats massive ions as particles obeying the kinetic Vlasov equation and massless electrons as a neutralizing fluid. Up to a certain wavenumber in the MHD regime, the numerical system is initialized by assuming a superposition of isotropic Alfvén waves with amplitudes that follow the empirically confirmed spectral law of Kolmogorov. Then turbulence develops and energy cascades into the dispersive spectral range, where also dissipative effects occur. Under typical solar wind conditions, weak turbulence develops as a superposition of normal modes in the kinetic regime. Spectral analysis in the direction parallel to the background magnetic field reveals a cascade of left-handed Alfvén/ion-cyclotron waves up to wave vectors where their resonant absorption sets in, as well as a continuing cascade of right-handed fast-mode and whistler waves. Perpendicular to the background field, a broad turbulent spectrum is found to be built up of fluctuations having a strong compressive component. Ion-Bernstein waves seem to be possible normal modes in this propagation direction for lower driving amplitudes. Also signatures of short-scale pressure-balanced structures (very oblique slow-mode waves) are found.

9 pages, 12 figures, link to publisher version: http://pop.aip.org/resource/1/phpaen/v19/i2/p022305_s1?isAuthorized=yes

References in corpus (5)

• Small Scale Energy Cascade of the Solar Wind Turbulence
• Gyrokinetic turbulence: a nonlinear route to dissipation through phase space
• Inertial range turbulence in kinetic plasmas
• Correlations between the proton temperature anisotropy and transverse high-frequency waves in the solar wind
• Cascade and Damping of Alfvén-Cyclotron Fluctuations: Application to Solar Wind Turbulence Spectrum

Cited by in corpus (10)

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• Fully kinetic versus reduced-kinetic modelling of collisionless plasma turbulence
• The Structure of Plasma Heating in Gyrokinetic Alfvénic Turbulence
• Nonlinear and Linear Timescales near Kinetic Scales in Solar Wind Turbulence
• Extended MHD turbulence and its applications to the solar wind
• Parametric decay of oblique Alfvén waves in two-dimensional hybrid simulations
• Multi-scale Pressure-balanced Structures in Three-dimensional Magnetohydrodynamic Turbulence
• Magnetohydrodynamic Slow Mode with Drifting He${}^{++}$: Implications for Coronal Seismology and the Solar Wind
• Proton and Helium Heating by Cascading Turbulence in a Low-beta Plasma