Extended MHD turbulence and its applications to the solar wind

Abstract

Extended MHD is a one-fluid model that incorporates two-fluid effects such as electron inertia and the Hall drift. This model is used to construct fully nonlinear Alfvénic wave solutions, and thereby derive the kinetic and magnetic spectra by resorting to a Kolmogorov-like hypothesis based on the constant cascading rates of the energy and generalized helicities of this model. The magnetic and kinetic spectra are derived in the ideal $\left(k<1/{\lambda }_i\right)$, Hall $\left(1/{\lambda }_i<k<1/{\lambda }_e\right)$, and electron inertia $\left(k>1/{\lambda }_e\right)$ regimes; $k$ is the wavenumber and ${\lambda }_s=c/{\omega }_{ps}$ is the skin depth of species `$s$'. In the Hall regime, it is shown that the emergent results are fully consistent with previous numerical and analytical studies, especially in the context of the solar wind. The focus is primarily on the electron inertia regime, where magnetic energy spectra with power-law indexes of $-11/3$ and $-13/3$ are always recovered. The latter, in particular, is quite close to recent observational evidence from the solar wind with a potential slope of approximately $-4$ in this regime. It is thus plausible that these spectra may constitute a part of the (extended) inertial range, as opposed to the standard `dissipation' range paradigm.

15 pages; 4 figures; accepted for publication in ApJ (2016)

References in corpus (13)

• Small Scale Energy Cascade of the Solar Wind Turbulence
• Magnetic fields in protoplanetary disks
• Solar wind turbulent spectrum at plasma kinetic scales
• Wave turbulence in incompressible Hall MHD
• Multi-scale Hall-MHD turbulence in the solar wind
• Multiscale nature of the dissipation range in gyrokinetic simulations of Alfvénic turbulence
• Kinetic cascade beyond magnetohydrodynamics of solar wind turbulence in two-dimensional hybrid simulations
• Hamiltonian Formalism of Extended Magnetohydrodynamics
• The dissipation of solar wind turbulent fluctuations at electron scales
• Action Principles for Extended MHD Models
• Modeling astrophysical outflows via the unified Dynamo-Reverse Dynamo mechanism
• Spectral breaks of Alfvenic turbulence in a collisionless plasma
• Two-fluid turbulence including electron inertia

Cited by in corpus (5)

• Imbalanced kinetic Alfvén wave turbulence: from weak turbulence theory to nonlinear diffusion models for the strong regime
• Exact scaling laws for helical three-dimensional two-fluid turbulent plasmas
• On the structure and statistical theory of turbulence of extended magnetohydrodynamics
• Structure and computation of two-dimensional incompressible extended MHD
• Yet Another Modification of Relativistic Magnetohydrodynamic Waves: Electron Thermal Inertia