Strong Anisotropic MHD Turbulence with Cross Helicity

Abstract

This paper proposes a new phenomenology for strong incompressible MHD turbulence with nonzero cross helicity. This phenomenology is then developed into a quantitative Fokker-Planck model that describes the time evolution of the anisotropic power spectra of the fluctuations propagating parallel and anti-parallel to the background magnetic field. It is found that in steady state the power spectra of the magnetic field and total energy are steeper than a Kolmogorov spectrum and become increasingly steep as C/E increases, where C is the cross helicity and E is the fluctuation energy. Increasing C with fixed E increases the time required for energy to cascade to smaller scales, reduces the cascade power, and increases the anisotropy of the small-scale fluctuations. The implications of these results for the solar wind and solar corona are discussed in some detail.

30 pages, 5 figures, accepted for publication in ApJ

References in corpus (5)

• Self-consistent Coronal Heating and Solar Wind Acceleration from Anisotropic Magnetohydrodynamic Turbulence
• Simulations of nonhelical hydromagnetic turbulence
• Kinetic Simulations of Magnetized Turbulence in Astrophysical Plasmas
• Rapid directional alignment of velocity and magnetic field in magnetohydrodynamic turbulence
• Energy spectra stemming from interactions of Alfven waves and turbulent eddies

Cited by in corpus (6)

• Numerical Tests of Fast Reconnection in Weakly Stochastic Magnetic Fields
• Role of cross helicity in magnetohydrodynamic turbulence
• Structure of Stationary Strong Imbalanced Turbulence
• Weakly Turbulent MHD Waves in Compressible Low-Beta Plasmas
• The Turbulent Heating Rate in Strong MHD Turbulence with Nonzero Cross Helicity
• Properties and selected implications of magnetic turbulence for interstellar medium, Local Bubble and solar wind