Anisotropic turbulence of kinetic Alfvén waves and heating in solar corona

Abstract

Abstract Understanding solar coronal heating has been one of the unresolved problems in solar physics in spite of the many theories that have been developed to explain it. Past observational studies suggested that kinetic Alfvén waves (KAWs) may be responsible for solar coronal heating by accelerating the charged particles in solar plasma. In this paper, we investigated the transient dynamics of KAWs with modified background density due to ponderomotive force and Joule heating. A numerical simulation based on pseudo-spectral method was applied to study the evolution of KAW magnetic coherent structures and generation of magnetic turbulence. Using different initial conditions in simulations, the dependence of KAW dynamics on the nature of inhomogeneous solar plasma was thoroughly investigated. The saturated magnetic power spectra follow Kolmogorov scaling of k −5/3 in the inertial range, then followed by steep anisotropic scaling in the dissipation range. The KAW has anisotropy of k ∥ ∝ k ⊥ 0.53 , k ∥ ∝ k ⊥ 0.50 , k ∥ ∝ k ⊥ 0.83 and k ∥ ∝ k ⊥ 0.30 depending on the kind of initial conditions of inhomogeneity. The power spectra of magnetic field fluctuations showing the spectral anisotropy in wavenumber space indicate that the nonlinear interactions may be redistributing the energy anisotropically among higher modes of the wavenumber. Therefore, anisotropic turbulence can be considered as one of the candidates responsible for the particle energization and heating of the solar plasmas.