Alfvén-like mode in partially ionized solar atmosphere

Abstract

The partially ionized part of the solar atmosphere is investigated within the framework of a single-fluid magnetohydrodynamic (MHD) description including the non-ideal effects such as the Hall effect and the ambipolar diffusion in the generalized Ohm’s Law. In this paper, we study the propagation and damping of an Alfvén-like mode in the partially ionized solar atmosphere. It is found that the Hall effect, in addition to introducing strong dispersion, breaks the symmetry between the co- and the counter-propagating wave modes at the length scale approaching the Hall length-scale. The Hall effect creates short wavelength mode with circular polarization. The damping of Alfvén- like mode, in a partially ionized solar atmosphere, is found to be caused mainly by the Coulomb and the Cowling diffusivity. A comparison of the Hall (ηH), the Cowling (ηA) and the Coulomb (η) diffusivities shows that the ambipolar effect is dominant beyond the height of 175 km above the solar surface, for the solar model given by Cox (2000) [Cox, A.N., 2000. Allen’s Astrophysical Quantities, fourth ed. Springer, New York] and chosen magnetic field.