The wave propagation in the partially ionized ionosphere plays an important role in the magnetosphere-ionosphere coupling. For example, the ionosphere may supports very low-frequency Alfvénwave, which can be caused by a balance between the bulk fluid inertia (mostly due to neutrals in the lower and middle E-region) and the deformation of the magnetic field. The plasma-neutral collisional momentum exchange facilitates the transfer of the magnetic stress (felt directly by the ions) to the neutrals. Therefore, in the low-frequency limit (with respect to the neutral-ion collision frequency), waves through the ionosphere can propagate with very little damping. In the vanishing plasma inertia limit, waves can be excited due to the loading of neutral inertia on the field lines and thus may have very long wavelength and can easily couple to the magnetosphere. The frequency of these waves is below few Hz. In the present work, the dynamics of neutral particles have been included in the single-fluid, ideal magnetohydro- dynamic like framework, where owing to the frequent collisions between the neutral and plasma particles the magnetic field is no longer frozen in the partially ionized fluid but slips through it. The relative importance of this non-ideal behavior of the fluid is dependent on how often the plasma particles suffer collision with the neutral particles. In the limiting case, when the non-ideal effects can be ignored, the equations for both the partially and fully ionized plasmas are identical except inertia of the partially ionized fluid is carried by both the ions and the neutrals.
|Number of pages||11|
|Journal||African Review of Physics|
|Publication status||Published - 2016|