Properties of dispersive Alfvén waves: 3. Hydrodynamics (Very Low, Intermediate, and Low Density Plasmas)

Abstract

The behavior of dispersive Alfvén waves (DAWs), including inertial and kinetic Alfvén waves, in astrophysical plasmas of very low, intermediate, and low pressure is investigated in the hydro dynamic approximation. New full solutions are obtained. Our results are analyzed and compared with those from the kinetic approach. It is shown that one general solution for the DAWs in plasmas of very low, intermediate, and low pressure can be obtained in the framework of the hydrodynamic approach, as opposed to the kinetic one. In the very low damping region, the kinetic and hydrodynamic solutions agree very well; but there are parameter regions where the solutions are essentially different. The influ ence of the astrophysical medium parameters on the DAW behavior and properties is analyzed. All main wave characteristics-the dispersion, damping, polarization, density perturbations, and charge density perturbations-are obtained, whose the consideration is very important for the observation and detection of these waves, as well as for a more correct understanding of their behavior and role in various astrophysical processes taking place in the cosmic medium.