On the mechanisms of MHD wave damping in the partially ionized solar plasmas
Abstract
There exist many cases when parameters of the solar plasma are so, that it can not be considered as a fully ionized medium. Even a small presence of neutral atoms in plasma sometimes plays a crucial role for dynamical and energetic processes in it. This, first of all, concerns the processes in the solar photosphere and chromosphere and prominences. Different interaction of electrons, ions and neutral atoms with a magnetic field and each other causes the main specifics of the partially ionized plasma MHD, which differs significantly from the fully ionized case. The key point in the modelling of dynamical processes in the partially ionized plasmas consists in inclusion into the MHD equations set of an adequate form of the generalized Ohm's law and corresponding magnetic induction equation, as well as in the appropriate modification of the momentum and energy equations. These ideas are applied for comparative study of damping of MHD waves (Alfvén wave; fast magnetoacoustic and slow/acoustic modes) due to collisional friction and viscosity in the partially ionized plasmas of the low solar atmosphere and prominences. The performed analysis indicates domination of the collisional friction damping mechanisms in the photosphere and low chromosphere as well as in the majority of cases with prominences. Whereas in the upper solar chromosphere collisional and viscous damping of MHD waves are of the same order of magnitude and should be both taken into account in the models. Specific forms of the generalized Ohm's Law and induction equation are presented and discussed that are suitable for regions of the solar atmosphere which are partially ionised.
- Publication:
-
35th COSPAR Scientific Assembly
- Pub Date:
- 2004
- Bibcode:
- 2004cosp...35..975K