Frozen-In Magnetic Field Lines and Alfvén Wave Generation in Weakly Ionized Plasma

Abstract

On the basis of the three-fluid approximation, we consider the generation of linear Alfvén waves with periods ${\gtrsim}\,10^{-3}~\mbox{s}$ in the collisional partially ionized plasma of the solar photosphere. The results obtained in previous work (Tsap, Stepanov, and Kopylova in Solar Phys. 270, 205, 2011) are generalized for the case of the arbitrary ratio between the initial velocities of ions and neutral atoms. We find that the ponderomotive force plays an important role during Alfvén wave excitation and propagation. Furthermore, the energy flux of Alfvén waves does not depend on the degree of the plasma ionization if the magnetic field lines are frozen into the charged particles. These modes can be effectively generated in the weakly ionized plasma of the solar photosphere.