Driven two-fluid Alfvén waves in a solar magnetic flux tube with a realistic ionization rate

Context. This study was performed in the context of the chromosphere and low corona heating. Aims. We considered the evolution of driven Alfvén waves in the solar atmosphere, whose initial state was modeled with a realistic ionization profile. We discuss their potential role in plasma heating. Methods. Two- and half-dimensional (2.5 D) numerical simulations of the solar atmosphere were performed with the use of the code JOANNA. The dynamics of the atmosphere was described by the two-fluid equations (and ionization and recombination terms were taken into account) for ions (protons) combined with electrons and neutrals (hydrogen atoms). The initial atmosphere was described by a hydrostatic background supplemented by the Saha equation and embedded in a magnetic flux tube. This background was perturbed by a monochromatic driver that operated in the transversal components of the ion and neutral velocities. Results. We demonstrated that as a result of ion-neutral collisions, Alfvén waves are damped. The damping length grows with the wave period. This is anticipated based on the linear theory for a homogeneous medium. The developed flux-tube model results at higher temperatures rise for shorter periods of the driving wave, and the effect is stronger than for the pure hydrostatic state. Conclusions. We highlight the importance of taking the realistic background plasma into account in the evolution of two-fluid Alfvén waves that participate in the thermal energy release and in the heating in the solar chromosphere and low corona.