Numerical simulations of the lower solar atmosphere heating by two-fluid nonlinear Alfvén waves

Abstract

<jats:p><jats:italic>Context.</jats:italic> We present new insight into the long-standing problem of plasma heating in the lower solar atmosphere in terms of collisional dissipation caused by two-fluid Alfvén waves.</jats:p> <jats:p><jats:italic>Aims.</jats:italic> Using numerical simulations, we study Alfvén wave propagation and dissipation in a magnetic flux tube and their heating effect.</jats:p> <jats:p><jats:italic>Methods.</jats:italic> We set up 2.5-dimensional numerical simulations with a semi-empirical model of a stratified solar atmosphere and a force-free magnetic field mimicking a magnetic flux tube. We consider a partially ionized plasma consisting of ion + electron and neutral fluids, which are coupled by ion-neutral collisions.</jats:p> <jats:p><jats:italic>Results.</jats:italic> We find that Alfvén waves, which are directly generated by a monochromatic driver at the bottom of the photosphere, experience strong damping. Low-amplitude waves do not thermalize sufficient wave energy to heat the solar atmospheric plasma. However, Alfvén waves with amplitudes greater than 0.1 km s<jats:sup>−1</jats:sup> drive through ponderomotive force magneto-acoustic waves in higher atmospheric layers. These waves are damped by ion-neutral collisions, and the thermal energy released in this process leads to heating of the upper photosphere and the chromosphere.</jats:p> <jats:p><jats:italic>Conclusions.</jats:italic> We infer that, as a result of ion-neutral collisions, the energy carried initially by Alfvén waves is thermalized in the upper photosphere and the chromosphere, and the corresponding heating rate is large enough to compensate radiative and thermal-conduction energy losses therein.</jats:p>

3D numerical simulations of propagating two-fluid, torsional Alfvén waves and heating of a partially ionized solar chromosphere

“…4 plasma temperature, mainly in the upper chromosphere just below the transition region. Note that the relative plasma temperature shares many similarities to the heating pattern of driven in the photosphere acoustic waves (Kuźma et al 2019) and 2.5D Alfvén waves (Kuźma et al 2020).…”

“…The obtained value of heating rate is also one order of magnitude too small in comparison with the estimated chromospheric cooling rate which in the middle and upper solar chromosphere attains a value of ∼ 10 −2 erg cm −3 s −1 (Avrett 3D 2-fluid Alfvén waves 9 et al 2015). This scenario may change if we take non-linear Alfvén waves into consideration (Kuźma et al 2020).…”

“…Recently published numerical results strongly suggest that ion-neutral collisions can affect the transport of energy and its dissipation in a partially-ionized chromosphere. For instance, Soler et al (2019), using a photospheric broadband driver that contains a spectrum of frequencies corresponding to wave periods ranging from 3.33 s up to 2.78 h, in- and Kuźma et al (2020) revealed a rise of the plasma temperature in the solar atmosphere resulting from the collisional heating. The two-fluid effects also play an important role when non-linear effects become important, particularly in the context of wave damping and plasma heating (e.g., Kuźma et al 2019;Wójcik et al 2020;Zhang et al 2021).…”

Slow magnetoacoustic waves in gravitationally stratified two-fluid plasmas in strongly ionized limit

“…Although collisions between various species are important for various aspects related to partially ionised plasmas such as thermalisation of the plasma, various ionisation/recombination processes, appearance of thermal layers for shock waves in partially ionised plasmas, etc. (Shanmugasundaram and Murty 1978, Mathers 1980, Terradas et al 2015, Martínez-Gómez et al 2018, Ballai 2019, Kuzma et al 2020, the short-range collisions between neutrals and charged particles are important as only this physical mechanism ensures that neutrals are a constituent part of the plasma. Given the large mass difference ★ E-mail: aalharbi8@sheffield.ac.uk between electrons and ions, effective way for transferring energy and momentum occurs only via collisions between ions and neutrals.…”

The separation of ions and fluxes in nonlinear ion-acoustic waves

“…( 4) and ( 21) in Eq. ( 17) written in the moving frame of reference (5), we obtain second-order ordinary differential equation (11) with the electric charge density ρ eii (ϕ) given by…”