This project aims to understand the key physical laws and processes underlying a range of basic phenomena observed in the solar atmosphere. We will study the emergence of magnetized plasma from the solar interior, the propagation of waves and shocks in the atmosphere, and the stability of structures (prominences, photospheric magnetic flux tubes) where the plasma is only marginally ionized.

Our research is based on theoretical modeling, it combines plasma physics and radiation transfer, and relies to a large extent on multidimensional numerical experiments and simulations, especially those that can be obtained using state-of-the-art, massively parallel computer codes. As part of this effort, the project will carry out the detailed calculation of the radiation intensity emerging in different wavelengths from the computational boxes. With the results, observational proxies for comparison with actual observations can be produced; in this way support can be given to the instrument planning for the European Solar Telescope (EST) and for future space missions. The emerging spectra will also be used for an in-depth study of the diagnostic potential of photospheric and chromospheric lines, including NLTE aspects and the Hanle effect. The project includes the enlargement and completion of two large, massively parallel computer codes that are being developed at the IAC: the Mancha code, a multifluid radiation- hydrodynamics code, and Porta, a non-LTE radiative transfer code for the calculation of the intensity and polarization of spectral lines. Further, we will be using the radiation magnetohydrodynamics code Bifrost, possibly the most advanced code for modeling processes involving the layers from the convection zone to the corona. A central component in the project is the study of the very different levels of ionization of the plasma in the various domains of the solar atmosphere. The plasma is partially ionized in the low atmosphere, and the presence of neutrals leads to enhanced dissipation and diffusion which can cause important effects in the structure and time evolution of the chromosphere and of individual photospheric objects (like small flux tubes and sunspots). We expect modifications in our understanding of the heating of the chromosphere, the dynamics of fibrils, jets, prominences and spicules, and in the emergence of magnetized plasma from the solar interior. The study of these effects is at an initial stage of development in solar physics; this projects aims to make basic contributions, not only via individual studies, but also through the fact that the Mancha code is especially designed to cope with the effects of the partial ionization of the plasma.