  We investigate the effects of interactions between ions and neutrals on the
chromosphere and overlying corona using 2.5D radiative MHD simulations with the
Bifrost code. We have extended the code capabilities implementing ion-neutral
interaction effects using the Generalized Ohm's Law, i.e., we include the Hall
term and the ambipolar diffusion (Pedersen dissipation) in the induction
equation. Our models span from the upper convection zone to the corona, with
the photosphere, chromosphere and transition region partially ionized. Our
simulations reveal that the interactions between ionized particles and neutral
particles have important consequences for the magneto-thermodynamics of these
modeled layers: 1) ambipolar diffusion increases the temperature in the
chromosphere; 2) sporadically the horizontal magnetic field in the photosphere
is diffused into the chromosphere due to the large ambipolar diffusion; 3)
ambipolar diffusion concentrates electrical currents leading to more violent
jets and reconnection processes, resulting in 3a) the formation of longer and
faster spicules, 3b) heating of plasma during the spicule evolution, and 3c)
decoupling of the plasma and magnetic field in spicules. Our results indicate
that ambipolar diffusion is a critical ingredient for understanding the
magneto-thermo-dynamic properties in the chromosphere and transition region.
The numerical simulations have been made publicly available, similar to
previous Bifrost simulations. This will allow the community to study realistic
numerical simulations with a wider range of magnetic field configurations and
physics modules than previously possible.
