Speaker
Manuel Collados
(Instituto de Astrofisica de Canarias)
Description
The deepest layers of the solar atmosphere are only
partially ionised. As a result,
the presence of neutrals cannot be neglected and they can
influence magnetic
structures in various aspects. Neutrals do not feel directly
the effects of the
Lorentz force and are only sensitive to it through
collisions with charged particles.
The net effect is that these collisions have an impact on
the electric currents and,
as a consequence, they can influence the magnetic
equilibrium, they can give rise to
magnetic instabilities, they can have an impact on wave
propagation and can give rise
to a number of energy dissipation mechanisms. Under a
single-fluid approach, all
these effects appear through the generalised Ohm's law, in
which a number of
non-ideal terms appear. These terms have different
importance, and at different
spatial and temporal scales, depending on the magnetic
configuration and at different
heights on the solar atmosphere. Two-fluid or multi-fluid
approaches have also been
attempted. Even if there are no definite evidences yet of
the effects induced by the
presence of neutrals on some solar phenomena, there is an
increasing opinion that
observations and numerical simulations with higher and
higher spatial resolution are
required to identify them. In this contribution, all these
aspects will be reviewed
under three points of view: advances under purely
theoretical analyses, progress in
numerical simulations and attempts to observationally
determine the different
behaviour of the neutral and charged components of the solar
plasma.
Primary author
Manuel Collados
(Instituto de Astrofisica de Canarias)
