  This work consists of two parts: the first devoted to the study of the
heating of the magnetically confined Solar Corona, and the second to the
acceleration of the Slow Solar Wind.
  Direct 3D reduced MHD simulations are presented. They model the heating of
coronal loops in the solar atmosphere via the tangling of coronal field lines
by photospheric footpoints motions within the framework of the "Parker
scenario". We have derived scalings of physical quantities with loop length,
and the ratio of photospheric to coronal Alfven velocities. The development of
a turbulent dynamics makes the dissipation rate independent of the Reynolds
number. The dynamics in physical space are desribed by weak turbulence, which
develops when an MHD system is embedded in a strong axial magnetic field.
  The slow wind originates in and around the coronal streamer belt. The LASCO
instrument onboard the SOHO spacecraft has observed plasma density enhancements
forming beyond the cusp of a helmet streamer. Previous theoretical models for
the formation and initial motion of these density enhancements are improved.
  The average expansion suffered by a parcel of plasma propagating outward, and
the diamagnetic force due to the overall magnetic field radial gradients are
now included. It is found that the magnetized wake configuration is resistively
unstable, that an outward accelerating magnetic island develops at the center
of the streamer, and that density enhancements occur within the magnetic
islands. The values of the acceleration and density contrasts can be in good
agreement with LASCO observations, provided the spherical divergence of the
magnetic lines starts beyond a critical distance from the Sun. This result
provides a constraint on the topology of the magnetic field.
