  The last 60 years of space exploration have shown that the interplanetary
medium is continually perturbed by a myriad of different solar winds and storms
that transport solar material across the whole heliosphere. If there is a
consensus on the source of the fast solar wind that is known to originate in
coronal holes, the question is still largely debated on the origin of the slow
solar wind (SSW). The recent observations from the Parker Solar Probe mission
provide new insights on the nascent solar wind. And a great challenge remains
to explain both the composition and bulk properties of the SSW in a
self-consistent manner. For this purpose we exploit and develop models with
various degrees of complexity. This context constitutes the backbone of this
thesis which is structured as follows: we exploit the first images taken by the
Wide-Field Imager for Solar PRobe (WISPR) from inside the solar corona to test
our global models at smaller scales, because WISPR offers an unprecedented
close-up view of the fine structure of the nascent SSW. This work provides
further evidence for the transient release of plasma trapped in coronal loops
into the solar wind, that we interpret by exploiting high-resolution
magneto-hydrodynamics simulations. Finally we develop and exploit a new
multi-specie model of coronal loops called the Irap Solar Atmosphere Model
(ISAM) to provide an in-depth analysis of the plasma transport mechanisms at
play between the chromosphere and the corona. ISAM solves for the coupled
transport of the main constituents of the solar wind with minor ions through a
comprehensive treatment of collisions as well as partial ionization and
radiative cooling/heating mechanisms near the top of the chromosphere. We use
this model to study the different mechanisms that can preferentially extract
ions according to their first ionization potential (FIP) from the chromosphere
to the corona.
