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Research topics

My main research topics concern the solar corona and the Sun-Earth relationships. A large part of my past work concerns the heating of the corona: the solar corona is indeed heated to millions of degrees, and understanding the processes implied in this phenomenon represents one of the most important challenges of solar physics; there are also implications on the physics of the stars in general and for the understanding of the sometimes tumultuous relationships between the Sun and the Earth, especially during solar storms. Another part of my work concerns more specifically the solar wind, which is the extension of the corona to the Earth and the other planets. The solar wind and corona, both highly dynamic and structured by the magnetic field, are also a natural laboratory for the study of plasmas and turbulence. I am especially interested in these objects and topics:

• Magnetic loops of the solar corona:
  • Heating mechanisms, especially including turbulence and small space and time scales, statistics of this heating, profiles of the heating along loops; observational characterization of statistics of heating and turbulence; connection with solar eruptions and space weather.
  • Coupling between these heating mechanisms and the cooling mechanisms, including radiation; production of spectroscopic observables; research of spectroscopic signatures of the coronal mechanisms; comparison with observations.
• Open regions of the corona and the solar wind: heating mechanisms and acceleration of the wind, especially including turbulence; anisotropy of MHD turbulence, and Hall-MHD turbulence in the interplanetary medium.
• Prominences/filaments: detection, characterization, and tracking of filaments until their eruption.
• Applications to other astrophysical problems (stellar physics, interstellar medium...), to theory of turbulence, and to space weather.

Turbulence in a magnetic flux tube: the Shell-Atm numerical code

The Shell-Atm code (Buchlin and Velli 2007, Verdini et al. 2009) is designed to provide fast simulations of MHD turbulence in a volume dominated by a longitudinal magnetic field B₀. Because of this strong field, the turbulent, non-linear dynamics occurs essentially in the planes orthogonal to B₀. The Shell-Atm model consists thus of a set of planes orthogonal to B₀, in which the non-linear dynamics can be modelled, for instance by shell-models. These planes are piled up along B₀, and Alfvén waves propagate between them, allowing the transport of energy from the boundaries of the simulation box.

Shell-Atm has been used in several papers to simulate solar coronal loops, the solar wind, and for theoretical studies of turbulence. The model source code and manual are available from the IAS Gitlab server.