Non-Steady Reconnection In Stratified Atmospheres : Applications To the Solar Environment

The magnetic reconnection process has a key-role in plasma physics. Though being over-studied for decades, there are several aspects of this fundamental mechanism that remain unclear. Nevertheless, magnetic field line reconnection is often invoked to explain in part or completely the complex evolution of several astrophysical and heliospheric structures. In particular, fast reconnection mechanisms are required in a huge variety of phenomena, for instance in solar explosive processes where erupting prominences, c.m.e.s' onset and flares' emissions are different actors in a unique scenario where reconnection plays a critical role. A strong interest is focused on the conditions for the transition between different reconnection regimes: in particular, the evolution of a current-sheet can enter a stage where the same process repeats over and over leading to a turbulent phase with the development of small scale structures interacting each other, or to a possible scale-free fractal reconnection process. This work presents a numerical analysis of such a picture in the MHD approximation where an initial current-sheet equilibrium configuration is considered and its dynamics is followed throughout the formation and the interaction of reconnection jets. The evolution of the system is observed to be driven from the initial condition through several states to a final chaotic configuration. The model is hence applied to different structures observed in the solar atmosphere.

Publication year:2008