Plasmas may be investigated either at the macroscopic fluid/MHD (magnetohydrodynsmics) level or at the microscopic kinetic one. The dynamics is invariably nonlinear: waves develop into shocks while turbulence transports energy from the largest to the smallest scales, where dissipation occurs in thin current sheets. Both shocks and reconnection events are sources of plasma heating and non-thermal particle acceleration.

The solar atmosphere is certainly the astrophysical environment in which the importance of magnetic fields manifests itself in the most spectacular ways. Its outer layer, the corona, is a tenuous and very hot plasma (millions of degrees), strongly dynamic and dominated by magnetic loops and erupting prominences. It is also the source of the outflowing solar wind, reaching the Earth. 

The solar wind and heliospheric plasma parameters are measured in situ by dedicated missions, both ions and electrons exhibit kinetic deviations from the thermal equilibrium, such as supra-thermal tails elongated in the direction of the local magnetic field. The solar wind interacts with the Earth's magnetosphere, giving rise to several space weather phenomena, which can be predicted.

The plasma of some astrophysical sources may exhibit extreme characteristics, requiring a relativistic treatment. For instance, fast-spinning magnetised neutron stars produce a high Lorentz factor wind of electron-positron pairs, confined by the surrounding supernova remnant and forming a so-called Pulsar Wind Nebula (e.g. the Crab nebula), emitting non-thermal synchrotron radiation over the entire electromagnetic spectrum. 

The plasma sorrounding compact objects, such as black holes and neutron stars, must be treated using General Relativistic MHD, in which Newtonian gravity is replaced by Einstein's theory. In our group we have developed pioneering methods and codes (ECHO) for such studies, for example with applications to the plasma in accretion disks around black holes (e.g. dynamo processes).

The theoretical investigation of the plasma dynamics, at all scales, is mainly carried out through numerical simulations. Within our research group we have developed numerical methods and codes, both in the fluid/MHD or kinetic regimes, optimised for execution on CPU or GPU-based High Performing Computing (HPC) clusters.