The solar wind provides a fascinating laboratory for the investigation of a wide range of plasma physical processes, such as, e.g., turbulence, intermittency, magnetic reconnection and plasma heating.
One of the key aspects for a deep understanding of these phenomena is the plasma behaviour at small scales.
This session is intended as a discussion forum on the role played by small scales in solar wind plasma dynamics and/or evolution.
Processes occurring at large scales are anyhow responsible for the generation of small scale kinetic fluctuations and structures that in turn have important feedback on the global system evolution.
For instance, magnetic reconnection occurring at non-MHD scales is responsible for global changes of the magnetic field topology. Reconnection in turbulence is linked to the small scale solar wind discontinuities. In particular, recent studies have shown that current sheets produced by turbulence cascade and discontinuities observed in the solar wind have very similar statistical properties and they are connected to intermittency.
Furthermore, the solar wind offers the best opportunity to study directly collisionless plasma phenomena and to attempt to address fundamental questions on how energy is transferred from large to small scales and how it is eventually dissipated. In fact, in-situ observations have shown that the temperature diminishes slower than what is predicted by an adiabatic expansion. This implies that a mechanism of heating is locally at work. Kinetic effects (such as wave-particle
resonant interaction) that presumably govern the short-scale dynamics
are considered the best candidates to replace collisional processes in "dissipating" the energy at small wavelengths and in heating the plasma.
On the other hand, recent studies suggest that dispersive effects dominate the small-scale domain, instead of dissipative effects. This represents one of the most debated subject.
The aim of this session is to review the state of the art on these topics and their possible implications on space weather, both under theoretical and numerical standpoints, and comparing theoretical results with recent observations.