Seminar’s Schedule:
15:30 – 15:45 : Welcome and set up
15:45 – 16:30 : Seminar + Q&A
16:30 – 16:45 : Tea, coffee, and discussions
The ultimate fate of turbulence in weakly-collisional plasmas: phase-space cascades, Dr. Oreste Pezzi
Understanding the dynamics of turbulent, weakly-collisional plasmas at kinetic scales is decisive for tackling the fundamental issues of energy dissipation and plasmsa heating. As a result of the weak collisionality, kinetic-scale plasma turbulence naturally generates a large variety of non-equilibrium velocity-space structures in the plasma distribution function. This emerging complexity has been recently envisioned as a turbulent cascade occurring in the entire six-dimensional phase space.
In this talk, I will review some recent results on this topic, mainly obtained by exploiting Eulerian Hybrid Vlasov-Maxwell numerical simulations. By Hermite-decomposing the proton velocity distribution function, I will show that the Hermite spectrum of the velocity distribution function displays a broadband, power-law behavior, whose slope is in agreement with theoretical expectations. The effect of the background magnetic field inducing a velocity-space spectral anisotropy, and the spatial intermittency of the velocity-space activity will be discussed as well. Finally, I will analyze the effect of inter-particle collisions which, despite being in general weak, inhibit the development of velocity-space cascade by dissipating fine velocity structures, thus restoring thermodynamic irreversibility.
Speaker’s short bio:
Oreste Pezzi achieved his undergraduate and master’s degrees at the University of Calabria (Italy), where he also obtained his Ph.D. in 2017. After a first post-doctoral position at the same university, he moved to the Gran Sasso Science Institute (Italy), where he has been post-doctoral researcher for three years. Since 2020, he has been a permanent researcher at the Institute for Plasma Science and Technology of the National Research Council of Italy. His research interests include turbulence in space and astrophysical plasmas and the mechanisms responsible for the transport and energization of particles in these turbulent environments.