Turbulence is ubiquitous in space and astrophysical plasmas where it plays a key role in all\u00a0physical phenomena such as mass transport, energy dissipation and particle heating. Unlike\u00a0neutral fluids, where energy dissipation occurs via viscous effects originating from particle\u00a0collisions at the microscopic level, most of space plasmas are collisionless (or weakly\u00a0collisional). Most of the relevant interactions are therefore in the form of field-particle\u00a0interactions between the charged particles and the electromagnetic fields. Among the near-Earth space plasmas the solar wind (SW) is certainly the most accessible astrophysical\u00a0plasma to in-situ measurements. Observations of SW turbulence have usually emphasized\u00a0magnetohydrodynamic (MHD) scales where the Kolmogorov scaling f^-5\/3 of the magnetic\u00a0spectra is frequently observed. These spectra are thought to result from strongly nonlinear\u00a0interacting Alfv\u00e9n waves. However, the question as to how turbulence of the MHD scales\u00a0terminates its cascade at smaller (kinetic) scales is still hotly debated. Answering this\u00a0question is indeed fundamental to understanding the processes of particle acceleration and\u00a0plasma heating in the SW and in other astrophysical plasmas. Two possible channels of\u00a0energy dissipation are currently subject to intensive research work. The first channel is\u00a0dissipation via collisionless kinetic effects such as resonant field-particle interactions (e.g.\u00a0cyclotron and\/or Landau resonances) or non-resonant effects such as Finite Larmor Radius\u00a0effects (FLRs). The second channel is dissipation through magnetic reconnection occurring\u00a0within current sheets that form naturally in turbulent plasmas.
\nThis project aims at studying each of these mechanisms of energy dissipation. We will use a multiple approach that combines in-situ\u00a0fields and particles data available from the multispacecraft missions, and numerical\u00a0simulations to model the complex behavior of turbulence cascade at kinetic scales where it\u00a0is dissipated. The observations will be made using mainly data from the Cluster and Themis\u00a0satellites, which offer a unique chance to identify and to characterize three-dimensional (3D)\u00a0spatial plasma structures. Moreover, their high time resolution E and B measurements\u00a0makes it possible to probe into the smallest scales ever explored in the SW. The simulation\u00a0work will be done using different codes, Hall-MHD, PIC and Vlasov, available in the group.<\/p>\n","protected":false},"excerpt":{"rendered":"
Turbulence is ubiquitous in space and astrophysical plasmas where it plays a key role in all\u00a0physical phenomena such as mass transport, energy dissipation and particle heating. Unlike\u00a0neutral fluids, where energy dissipation occurs via viscous effects originating from particle\u00a0collisions at the … Continue reading