Statistical Survey of Collisionless Dissipation in the Terrestrial Magnetosheath

Abstract:

Kinetic dissipation of turbulence is an important physical process occurring in interplanetary space plasmas. Using in situ data from the Magnetospheric Multiscale (MMS) Mission in the quasi-parallel and quasi-perpendicular shocked plasma in the Earth's magnetosheath, we investigate in detail the statistics of kinetic dissipation, based on analysis of the Vlasov-Maxwell equations. These equations give a general description of transfer of thermal energy, flow energy, and electromagnetic energy in collisionless plasma, including both spatial transport and conversion between forms. In particular, we focus on the processes that convert flow energy into internal energy, separately for both protons and electrons. Applying those results to MMS burst data obtained in the weakly collisional terrestrial magnetosheath plasma, it is possible to quantify contributions to dissipation from pressure-dilatation, and from pressure-strain interactions, for both plasma species. We also employ a simple spatial filtering approach to quantify plasma heating at large and small scales. The analysis is carried out for 50 selected data intervals and statistical distributions of the results are obtained.