Formation of coherent structures in kinetic simulations of collisionless turbulence

Abstract:

We discuss recent large-scale kinetic simulations of collisionless turbulence in two environments, the solar wind and the Earth’s magnetosheath. Formation of copious coherent structures is observed in both cases, despite the facts that the geometry, characteristic plasma parameters, and driving mechanisms are drastically different between the two systems. In addition to the traditional planar current sheets, other types of coherent current structures have been observed in 3D fully kinetic simulations with initial conditions relevant to the solar wind. These structures are discussed in detail. In 3D global hybrid simulations of the interaction between solar wind and planetary magnetospheres, the foreshock dynamics driven by reflected ions is shown to have a significant impact on the structure of the bow shock, as well as on the magnetosheath turbulence. A complicated interaction between turbulence, bow shock, and global flow leads to global perturbations in the Earth’s magnetosphere.