Energy Transfer in Plasma Turbulence: From Macro to Micro Scales

For a weakly collisional or collisionless plasma, the Vlasov-Maxwell equation is an appropriate limit. The problems of energy transfer and dissipation in plasmas are addressed within the framework of the Vlasov approximation and, in particular there are essentially basic points which are cross-scale energy transfer flux due to subgrid-scale stress, the work done by electric field on charged particles, and the pressure tensor work (pressure-strain interaction). The associations and differences that exist among these energy transfer and dissipation surrogates were investigated in detail through hybrid Vlasov-Maxwell (HVM) simulation. They are found to be dominant at different scales, and are spatially located in proximity to each other even if their point-wise correlation may be weak. These results, in conjunction with previous studies based on numerical simulations and observations, provide a way to clarify the key steps of energy transfer from macroscopic magnetohydrodynamic (MHD) scales to kinetic scales.