On the role of ion-scale whistler waves in space and astrophysical plasma turbulence

Abstract

Competition of linear mode waves is studied numerically to understand the energy cascade mechanism in plasma turbulence on ion-kinetic scales. Hybrid plasma simulations are performed in a 3-D simulation box by pumping large-scale Alfvén waves on the fluid scale. The result is compared with that from our earlier 2-D simulations. We find that the whistler mode is persistently present both in the 2-D and 3-D simulations irrespective of the initial setup, e.g., the amplitude of the initial pumping waves, while all the other modes are excited and damped such that the energy is efficiently transported to thermal energy over non-whistler mode. The simulation results suggest that the whistler mode could transfer the fluctuation energy smoothly from the fluid scale down to the electron-kinetic scale, and justifies the notion of whistler turbulence.