Energy dissipation by whistler turbulence: Three-dimensional particle-in-cell simulations

Abstract

Three-dimensional particle-in-cell simulations of whistler turbulence are carried out on a collisionless, homogeneous, magnetized plasma model. The simulations use an initial ensemble of relatively long wavelength whistler modes and follow the temporal evolution of the fluctuations as they cascade into a broadband, anisotropic, turbulent spectrum at shorter wavelengths. For relatively small levels of the initial fluctuation energy ɛ_e, linear collisionless damping provides most of the dissipation of the turbulence. But as ɛ_e and the total dissipation increase, linear damping becomes less important and, especially at β_e ≪ 1, nonlinear processes become stronger. The PDFs and kurtoses of the magnetic field increments in the simulations suggest that intermittency in whistler turbulence generally increases with increasing ɛ_e and β_e. Correlation coefficient calculations imply that the current structure dissipation also increases with increasing ɛ_e and β_e, and that the nonlinear dissipation processes in these simulations are primarily associated with regions of localized current structures.