Whistler turbulence in high beta plasma: Particle-in-cell simulation

Abstract

Solar wind observations show steeper magnetic spectra at electron scales than at proton scales. Earlier two-dimensional particle-in-cell (PIC) simulations of whistler turbulence in low beta plasmas demonstrated a cascade of magnetic fluctuation energy which is forward and anisotropic with preferential transfer of energy to wavevectors quasi-perpendicular to the background magnetic field. These simulations showed a magnetic wavenumber spectrum with a power-low index similar to that observed in the solar wind at electron scales. Here for the first time two-dimensional PIC simulation of whistler turbulence in high beta as observed in the solar wind at 1AU is carried out in a collisionless, homogeneous, magnetized plasma. Our simulation results show that the wavenumber anisotropy and the power-law index in high beta plasma are more isotropic and steeper than those in lower beta plasmas. Electron Landau and cyclotron damping become more effective at higher beta plasmas, so this simulation, that corresponds to solar wind conditions at 1 AU, suggests that electron kinetic effects are important in determining the properties of whistler turbulence in the high beta regime.