Whistler turbulence at variable electron beta: Three‐dimensional particle‐in‐cell simulations

Abstract

Three‐dimensional particle‐in‐cell (PIC) simulations of whistler turbulence at three different initial values of βe are carried out on a collisionless, homogeneous, magnetized plasma model. The simulations begin with an initial ensemble of relatively long‐wavelength whistler modes and follow the temporal evolution of the fluctuations as wave‐wave interactions lead to a forward cascade into a broadband, turbulent spectrum at shorter wavelengths with a wave vector anisotropy in the sense of k⟂>k∥. Here ⟂ and ∥ denote directions perpendicular and parallel to the background magnetic field, respectively. In addition, wave‐particle interactions lead to fluctuating field dissipation and electron heating with a temperature anisotropy in the sense of T∥>T⟂. At early times, the wave‐wave cascade dominates energy transport, whereas wave‐particle Landau damping dominates at late simulation times. Larger values of βe correspond to a faster forward cascade in wave number and to a faster rate of electron heating, as well as to a less anisotropic wave vector distribution and to a less anisotropic electron velocity distribution.