Cascade of whistler turbulence: Particle‐in‐cell simulations

Abstract

A two‐dimensional electromagnetic particle‐in‐cell simulation in a magnetized, homogeneous, collisionless plasma of electrons and protons has been carried out, demonstrating a forward cascade of whistler turbulence. Enhanced magnetic fluctuation spectra are initially imposed with −0.2 < k ∥ c / ω e < 0.2 and −0.2 < k ⊥ c / ω e < 0.2 where the directional subscripts denote directions relative to the background magnetic field B o and c / ω e is the electron inertial length. The late‐time evolution of the simulation shows a cascade of magnetic fluctuation energy to shorter wavelengths; furthermore, the spectrum is anisotropic with more fluctuation energy at a given wavenumber perpendicular to B o than at the same wavenumber parallel to the background field. The late‐time electron velocity distribution shows a magnetic‐field aligned signature due to the Landau resonance of the obliquely propagating whistlers.