Nonlinear Oblique Whistler Wave in Solar Wind Plasma in the Vicinity of Earth’s Foreshock

Finite difference time domain (FDTD) simulations are applied to study the amplification and decay of nonlinear whistler waves in solar wind plasma in the vicinity of Earth’s foreshock. The considered plasma system comprises of streaming, hot protons and electrons. The main emphasis is on the feedback process between particle streaming and triggered nonlinear waves. It is determined that accelerated and parallel streaming electrons and protons significantly amplify whistler waves and lead to highest pitch angle scattering rates for electrons. The protons mostly show wave like smooth pitch angle scattering rates. However, electrons pitch angle scattering rates are characterized by random and sudden peaks. The counter streaming electrons and protons damp the whistler waves and exhibit negligible effects on the pitch angle scattering rates. Whistler waves at smaller propagation angles increases electron pitch angle scattering rates. Contrarily the whistler waves at high propagation angles resulted in the reduction of pitch angle scattering rates for electrons. The highest pitch angle scattering rates are noticed for protons in plasma system dominated by electrons streaming speeds. Our results may be important for comprehensive understanding of nonlinear turbulence (because whistler waves have a band of frequencies and some of the frequencies will be in resonance with particles cyclotron motion) in the neighborhood of Earth’s foreshock.