Amplification of Electrostatic Wave at the Cost of Kinetic Alfvén Wave Turbulence Energy in Auroral Zone

Abstract

The low-frequency electromagnetic kinetic Alfvén (KAW) wave is among the most significant waves in the Earth's magnetospheric plasma environment. This study investigates the generation process of high-frequency electrostatic and non-resonant upper-hybrid (UH) waves at the expense of kinetic Alfvén waves in the Earth's auroral zone. The plasma particles that sustain long-term phase alignment with the kinetic Alfvén wave turbulent field are accelerated. The accelerated plasma particles may transfer energy and momentum to the unstable high-frequency wave via a modulation field. Considering a Maxwell-Boltzmann distribution function and using the Vlasov-Poisson system of equations, fluctuating parts of distribution functions resulting from the resonant KAW, modulated wave, and nonlinear upper-hybrid wave are estimated. Data available from various space probes in Earth's magnetosphere are used to calculate the growth rates of the upper-hybrid wave from nonlinear dispersion relations. The calculations demonstrate that the amplification of upper-hybrid wave is possible at the expense of kinetic Alfvén wave turbulent energy.