[P-EM17] Space Plasma Science

[PEM17-02] Electromagnetic particle simulation of nonlinear wave growth process of whistler-mode hiss emissions in the magnetosphere

*YIN ZHENXING^1,2, Yoshiharu Omura^1,2, Yikai Hsieh^1,2 (1.KYOTO UNIVERSITY, 2.Research Institute for Sustainable Humanosphere)

Keywords:nonlinear wave growth, whistler-mode hiss, magnetospheric plasma

We perform a series of electromagnetic particle simulations in the magnetospheric plasma for studying the nonlinear wave growth of hiss emissions. We examine dependency of the nonlinear growth rates on the gradient of the background magnetic field by varying the gradient of the background magnetic field from zero. At the same time we add a frequency band filter to focus on specific frequency range.
We find that in the case of the zero gradient the wave amplitude attains the smallest value compared with other cases of finite gradients. There is an optimum value with which wave amplitude grows to the largest value. To gain a deeper insight into this phenomenon, we compute and visualize both the growth rate and nonlinear growth rate throughout the process of wave generation and propagation. We observe a remarkable growth rate in the wave generation process at the system's boundary. Interestingly, we find that this growth rate remained nearly constant with no apparent variations, even when we manipulated the background magnetic field gradient. The investigation into whether the amplitude of the wave exhibits linear or nonlinear growth, or if it assumes nonphysical behavior during this process, constitutes a compelling topic for future research.