[P-EM12] Dynamics of the Inner Magnetospheric System

[PEM12-08] Particles simulations of whistler-mode triggered emissions with subpacket structures

野儀 武志¹、*大村 善治¹ (1.京都大学生存圏研究所)

キーワード：波動粒子相互作用、ホイッスラーモード波、非線形過程

We perform one-dimensional simulations[1] of whistler-mode triggered emissions to study nonlinear signatures of rising-tone emissions. We assume a parabolic magnetic field and energetic electrons with temperature anisotropy. We oscillate currents with a fixed frequency, 0.3 of electron cyclotron frequency, at the magnetic equator to inject finite amplitude whistler-mode waves. We observe rising-tone triggered emissions with sub-packet structures from 0.3 to 0.75 of electron cyclotron frequency. We find a clear separation of triggered emissions from the triggering waves. The first triggered wave packet is formed with growing wave amplitude and smooth rising-tone frequency over the frequency range 0.3-0.5 of electron cyclotron frequency. The electron hole initially formed at the equator expands spatially to the upstream region. The formation of electron holes takes place in the spatial range with the inhomogeneity factor |S| less than 1. When the frequency approaches to 0.5fce, we find some density modulation of the untrapped resonant particles around the electron holes. The modulation causes oscillations of resonant currents with a frequency of the same order of trapping frequencies, resulting in the generation of sub-packet structures.



[1] Nogi, T., Nakamura, S., & Omura, Y. (2020). Full particle simulation of whistler-mode triggered falling-tone emissions in the magnetosphere. Journal of Geophysical Research: Space Physics, 125, e2020JA027953, https://doi.org/10.1029/2020JA027953.