[P-EM13] Dynamics of the Inner Magnetospheric System

[PEM13-P18] 双極子化イベント中の粒子ダイナミクスの数値モデル化

*ギルギス キロロス¹、羽田 亨¹、汪 愷悌²、大塚 史子³、吉川 顕正^1,4 (1.九州大学　国際宇宙惑星環境研究センター、2.淡江大学　航空宇宙工学科、3.九州大学　総合理工学研究院、4.九州大学　理学研究院 地球惑星科学部門)

キーワード：双極子化、サブストーム、テスト粒子シミュレーション、粒子ダイナミクス

We developed a test particle simulation code to examine the particle dynamics during three dipolarization events during substorm time detected by the THEMIS mission. We computed the trajectories and the acceleration levels of 20 keV electrons, protons, and oxygen ions with different initial pitch angles and L-shells by implementing the guiding center model and the full Lorentz particle motion, utilizing an auto-switch between both methods based on the adiabatic trapping condition. We adopted the Tsyganenko model (TS05) and the IGRF-12 to reproduce the time-varying magnetic field model with the corresponding inductive and polarized electric fields. Furthermore, we included the effects of the pitch angle scattering and the substorm current wedge current model.
Our preliminary simulation results confirmed the particle energization in the nighttime magnetosphere during dipolarization. The inclusion of a strong pitch angle scattering model resulted in a 10% protons injection in the outer radiation belt region, whereas the substorm current wedge model led to a 20% protons injection.
Our findings highlight the substorm effects on the radiation belt population and its impact on the near-Earth environment.