JpGU-AGU Joint Meeting 2017

講演情報

[EE] ポスター発表

セッション記号 P (宇宙惑星科学) » P-EM 太陽地球系科学・宇宙電磁気学・宇宙環境

[P-EM16] [EE] Physics of Inner Magnetosphere Coupling

2017年5月24日(水) 13:45 〜 15:15 ポスター会場 (国際展示場 7ホール)

コンビーナ:Danny Summers(Memorial University of Newfoundland)、Jichun Zhang(University of New Hampshire Main Campus)、海老原 祐輔(京都大学生存圏研究所)、桂華 邦裕(東京大学大学院理学系研究科地球惑星科学専攻)、Aleksandr Y Ukhorskiy(Johns Hopkins University Applied Physics Laboratory)、Dae-Young Lee(Chungbuk Natl Univ)、Yiqun Yu(Beihang University)、三好 由純(名古屋大学宇宙地球環境研究所)

[PEM16-P29] Nonlinear dynamics of resonant particles interacting with coherent waves and comparison with quasi-linear theory

*飛田 美和1大村 善治1 (1.京都大学生存圏研究所)

キーワード:wave-particle interaction, nonlinear wave trapping, particle acceleration

We perform test particle simulations of charged particles in an external constant electric field and electrostatic wave fields. We solve equations of motion, which take the same form as the pendulum equation, and we study nonlinear dynamics of particles with different values of inhomogeneity factor S defined as a ratio of the wave amplitude to the background electrostatic field. The target of the present study is to understand nonlinear dynamics of resonant particles interacting with coherent waves in space plasmas. Electromagnetic waves such as whistler-mode chorus, hiss emissions, and electromagnetic ion cyclotron (EMIC) waves in the inner magnetosphere contain structures of coherent waves with various discrete frequencies. Their interaction with resonant particles can be approximated by the nonlinear pendulum equation, or the equations of motion for a charged particle in a one-dimensional electrostatic wave potential. Conventionally, particle scattering and energization are studied as particle diffusion by incoherent waves without any background field causing adiabatic variation of the drift velocity. However, this model, called quasi-linear diffusion model, cannot explain “super diffusion”, referring to MeV energization and precipitation of particles in a few minutes, found in observations of chorus, hiss, and EMIC waves. To describe the super diffusion with the simplified electrostatic model, we introduce the external constant field, which corresponds to an inhomogeneous magnetic field causing adiabatic motion such as mirror motion. All particles are accelerated uniformly and constantly as an adiabatic motion, and they are dramatically heated by scattering and/or nonlinear trapping through resonant interaction with the waves. The present simulation model demonstrates the super diffusion due to coherent waves and the external field.