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-P31] Two-dimensional Particle Simulations of Oblique Whistler-mode Instability

*野儀 武志1大村 善治1 (1.京都大学 生存圏研究所)

We perform two-dimensional electromagnetic particle simulations to study basic characteristics of whistler-mode
wave particle interaction involved in chorus emissions propagating oblique to the static magnetic field. We assume
a simple periodic (x, y) system with the magnetic field taken in the x-direction. Assuming energetic electrons
with an anisotropic bi-Maxwellian velocity distribution function, we first test the linear whistler-mode instability
driven by temperature anisotropy to confirm the numerical property of the simulation code. With the electrostatic
components parallel to the magnetic field, which have been neglected in the previous simulation studies on chorus
emissions, we find the linear phase of the instability is much affected by the Electrostatic thermal fluctuations.
It is necessary to put many super-particles in a grid cell to suppress the thermal fluctuation. With 30,000 particles
per cell, we have confirmed a good agreement of the wave growth in the parallel direction with the linear growth
rate. We next put an array of antennas with obliquely aligned to uniform magnetic field, and oscillate the antenna
current with a variable frequency below the electron cyclotron frequency to excite a large amplitude whistler-mode
wave obliquely propagating to the static magnetic field. In addition to the nonlinear trapping of energetic electrons
through the cyclotron resonance, another nonlinear trapping of electrons by the Landau resonance takes place.
Structures of the nonlinear trapping potentials changes with a varying frequency, affecting the efficiency of
energy transfer between the wave and energetic electrons. We study nonlinear evolution of the wave packet, and
competing processes of both resonances in accelerating the energetic electrons to higher energies.