日本地球惑星科学連合2019年大会

講演情報

[J] 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-EM17] 宇宙プラズマ理論・シミュレーション

2019年5月30日(木) 10:45 〜 12:15 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:梅田 隆行(名古屋大学 宇宙地球環境研究所)、天野 孝伸(東京大学 地球惑星科学専攻)、成行 泰裕(富山大学人間発達科学部)、中村 匡(福井県立大学)

[PEM17-P01] 高速イオンによる低域混成波不安定性とその非線形発展に関する粒子シミュレーション

*小谷 翼1樋田 美栄子2森高 外征雄2田口 聡1 (1.京都大学大学院理学研究科、2.核融合科学研究所)

キーワード:低域混成波不安定性、イオンサイクロトロン放射、非線形発展、粒子シミュレーション

Instabilities driven by energetic ions are important issues both for space plasmas and magnetic fusion plasmas. Radio Frequency (RF) waves in the range from the ion cyclotron frequency to the lower hybrid resonance frequency are often observed during the period of neutral beam injection (NBI) in Large Helical Device (LHD) plasmas. The experimental results showed that the peak frequency in the Lower Hybrid Wave (LHW) region has a positive correlation with the electron density and the ion cyclotron emissions (ICEs) have much larger amplitudes than LHW. These waves can be excited by instabilities due to energetic ions generated by the NBI perpendicular to the magnetic field.

Using a one-dimensional, electromagnetic, Particle-In-Cell (PIC) code, we study instabilities driven by energetic ions assuming that the energetic ions have a non-Maxwellian ring-like distribution in the velocity space perpendicular to the magnetic field. This PIC code enables us to self-consistently simulate full dynamics of electrons and ions and evolution of electromagnetic fields, using the full Maxwell's equations and the equations of motion of particles. We focus on the nonlinear evolution of LHW and ICEs caused by continuous energetic-ion injection into a plasma.

The simulation results are as follows. After the rapid growth of the LHW in the early stage, the ICEs gradually become intense. Finally, the ICEs have larger amplitudes than LHW.