[P-EM17] 宇宙プラズマ科学

[PEM17-12] 高速イオンが駆動する低域混成波-イオンバーンスタイン波不安定性の閾値解析

*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、イオンバーンスタイン波、高速イオン、不安定性解析

Taking into account the thermal effects, the lower hybrid wave can be considered as a type of ion Bernstein wave. Assuming that energetic ions, as the driving source of these waves, have a ring-like velocity distribution characterized by the delta function, the instability can be determined by the only four parameters: the ion-to-electron mass m_i/m_e, the ratio of the electron plasma frequency to the electron gyro frequency ω_pe/Ω_e, the ratio of the energetic ion velocity to the bulk ion thermal velocity u_⊥/v_ti, and the density ratio of energetic ions to electrons n_h/n_e. There are many previous studies to investigate a lower hybrid and ion Bernstein wave instability, but most of them used limited parameters to analyze the instability.

In this study, we perform parametric instability analyses for lower hybrid and ion Bernstein waves driven by energetic ions. We consider these waves propagating exactly perpendicular to the magnetic field. We analyze the instability threshold (n_h/n_e) for the two parameters (ω_pe/Ω_e and u_⊥/v_ti ) in a hydrogen-electron (m_i/m_e=1836) plasma.