[P-EM11] Dynamics of the Inner Magnetospheric System

[PEM11-11] Cross-energy coupling between magnetosonic waves to electromagnetic ion cyclotron waves through cold ion heating

*浅村 和史¹、小路 真史²、三好 由純²、笠原 禎也³、笠羽 康正⁴、熊本 篤志⁴、土屋 史紀⁴、松田 昇也³、松岡 彩子⁵、寺本 万里子⁶、風間 洋一⁷、篠原 育¹ (1.宇宙航空研究開発機構宇宙科学研究所、2.名古屋大学宇宙地球環境研究所、3.金沢大学自然科学研究科、4.東北大学理学研究科、5.京都大学理学研究科、6.九州工業大学工学研究科、7.台湾中央研究院)

キーワード：磁気音波、電磁イオンサイクロトロン波、イオン加熱、波動粒子相互作用解析

Fast magnetosonic waves (MSWs) are commonly observed in the equatorial inner magnetosphere. Past numerical simulations show that MSWs can accelerate low-energy ions through cyclotron resonance, although the observational evidence is still unclear. The Arase satellite found an event of perpendicular heating of low-energy protons simultaneously with enhancement of MSWs. Using the wave-particle interaction analysis (WPIA), we obtain direct evidence of energy transfer from the observed MSWs to the low-energy (26 – 725 eV) protons. We found these protons give their energies to electro-magnetic ion cyclotron (EMIC) waves with frequencies just below the local proton cyclotron frequency. Since MSW is excited by a ring-like distribution of ions, this analysis suggests that a part of energies of the ring current ions is transferred to the low-energy ions through excitation and damping of MSWs in the inner magnetosphere, and then, a part of the transferred energies is spent to excite high-frequency EMIC waves.