日本地球惑星科学連合2019年大会

講演情報

[E] 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-EM11] Dynamics of Magnetosphere and Ionosphere

2019年5月29日(水) 13:45 〜 15:15 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:中溝 葵(情報通信研究機構 電磁波研究所)、尾崎 光紀(金沢大学理工研究域電子情報学系)、藤本 晶子(九州工業大学)、堀 智昭(名古屋大学宇宙地球環境研究所)

[PEM11-P13] Examining Minimum Cyclotron Resonant Electron Energy of EMIC Waves with MMS

*Si Liu1 (1.Changsha University of Science and Technology)

キーワード:EMIC waves, minimum resonant electron energy, wave vector, phase differencing

Electromagnetic ion cyclotron (EMIC) waves can be in cyclotron resonance with relativistic electrons, causing relativistic electron precipitation. The four ideal Magnetospheric Multiscale (MMS) spacecraft provide great opportunity to directly calculate the wave vector k of EMIC waves by phase differencing technique and hence estimate the minimum resonant energy by the resonance condition. Deriving a simplified analytic solution, we find that the phase differencing method can still provide an estimate of the dominant wave number when a finite wave number spread or a finite frequency spread is present. Numerical calculations indicate that quasi-antiparallel propagation dominates the EMIC event on 20 November 2015, which is consistent with the FFT spectral analysis results. We also find that obtained wave vectors, roughly agreeing with the validity of cold plasma theory, might significantly vary from wave packet to wave packet. Moreover, minimum resonant electron energies gradually increase from 0.5 MeV to tens of MeV with a decreasing parallel componet of k. Current results provide evidence that EMIC waves can be in resonance with the electrons of energies down to hundreds of keV. It further demonstrates that EMIC waves in a narrow frequency band can effectively interact with the relativistic electrons with a broad energy range.