[P-EM11] Dynamics of the Inner Magnetospheric System

[PEM11-10] Statistical analyses on low energy ion heating by EMIC waves via wave-particle interaction analyses: Arase observations

*Masafumi Shoji¹, Yoshizumi Miyoshi¹, Lynn M Kistler^1,2, Kazushi Asamura³, Yasumasa Kasaba⁴, Ayako Matsuoka⁶, Yoshiya Kasahara⁵, Shoya Matsuda⁵, Fuminori Tsuchiya⁴, Atsushi Kumamoto⁴, Satoko Nakamura¹, Chae-Woo Jun¹, Iku Shinohara³ (1.Nagoya Univ., 2.Univ. New Hampshire, 3.ISAS/JAXA, 4.Tohoku Univ., 5.Kanazawa Univ., 6.Kyoto Univ.)

Keywords:ion heating, EMIC wave

Electromagnetic ion cyclotron (EMIC) waves are generated through the cyclotron wave-particle interaction, affecting the plasma environment in the magnetosphere. Heating of the ions by EMIC waves in the inner magnetosphere has also been investigated by spacecraft observations by comparing variations of ion distribution and waves. The energy transfer between the plasma waves and ions can be quantitatively evaluated by calculating the inner product between the wave electric field vector and the ion velocity vector, so-called WPIA (wave-particle interaction analysis). We adapt the WPIA method to the Arase spacecraft data and investigate the spatial distribution of the positive qV・E region in the inner magnetosphere. Using 2.5 years data, we choose EMIC wave events associating ion flux enhancement between 10 eV to 100 eV of which the WPIA analysis can be applied for the necessary data sets observed by the Arase satellite. The occurrence peaks of the proton and helium heating events appear in the dayside and post noon regions. We classify the enhancements of low energy ion flux by their formation mechanism. Most of the ion flux enhancements are generated through the ion heating by the EMIC waves while some others are formed by the sloshing motion of the ions. We also perform test particle simulations to understand the ion heating process in the perpendicular direction by the parallel propagating EMIC waves.