7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

In-situ observations of plasma/particle distribution function and plasma waves
by the Arase satellite

Y. Miyoshi1, K. Asamura2, Y. Kazama3, S. Saito4, S. Kurita5, S. Matsuda6, Y. Katoh7, S. Imajo5, M.
Shoji1, T. Hori1, C.-W. Jun1, S. Nakamura1, S.-Y. Wang3, S. Kasahara7, S. Yokota8, T. Mitani2 , N.
Higashio2, Y. Kasahara6, H. Kojima5, A. Matsuoka5, I. Shinohara2
1
ISEE, Nagoya University, Japan
2JAXA, Japan
3Academia Sinica, Taiwan
4NICT, Japan
5Kyoto University, Japan
6
Kanazawa University, Japan
7Tohoku University, Japane-mail (speaker): miyoshi@isee.nagoya-u.ac.jp
In geospace, plasma/particle distributions exist in awide energy range from eV to several MeV, andelectromagnetic disturbances triggered by severe
variations in the solar surface, called space storms, cancause intense and prolonged aurora activities, a build-upof ring current, and other large scales variations. During
space storms, MeV electrons in the radiation belt showdisappearance and enhancement of their flux, indicatingthat acceleration processes to generate relativistic
electrons work associated with space storms. Geospace isa collisionless plasma system, and wave-particle
interactions play an important role in plasma/particle
dynamics.
To understand how wave-particle interactions in
geospace change the geospace plasma environment, howspace storms develop, and how energetic electrons in theradiation belts change, the Geospace Exploration
Satellite "Arase" was launched in 2016 and has operated
since 2017 to present [1][2]. The satellite has instrumentsfor observation of electrons (~ tens eV to ~ MeV) andions (10 eV/q -180 keV/q) with mass discrimination. The
satellite also observes electromagnetic waves (electricfield: DC-10MHz, magnetic field: DC-100kHz).
In this presentation, we will introduce the highlights inthe scientific achievements of the Arase satellite,
focusing on significant variations of the distributionfunction of plasma/particles. 1) direct detection ofelectron acceleration and scattering by whistler mode
waves, 2) scattering and heating of background ions byelectromagnetic ion cyclotron waves and ion Bernstein
waves, and mode conversion between waves. About 1),
we will discuss wave-particle interactions that produce
various electron dynamics, including electron
acceleration due to the interaction of electrons with achorus of nonlinear whistler mode waves, electron
scattering, and the correspondence with auroral emission
caused by electron scattering [3][4][5][6]. About 2), wewill discuss the mode conversion process between ion
Bernstein waves and electromagnetic ion cyclotron
waves through cross-energy couplings and a possible
role on the ion heating. Results about the direct
measurements of the phase differences between gyrating
ions and electromagnetic waves are presented [7][8].
References[1] Y. Miyoshi, Earth, Planet, Space, 70, 101 (2018)[2] Y. Miyoshi, Space Sci. Rev., 218, 38 (2022)[3] S. Kasahara et al., Nature, 554 (2018)[4] S. Kurita et al., Geophys. Res. Lett., 45 (2018)[5] Y. Kazama et al., Geophys. Res. Lett., 48 (2021)[6] S. Saito et al., J. Geophys. Res., 126 (2021)[7] M. Shoji et al., Sci. Rep., 11, 13480 (2021)[8] K. Asamura et al., Phys. Rev. Lett., 127, 245101(2021)