1. HOME
  2. メンバー
  3. 山本 和弘

メンバー

山本 和弘

D2 山本 和弘 Yamamoto, Kazuhiro

E-mail: kazuhiro

地球の内部磁気圏(地球半径の6倍くらいまでの間の、地球の作る磁場に満たされた宇宙空間)で起こる、磁気流体波動やプラズマ波動の研究を行っています。
普段我々が感じている気象や海洋の現象(風、雨、嵐、さざ波)のように、宇宙空間では太陽からの風が吹いたり、荷電粒子が地球大気に降ってきたり、磁気嵐が起こったりします。

私の研究している波動については、あたかもサーフィンをするかのように荷電粒子が「波に乗って加速する」メカニズムが注目を集めています。

My major is space environment around the earth. I suppose that you know there are many many stars, planets, and satellites in space, but what do you think there are among them, for example, between the earth and the moon? Do you think there is nothing? The answers are the electric field, the magnetic field, and tenuous ionized gases. (The gravitational field is important for the theory of general relativity; however, it is out of my scope.) In a macroscopic viewpoint, the ionized gas, so-called plasma, acts as fluid coupling with the electromagnetic fields. There are waves and winds of plamsa in the space near the earth, like in the sea or the atmosphere of the earth.

 

I am interested in the wave-particle interaction between magnetohydrodynamic (MHD) waves and energetic charged particles. Similar to surfing, some particles can be accelerated by the electric field that is induced by the waves if they satisfy the resonance condition (drift/drift-bounce resonance). As a result, the resonant particles are transported earthward or anti-earthward. Because the energetic charged particles drive the ring current, which surrounds the earth, it is possible that the wave-particle interaction affects the current intensity, magnetic field variation on the ground, and energy dynamics in the near-earth space environment.

論 文

(主著)MAIN

[1] Yamamoto, K., Nosé, M., Mashiko, N., Morinaga, K., & Nagamachi, S. (2016). Estimation of magnetospheric plasma ion composition for 1956–1975 by using high time resolution geomagnetic field data created from analog magnetograms. Journal of Geophysical Research: Space Physics, 121(6), 5203-5212.

[2] Yamamoto, K., Nosé, M., Kasahara, S., Yokota, S., Keika, K., Matsuoka, A., et al. (2018). Giant pulsations excited by a steep earthward gradient of proton phase space density: Arase observation. Geophysical Research Letters, 45. https://doi.org/10.1029/2018GL078293.

(共著)JOINT

[1] Yokota, S., Kasahara, S., Mitani, T., Asamura, K., Hirahara, M., Takashima, T., ... & Shibano, Y. (2017). Medium-energy particle experiments–ion mass analyzer (MEP-i) onboard ERG (Arase). Earth, Planets and Space, 69(1), 172.

[2] Oimatsu, S., Nosé, M., Takahashi, K., Yamamoto, K., Keika, K., Kletzing, C. A., et al. (2018). Van Allen Probes observations of drift‐bounce resonance and energy transfer between energetic ring current protons and poloidal Pc4 wave. Journal of Geophysical Research: Space Physics, 123, 3421–3435. https://doi.org/10.1029/2017JA025087.

[3] Oimatsu, S., Nosé, M., Teramoto, M., Yamamoto, K., Matsuoka, A., Kasahara, S., et al. (2018). Drift‐bounce resonance between Pc5 pulsations and ions at multiple energies in the nightside magnetosphere: Arase and MMS observations. Geophysical Research Letters, 45. https://doi.org/10.1029/2018GL078961.

[4] Nosé, M., Matsuoka, A., Kasahara, S., Yokota, S., Teramoto, M., Keika, K., et al (2018). Magnetic field dipolarization and its associated ion flux variations in the dawn side deep inner magnetosphere: Arase observations. Geophysical Research Letters, 45. https://doi.org/10.1029/2018GL078825.

今年の目標

時間と締め切りを守ろう。

見直しをちゃんとしよう。