1997 Fiscal Year Annual Research Report

地球周辺宇宙空間における無衝突プラズマ境界層の物理

Research Project

Project/Area Number	07304038
Research Institution	The Institute of Space and Astronautical Science (ISAS)
Principal Investigator	向井利典宇宙科学研究所, 太陽系プラズマ研究系, 教授 (60013695)
Co-Investigator(Kenkyū-buntansha)	國分征名古屋大学, 太陽地球環境研究所, 教授 (00011502) 松本紘京都大学, 超高層電波研究センター, 教授 (00026139) 寺沢敏夫東京大学, 大学院・理学研究科, 教授 (30134662) 森岡昭東北大学, 理学部, 教授 (50004479) 町田忍京都大学, 理学部, 助教授 (70209469)
Keywords	磁気圏境界層 / プラズマシート境界面 / 磁気リコネクション / 衝撃波 / サブストーム / 磁気圏尾部 / 低緯度境界原 / プラズマシート
Research Abstract	これまでと同様に、大小の観測データ検討会・研究会を開いて、GEOTAIL観測結果および理論・シミュレーション結果に基づいて磁気圏前面および尾部の磁気圏境界面、前面の衝撃波、プラズマシート境界層で生起している物理過程の研究が進められてきた。特に平成10年度は、本基盤研究の最終年度として論文のとりまとめ作業に比重が置かれた。その詳細は別に出版される報告書を参照していただくとして、本基盤研究によって得られた成果を代表的にまとめると以下のようになる。 1.磁気リコネクション過程が磁気圏境界層やプラズマシート境界層の形成、境界層を通してのエネルギー・運動量・粒子の輸送機構、および磁気圏全体のダイナミックス、磁気圏嵐におけるエネルギー開放過程に重要な役割を果たしている観測事実が次々と発見された。特に、粒子の3次元速度分布関数の高時間分解能の観測結果が粒子コード(Hybrid code、およびFull Particle Code)の計算機シミュレーションで再現できるようになり、従来のMHD的描像を超えて、粒子の輸送、加熱、加速の物理過程の研究の進展を大きく促した。 2.一方、近尾部プラズマシートでは、必ずしも磁気リコネクションだけでは説明できない低温・高密度のプラズマの存在が発見された。特に、これはIMFが北向きのときに顕著で、磁気圏境界面を通した粘性的な拡散過程も重要であることを示唆するものであるが、問題は、単に境界面だけでなく尾部中央付近のプラズマシートの領域においてさえ低温・高密度プラズマの存在が発見されたことである。一般的に、プラズマシートの密度は上流の太陽風密度と良い相関関係を示し、その起源を太陽風に求める根拠とされ、磁気リコネクションはその有力な素過程と考えられるが、両者の密度比はIMFが北向きのときの方が高いこと(すなわち、低温・高密度プラズマシートの存在)は驚きであった。すなわち、物質輸送に関しては粘性的拡散過程の寄与の方が大きいことを示唆しているものである。

Research Products
(20 results)

All Other

All Publications (20 results)

[Publications] M.Fujimoto, et al.: "A GEOTAIL observation of low-latitude boundary layer" Advances in Space Research. 20. 813-822 (1997)
[Publications] M.Fujimoto, et al.: "Dayside reconnection field lines in the south-dusk near-tail flank during an IMF By>0 dominated period" Geophysical Research Letters. 24. 931-934 (1997)
[Publications] M.Fujimoto, et al.: "Observations of earthward streaming electrons at the trailing boundary of a plasmoid" Geophysical Research Letters. 24. 2893-2896 (1997)
[Publications] M.Hoshino, et al.: "Origin of Hot and High Speed Plasmas in Plasma Sheet:Plasma Accerelation and Heating due to Slow Shocks" Advances in Space Research. 20. 973-982 (1997)
[Publications] H.Kojima, et al.: "GEOTAIL waveform observations of broadband/narrowband electrostatic noise in the distant tail" Journal of Geophysical Research. 102. 14439-14455 (1997)
[Publications] K.Maezawa, et al.: "Structure of the distant magnetotail and its dependence on the IMF By Component:GEOTAIL observations" Advances in Space Research. 20. 949-959 (1997)
[Publications] R.Nakamura, et al.: "Changes in the distant tail configuration during geomagnetic storms" Journal of Geophysical Research. 102. 9587-9601 (1997)
[Publications] A.Nishida, et al.: "The GEOTAIL mission:Principal characteristics and scientific results" Advances in Space Research. 20. 539-548 (1997)
[Publications] A.Nishida, et al.: "Response of the near-Earth magnetotail to a northward turning of the IMF" Geophysical Research Letters. 24. 943-946 (1997)
[Publications] S.M.Petrinec, et al.: "GEOTAIL observations of magnetosheath flow near the magnetopause,using WIND as a solar wind monitor" Journal of Geophysical Research. 102. 26943-26959 (1997)
[Publications] H.Shirai, et al.: "Mono-energetic ion drop-off in the inner magnetosphere" Journal of Geophysical Research. 102. 19873-19881 (1997)
[Publications] T.Terasawa, et al.: "Solar wind control of density and temperature in the near-Earth plasma sheet:WIND-GEOTAIL collaboration" Geophysical Research Letters. 24. 935-938 (1997)
[Publications] H.Matsumoto, et al.: "Plasma waves in the upstream and bow shock regions observed by GEOTAIL" Advances in Space Research. 20. 683-693 (1997)
[Publications] H.Matsumoto, et al.: "Intense bursts of electron cyclotron harmonic waves observed at the dayside magnetopause with GEOTAIL spacecraft" Geophysical Research Letters. 24. 49-52 (1997)
[Publications] T.Mukai, et al.: "IACG campaign-1 summary report:Initial results" Advances in Space Research. 20. 939-948 (1997)
[Publications] T.Nagai, et al.: "Substorms,tail flows,and plasmoids" Advances in Space Research. 20. 961-971 (1997)
[Publications] T.Nagai, et al.: "Plasma sheet pressure changes during the substorm growth phase" Geophysical Research Letters. 24. 963-966 (1997)
[Publications] M.Nakamura, et al.: "GEOTAIL observation at the dayside magnetopause confirmation of reconnection events" Advances in Space Research. 20. 767-776 (1997)
[Publications] T.Terasawa, et al.: "Particle acceleration at the interplanetary shock ahead of a large magneticcloud on October 18.1995:GEOTAIL-WIND collaboration" Advances in Space Research. 20. 641-644 (1997)
[Publications] J.-N.Tu, et al.: "Geotail observations of ion velocity distributions with multi-beam structures in the post-plasmoid current sheet" Geophysical Research Letters. 24. 2247-2250 (1997)

1997 Fiscal Year Annual Research Report

地球周辺宇宙空間における無衝突プラズマ境界層の物理

Principal Investigator

向井 利典 宇宙科学研究所, 太陽系プラズマ研究系, 教授 (60013695)

Research Products

[Publications] M.Fujimoto, et al.: "A GEOTAIL observation of low-latitude boundary layer" Advances in Space Research. 20. 813-822 (1997)

[Publications] M.Fujimoto, et al.: "Dayside reconnection field lines in the south-dusk near-tail flank during an IMF By>0 dominated period" Geophysical Research Letters. 24. 931-934 (1997)

[Publications] M.Fujimoto, et al.: "Observations of earthward streaming electrons at the trailing boundary of a plasmoid" Geophysical Research Letters. 24. 2893-2896 (1997)

[Publications] M.Hoshino, et al.: "Origin of Hot and High Speed Plasmas in Plasma Sheet:Plasma Accerelation and Heating due to Slow Shocks" Advances in Space Research. 20. 973-982 (1997)

[Publications] H.Kojima, et al.: "GEOTAIL waveform observations of broadband/narrowband electrostatic noise in the distant tail" Journal of Geophysical Research. 102. 14439-14455 (1997)

[Publications] K.Maezawa, et al.: "Structure of the distant magnetotail and its dependence on the IMF By Component:GEOTAIL observations" Advances in Space Research. 20. 949-959 (1997)

[Publications] R.Nakamura, et al.: "Changes in the distant tail configuration during geomagnetic storms" Journal of Geophysical Research. 102. 9587-9601 (1997)

[Publications] A.Nishida, et al.: "The GEOTAIL mission:Principal characteristics and scientific results" Advances in Space Research. 20. 539-548 (1997)

[Publications] A.Nishida, et al.: "Response of the near-Earth magnetotail to a northward turning of the IMF" Geophysical Research Letters. 24. 943-946 (1997)

[Publications] S.M.Petrinec, et al.: "GEOTAIL observations of magnetosheath flow near the magnetopause,using WIND as a solar wind monitor" Journal of Geophysical Research. 102. 26943-26959 (1997)

[Publications] H.Shirai, et al.: "Mono-energetic ion drop-off in the inner magnetosphere" Journal of Geophysical Research. 102. 19873-19881 (1997)

[Publications] T.Terasawa, et al.: "Solar wind control of density and temperature in the near-Earth plasma sheet:WIND-GEOTAIL collaboration" Geophysical Research Letters. 24. 935-938 (1997)

[Publications] H.Matsumoto, et al.: "Plasma waves in the upstream and bow shock regions observed by GEOTAIL" Advances in Space Research. 20. 683-693 (1997)

[Publications] H.Matsumoto, et al.: "Intense bursts of electron cyclotron harmonic waves observed at the dayside magnetopause with GEOTAIL spacecraft" Geophysical Research Letters. 24. 49-52 (1997)

[Publications] T.Mukai, et al.: "IACG campaign-1 summary report:Initial results" Advances in Space Research. 20. 939-948 (1997)

[Publications] T.Nagai, et al.: "Substorms,tail flows,and plasmoids" Advances in Space Research. 20. 961-971 (1997)

[Publications] T.Nagai, et al.: "Plasma sheet pressure changes during the substorm growth phase" Geophysical Research Letters. 24. 963-966 (1997)

[Publications] M.Nakamura, et al.: "GEOTAIL observation at the dayside magnetopause confirmation of reconnection events" Advances in Space Research. 20. 767-776 (1997)

[Publications] T.Terasawa, et al.: "Particle acceleration at the interplanetary shock ahead of a large magneticcloud on October 18.1995:GEOTAIL-WIND collaboration" Advances in Space Research. 20. 641-644 (1997)

[Publications] J.-N.Tu, et al.: "Geotail observations of ion velocity distributions with multi-beam structures in the post-plasmoid current sheet" Geophysical Research Letters. 24. 2247-2250 (1997)

向井利典宇宙科学研究所, 太陽系プラズマ研究系, 教授 (60013695)