| Project/Area Number |
07640585
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Space and upper atmospheric physics
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| Research Institution | The University of Tokyo |
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Principal Investigator |
IWAGAMI Naomoto (1996-1997) The University of Tokyo, Graduate school, Faculty of Science, associate professor, 大学院・理学系研究科, 助教授 (30143374)
平原 聖文 (1995) 東京大学, 大学院・理学系研究科, 助手 (50242102)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Masato The University of Tokyo, Graduate school, Faculty of Science, associate professo, 大学院・理学系研究科, 助教授 (20227937)
HAYASHI Kanji The University of Tokyo, Graduate School, Faculty of Science, associate professo, 大学院・理学系研究科, 助教授 (60011730)
岩上 直幹 東京大学, 大学院・理学系研究科, 助教授 (30143374)
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| Project Period (FY) |
1995 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1997: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1996: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1995: ¥900,000 (Direct Cost: ¥900,000)
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| Keywords | extreme ultra violet light / oxygen ion / imaging / 磁気圏プラズマ / 電離圏イオン / 太陽風プラズマ / イオン組成 / 磁気圏イオン密度・速度分布 / 太陽光共鳴散乱 / 衛星観測 / プラズマダイナミックス |
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| Research Abstract |
We studied the possibility to image the oxygen ions which exist in the Earth's magnetotail. As we had had no knowledge of the existence of the oxygen ions in the tail region of the Earth's magnetosphere until several years before, the GEOTAIL spacecraft, which serches for the magnetosphere, identified the oxygen ions with very low temperature and high density. These oxygen ions flow as a beam from the Earth to the tail direction, whose velocity becomes higher as more distant. We will make big progress in studying the dynamics of the magnetosphere, if we can take picutres of the whole magnetosphere by using oxygen ions. The wavelength of the resonant scattering light is subject to the Doppler shifting, as the oxygen ions move relatively to the Sun. The efficiency of the resonant scatter becomes worse when ions are largely Doppler shifted because the width of the resonant scattering lines is several tens of milli-angstrom and the emission line width of the sun light is the same order to
… More
this. Resonant scatter does not occur essentially to the single emission line as helium, when relative velocity becomes over 50km/sec. Oxygen ions, on the other hand, have three resonant scattering lines which are very close to each other. There are 9 emission lines corresponding to the (singly and doubly ionized) oxygen ion in the solar light, so Oxygen ions can scatter another emission line resonantly when they are subjected to the Doppler shifting by the relative motion. We calculated the geometric factor which show the efficiency of the resonant scatter considering this effect. Also, we simulated the intensity of the scattered light from the tail region of the magnetosphere by the oxygen ions by using the model of the velocity, temperature and density of the oxygen ions from the results of the GEOTAIL spacecraft. Using these values, we concluded that the intensity of the light is 0.1-10 Rayleigh. The result means that we can image the Earth's magnetosphere with the resolution of 1 Re (Earth's radius) by using 25 cm diameter telescope, exposing about 10 minutes. Thus our study show the imaging of the magnetotail is possible in principle. Less
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