Dynamics of high energy particles in the earth's inner magnetosphere

地球内部磁层中高能粒子的动力学

• 批准号: 10640429
• 负责人: MASUDA Satoshi
• 金额: $ 1.73万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640429/
• 关键词: radiation belt; magnetosphere; high energy particles; magnetic storm; solar flare; particle acceleration; サブストーム

Energy, momentum, and particles are transported from solar wind into the earth's magnetosphere. This causes global and local changes to high energy particles in the magnetosphere. In this study, we tried to understand the acceleration and disappearance mechanism of high energy particles in the inner magnetosphere, analyzing ground-based and satellite data. Also, we studied the origin of high energy particles in the solar wind.(1) In order to understand why the number of high energy particles decease in the inner magnetosphere during the storm time, we statistically studied sudden increase (burst) of precipitating electrons, using 1-MeV electron data taken with the SAMPEX satellite. This phenomenon is observed without any dependence on the local time and the magnetic activity level, but its temporal behavior depends on both parameters. Especially in the morning sector, it was found that bursts with a very fast (<1 sec) variation, i.e., micro-bursts, occur. The characteristics of these micro-bursts suggest that electron precipitation is enhanced by an interaction with chorus wave, accompanying substorms during the recovery phase of magnetic storm.(2) We analyzed two X-class solar flares that occurred on 18 August 1998. It was found that the hard X-ray spectrum of footpoint sources, seems a single power-law shape in the energy range from 14 to 93 keV.This means that footpoint sources are originated by non-thermal electrons. On the other hand, the hard X-ray spectrum of the above-the-looptop source is softer than that of footpoint sources, and it becomes steeper in the energy range above about 50 keV.These results give us a key to solve the question, where electrons, precipitating to footpoints, are accelerated in solar flares.

能量、动量和粒子从太阳风被输送到地球的磁层。这导致磁层中的高能粒子发生全球和局部变化。在这项研究中，我们试图了解内磁层高能粒子的加速和消失机制，分析地面和卫星数据。此外，我们还研究了太阳风中高能粒子的起源。(1)为了理解为什么在磁暴期间内磁层中高能粒子的数量减少，我们统计研究了沉淀电子的突然增加（爆发），使用SAMPEX卫星拍摄的1 MeV电子数据。这种现象的观测不依赖于当地时间和磁活动水平，但其时间行为取决于这两个参数。特别是在早晨扇区，发现具有非常快（<1秒）变化的突发，即，微爆发生。这些微暴的特征表明，在磁暴的恢复阶段，伴随着亚暴的合唱波的相互作用增强了电子沉淀。(2)我们分析了1998年8月18日发生的两次X级太阳耀斑。结果表明，在14 ~ 93 keV能量范围内，足点源的硬X射线谱呈单一的幂律形状，这表明足点源是由非热电子产生的。另一方面，硬X射线谱的上述的looptop源是软的比足点源，它变得陡峭的能量范围以上约50 keV。这些结果给我们一个关键，以解决这个问题，电子，沉淀到足点，加速在太阳耀斑。

项目成果

Y.Kamide: "Two-step development of geomagnetic storms"Journal of Geophysical Research. 103. 6917-6921 (1998)

Y.Kamide：“地磁暴的两步发展”地球物理研究杂志。

Nakamura,R.: "SAMPEX observations of storm-associated electron flux variations in the outer radiation belt." Journal of Geophysical Research. 103. 26261-26269 (1998)

Nakamura,R.：“SAMPEX 对外辐射带中与风暴相关的电子通量变化的观测。”

H.Nakai: "Substorm currents associated with magnetospheric dipolarization : Geotail observations"J.Geophys.Res.. 105. 18781-18792 (2000)

H.Nakai：“与磁层偶极化相关的亚暴流：Geotail 观测”J.Geophys.Res.. 105. 18781-18792 (2000)

R.Nakamura: "SAMPEX observations of storm-associated electron flux variations in the outer radiation belt"J.Geophys.Res.. 103. 26261-26269 (1998)

R.Nakamura：“外辐射带中与风暴相关的电子通量变化的 SAMPEX 观测”J.Geophys.Res.. 103. 26261-26269 (1998)

Y.Kamide: "Two-step development of geomagnetic storms"J.Geophys.Res.. 103. 6917-6921 (1998)

Y.Kamide：“地磁暴的两步发展”J.Geophys.Res.. 103. 6917-6921 (1998)