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

能量、动量和粒子从太阳风传输到地球磁层。这会导致磁层中高能粒子的整体和局部变化。在这项研究中，我们试图通过分析地面和卫星数据来了解磁层内部高能粒子的加速和消失机制。此外，我们还研究了太阳风中高能粒子的起源。(1)为了了解风暴期间内磁层中高能粒子数量减少的原因，我们利用SAMPEX卫星获取的1 MeV电子数据，对降水电子的突然增加(爆发)进行了统计研究。这种现象不依赖于当地时间和磁活动水平，但它的时间行为取决于这两个参数。特别是在上午区，发现了具有非常快(&lt；1秒)变化的爆发，即微暴。这些微暴的特征表明，在磁暴恢复阶段，电子降水与伴生亚暴的和声波相互作用而增强。(2)分析了1998年8月18日发生的两次X级太阳耀斑。研究发现，在14keV到93keV的能量范围内，脚点源的硬X射线谱呈单一的幂函数形状，这意味着脚点源是由非热电子产生的。另一方面，环顶上方源的硬X射线谱比脚点源的软，在50keV以上的能量范围内变得陡峭。这些结果为我们提供了一把钥匙，解决了电子在太阳耀斑中被加速到脚点的问题。

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.