地球外辐射带中能量在100千电子伏特及以上的高能电子是引发灾害性空间天气事件的主要因素之一。地球磁暴期间外辐射带高能电子的通量及其边界变化剧烈，是空间物理研究的热点与前沿。Baker et al. [2014, Nature] 利用Van Allen Probes从2012年至2013年的观测，提出在地磁较为平静的时期，外辐射带内侧存在不可穿越的边界。然而，目前尚缺乏太阳风外部驱动和磁暴期间磁层内部扰动对外辐射带内边界影响的系统研究。本项目计划利用SAMPEX卫星、NOAA POES系列卫星和Van Allen Probes卫星自1993年以来的长期空间探测数据，从太阳风与行星际磁场条件（外因）和等离子体层顶位置、当地电磁场波动条件（内因）两方面综合分析暴时外辐射带内边界的变化，从而进一步研究造成内边界变化的因果链。本项目的实施将进一步增强人们对地球外辐射带高能电子动力学过程的认识。

The electrons with energies at and above 100 keV within the outer radiation belt are the main cause of hazardous space weather effects and malfunctions or even damages of the electronics onboard spacecrafts and artificial satellites. During geomagnetic storms, the boundaries and electron fluxes of the outer radiation belt vary dramatically. With the launches of space missions during recent years, and the frequently occurred space weather events, it has become a frontier the dynamic variation of the inner boundary of the outer radiation belt. Using the observations of Van Allen Probes from 2012 to 2013, Baker et al. [2014, Nature] suggested that during geomagnetically quiet periods, there is an impenetrable barrier to ultrarelativistic electrons in the outer radiation belt. However, it lacks systematic research on how solar wind and IMF, together with dynamic processes inside magnetosphere, affect the inner boundary during geomagnetic storms. In this work, based on the observations since 1993 of SAMPEX, NOAA POES and Van Allen Probes, the variations of the inner boundary are analyzed from the points of view of solar wind and IMF conditions (external causes) and locations of plasmapause and local electromagnetic wave fields (internal causes), respectively, so as to understand storm-time variations of the inner boundary in a cause-and-effect manner. This work will enhance the understanding on the dynamic processes of energetic electrons in Earth's outer radiation belt.