GEM: Source of Energetic Ions in the Cusp and Minor Ion Transfer Across the Magnetopause

从太阳风到磁层的质量、动量和能量的传递是磁层物理学中的一个重要问题。本研究的第一阶段将集中于磁层界长期以来关于在磁层尖端观测到的高能离子源区域的争论。一种可能是离子在尖端处局部加速。另一种可能性是离子在弓形激波处被加速并被输送到尖端。为了研究这个问题，环绕磁层顶的行星际磁力线（IMF）将追溯到弓形激波，以确定这些磁力线是否与准平行激波区域相连。准平行激波是高能离子的一个众所周知的来源。一些完全覆盖在磁层顶周围的磁力线将与地磁力线重新连接，并允许磁鞘和弓形激波加速离子进入尖端区域。在Polar/TIMAS、CAMMICE数据中，尖峰高能粒子（CEP）事件的发生将与这些覆盖的场线与准平行弓形激波区的连接有关。当IMF磁场线穿过磁鞘走向磁层顶时，为了考虑与准平行弓形激波区域的所有可能联系，这些弓形激波拦截点的路径也将沿着弓形激波进行追踪。与准平行激波的任何连接都将使激波中的高能离子在IMF场线上，这些场线上随后与地磁力线相连。用于确定弓形激波准平行激波区域的位置以及覆盖在磁层顶周围的IMF磁场线与弓形激波的连接位置的软件工具将作为交互式网络工具向公众提供。第二阶段将重点研究太阳风离子从磁鞘到低纬度边界层（LLBL）的He2+/H+密度比降低了40%。在尖端的高能离子中也观察到了类似的结果，这表明了一个依赖于质量的进入过程。由极地/TIMAS仪器在尖端测量的密度比将与由wind /3DP测量提供的太阳风密度比进行比较，以记录小离子在磁层顶的转移比。

The understanding of the transfer of mass, momentum, and energy from the solar wind into the magnetosphere is an important problem in magnetospheric physics. The first phase of this study will focus on a long standing debate within the magnetospheric community concerning the source region of energetic ions observed in the magnetospheric cusp. One possibility is that the ions are locally accelerated in the cusp. The alternate possibility is that the ions are accelerated at the bow shock and transported into the cusp. To investigate this issue, interplanetary magnetic field lines (IMF) draped around the magnetopause will be traced back to the bow shock to establish whether or not those field lines connect to the quasi-parallel shock region. The quasi-parallel shock is a well known source for energetic ions. Some of these fully draped field lines around the magnetopause will reconnect with geomagnetic field lines and allow magnetosheath and bow shock accelerated ions to enter the cusp region. The occurrence of cusp energetic particles (CEP) events in Polar/TIMAS, CAMMICE data will be correlated with the connection of these draped field lines to the quasi-parallel bow shock region. To consider all possible connections with the quasi-parallel bow shock regions while the IMF field lines cross the magnetosheath towards the magnetopause, the path of these bow shock interception points will also be traced across the bow shock. Any connection with the quasi-parallel shock will cause energetic ions from the shock to be on IMF field lines which are subsequently connected to geomagnetic field lines. The software tools used to determine the location of the quasi-parallel shock region at the bow shock and where IMF field lines draped around the magnetopause connect to the bow shock will be made available to the public as interactive web tools.The second phase will focus on the fact that there is a 40% reduction of the He2+/H+ density ratio from the magnetosheath to the low-latitude boundary layer (LLBL) for solar wind ions. A similar result has been observed for energetic ions in the cusp, suggesting a mass dependent entry process. Density ratio measurements by the Polar/TIMAS instrument in the cusp will be compared with simultaneous observations of the density ratio in the solar wind provided by the Wind/3DP measurements to document the transfer ratio of minor ions across the magnetopause.