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

理解质量、动量和能量从太阳风到磁层的传输是磁层物理学中的一个重要问题。这项研究的第一阶段将侧重于磁层内部关于在磁层尖点观察到的高能离子的源区的长期辩论。一种可能性是离子在尖端局部加速。另一种可能性是离子在弓形激波中加速，并被输送到尖端。为了研究这个问题，覆盖在磁层顶周围的行星际磁力线(IMF)将被追溯到弓激波，以确定这些磁力线是否连接到准平行激波区。准平行激波是众所周知的高能离子的来源。磁层顶周围这些完全覆盖的场线中的一部分将与地磁场线重新连接，并允许磁鞘和弓形激波加速离子进入尖点区域。在Polar/TIMAS，CAMMICE资料中，尖端高能粒子(CEP)事件的发生将与这些覆盖的场线与准平行的弓形激波区的连接相关联。为了考虑当IMF场线穿过磁鞘朝向磁层顶时与准平行的弓激波区域的所有可能联系，这些弓激波截止点的路径也将被追踪跨越弓激波。与准平行激波的任何联系都将导致激波产生的高能离子位于IMF场线上，这些场线随后连接到地磁场线。用于确定弓激波处准平行激波区的位置以及覆盖在磁层顶周围的IMF场线连接到弓激波的位置的软件工具将作为交互式网络工具向公众提供。第二阶段将重点关注太阳风离子从磁鞘到低纬边界层(LLBL)的He2+/H+密度比减少40%的事实。对于尖端的高能离子也观察到了类似的结果，表明进入过程与质量有关。将把在尖点由Polar/TIMAS仪器测量的密度比与由Wind/3DP测量提供的太阳风中的密度比同时观测进行比较，以证明次要离子在磁层顶上的转移比。

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.