GEM: Sources of Electron Populations in the Plasma Sheet

地球的磁尾区域充满了来自太阳风和地球电离层的带电粒子，形成了等离子体片。这项研究的重点是回答为什么观察到等离子体片电子的方式以及它们来自哪里。该团队将开发一个基于数据的近地等离子体片中多电子布居特征的模型(包括经验关系)。一名女性首席调查员将领导这一项目，扩大代表性不足群体的参与。博士后的大量参与将促进职业生涯早期劳动力的培训和学习机会。该项目的成果将被纳入密歇根大学现有的课程，并通过课堂演讲、科学会议和出版物进行传播。这项工作的主要目标是利用整个运行期间内校准的THEMIS、ESA和SST数据，确定近地等离子体片(6-12 RE)中多个电子布居的来源及其在形成特定形状的电子分布函数中的作用。具有不同温度的多个电子布居可能指示不同的来源，例如通过远尾部进入的地幔粒子和通过侧面磁层顶进入的磁鞘粒子、电离层流出。不同的种群可能具有不同的各向异性。当电子布居的来源已知时，对它们的建模变得更容易实现。作为调查的成果，将建立一个由太阳风、国际货币基金组织参数、地磁活动指数和电离层参数(例如，极冠电位)参数化的近地等离子体片中多电子布居特征(矩和通量)的基于数据的模型(包括经验关系)。获得近地等离子体片中电子总数的详细图像是重要的，具有高度的科学优先事项。对近地等离子体片中地球静止距离以外的THEMIS航天器提供的电子数据的详细分析是一项独特的调查，同时也是对正在进行的其他数据研究的补充，例如Van Allen Probe数据。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Earth's magnetotail region is filled with charged particles from the solar wind and the terrestrial ionosphere, forming the plasma sheet. The research focuses on answering why the plasma sheet electrons are observed in the way they are and where they come from. The team will develop a data-based model (including empirical relations) of multiple electron population characteristics in the near-Earth plasma sheet. A female principal investigator will lead this project, expanding participation among underrepresented groups. The heavy involvement of a postdoc will promote training and learning opportunities for the early-career workforce. Results from this project are intended to be incorporated into existing courses at the University of Michigan and disseminated via presentations in the classroom, scientific meetings, and publication. The primary objective of this effort is to define the sources of multiple electron populations in the near-Earth plasma sheet (6-12 RE) and their roles in forming specific shapes of electron distribution functions using inter-calibrated THEMIS ESA and SST data from the whole period of operation. Multiple electron populations with different temperatures may indicate the different sources, e.g., the mantle particles entering through the distant tail and the magnetosheath particles entering through the flank magnetopause, ionosphere outflow. Different populations can have different anisotropy. When the sources of electron populations are known, the modeling of them becomes more achievable. As a product of the investigation, a data-based model (including empirical relations) of multiple electron population characteristics in the near-Earth plasma sheet (moments and fluxes) parameterized by the solar wind, IMF parameters, geomagnetic activity indices, and ionosphere parameters (e.g., polar cap potential) will be developed. Obtaining a detailed picture of the electron population in the near-Earth plasma sheet is important and of high scientific priority. The detailed analysis of the electron data provided by THEMIS spacecraft outside the geostationary distances in the near-Earth plasma sheet is a unique investigation and, at the same time, complementary to the ongoing studies with other data, such as, for example, Van Allen Probes data.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.