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，形成了等离子体层。这项研究的重点是回答为什么等离子体层电子会以它们的方式被观察到，以及它们来自哪里。该团队将开发一个基于数据的模型（包括经验关系），以研究近地等离子体片中的多个电子种群特征。一名女性首席研究员将领导这个项目，扩大代表性不足群体的参与。博士后的大量参与将促进早期职业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，并通过课堂演示、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的互校准THEMIS ESA和SST数据，确定近地等离子体层（6- 12re）中多个电子种群的来源及其在形成特定形状的电子分布函数中的作用。不同温度的多个电子居群可能表示不同的来源，例如地幔粒子从远尾进入，磁鞘粒子从侧磁层顶进入，电离层流出。不同的种群具有不同的各向异性。当已知电子居群的来源时，它们的建模变得更容易实现。作为研究的成果，将开发一个基于数据的模型（包括经验关系），该模型以太阳风、IMF参数、地磁活动指数和电离层参数（如极帽势）为参数，描述近地等离子体片（矩和通量）中的多个电子分布特征。获得近地等离子体层中电子居群的详细图像是重要的，并且具有很高的科学优先级。对THEMIS宇宙飞船提供的近地等离子体层地球静止距离外电子数据的详细分析是一项独特的研究，同时也是对正在进行的其他数据研究的补充，例如范艾伦探测器的数据。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.