Stability of Thin Current Sheets in the Earth's Magnetotail: Theory, Simulations, and Observations

在磁层亚暴的发展阶段，地球磁尾中形成了薄薄的电流片。当前冰盖的稳定性或缺乏可能在触发亚暴扩展阶段中起着重要作用。本项目将利用解析理论、霍尔磁流体(Hall-MHD)模拟和单胞粒子(PIC)模拟来研究薄电流片的稳定性。理论和模拟结果将与集群和极地卫星的观测结果进行比较。将使用的高性能计算工具包括结合自适应网格优化的3D Hall MHD代码和完全电磁的PIC代码。建议的任务是：(1)比较研究霍尔MHD和PIC模型中漂移-气球动力学不稳定性的线性稳定性，包括切变流动的影响和电离层的搭线效应；(2)研究漂移-气球不稳定性的非线性稳定性和可能的近爆炸性增长，以及在亚暴开始时可能与重联动力学的耦合；(3)将理论和模拟的预测与中尾和近地距离的星系团和极地观测进行比较。拟议的工作整合了从高中到博士后学习的所有层面的教学和研究。它包括：(I)参加新汉普郡大学一个名为SMART(通过研究培训实现科学和数学成就)的暑期学院，该项目为当地高中生提供令人兴奋的研究体验；(Ii)共同赞助为本科生在研究和发现(RAD)计划中进行的试点暑期实习；以及(Iii)指导博士后和初级研究科学家。

Thin sheets of electric current form in the Earth's magnetotail during the growth phase of a magnetospheric substorm. It is likely that the stability or lack thereof of the current sheets plays an important role in the triggering of the substorm expansion phase. This project will utilize analytical theory, Hall Magnetohydrodynamic (Hall-MHD) simulations and Particle-In-Cell (PIC) simulations to study the stability of thin current sheets. The theoretical and simulation results will be compared with observations from the Cluster and Polar satellites. The high-performance computing tools to be used include a 3D Hall MHD code which incorporates Adaptive Mesh Refinement, and a fully electromagnetic PIC code. The tasks proposed are: (i) a comparative study of the linear stability of the kinetic drift-ballooning instability in Hall MHD and PIC models, including the effect of sheared flows and the effects of line-tying at the ionosphere, (ii) investigation of the nonlinear stability and possible near-explosive growth of drift-ballooning instabilities and possible coupling to reconnection dynamics at substorm onset, and (iii) the comparison of the predictions of theory and simulations with CLUSTER and POLAR observations at mid-tail and near-Earth distances. The proposed work integrates teaching and research at all levels, from high-school to postdoctoral studies. It includes: (i) participation in a summer institute at the University of New Hampshire called Project SMART (Science and Mathematics Achievement through Research Training) which provides exciting research experiences for local high school students, (ii) co-sponsorship of a pilot Summer Internship in the Research And Discover (RAD) program for undergraduates in their junior and senior years, and (iii) mentorship of postdoctoral and junior research scientists.