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

在磁层亚风暴的生长阶段，地球的磁尾形成了薄层电流。在触发次暴扩展阶段中，流片的稳定性或缺乏稳定性可能起着重要作用。该项目将利用分析理论、霍尔磁流体动力学（Hall- mhd）模拟和粒子池（PIC）模拟来研究薄电流片的稳定性。理论和模拟结果将与星团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一个3D Hall MHD代码，该代码包含自适应网格细化，以及一个全电磁PIC代码。建议的任务是：(1)对比研究了Hall MHD和PIC模型中动力学漂移-气球不稳定性的线性稳定性，包括剪切流的影响和电离层系线的影响；(2)研究了漂移-气球不稳定性的非线性稳定性和可能的近爆炸性增长，以及亚暴发生时可能与重连动力学的耦合；（iii）理论和模拟预测与CLUSTER和POLAR在中尾和近地距离的观测结果的比较。拟议的工作整合了从高中到博士后研究的各个层次的教学和研究。它包括：(i)参加新罕布什尔大学的一个名为SMART项目（通过研究训练取得科学和数学成就）的暑期研究所，为当地高中生提供令人兴奋的研究经验；（ii）共同赞助研究与发现（RAD）项目的试点暑期实习，为大三和大四的本科生提供服务；（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.