Three-Dimensional Dynamics of Thin Current Sheets and Their Role in the Triggering and Spatio-Temporal Evolution of Magnetotail Substorms

研究人员将对磁层亚暴成长阶段形成的薄电流片进行分析和高分辨率计算研究。这些电流片是在磁尾观测到的，可能在亚暴爆发中起着重要作用。前人的计算结果与多颗卫星观测的亚暴缓慢增长和脉冲式爆发前阶段薄电流层的时空特征有很好的定量一致性，并已确定压力驱动的气球不稳定是触发亚暴的一种潜在机制。这项研究将使用霍尔磁流体力学的理论框架，包括带有霍尔电流和电子压力梯度项的广义欧姆定律。任务包括发展更完整的重联理论、薄电流片和磁尾亚暴动力学，以及在有和没有速度切变的情况下压力驱动的气球不稳定性之间的动力学耦合。

The investigators will conduct analytical and high-resolution computational studies of thin current sheets which are formed during the growth phase of magnetospheric substorms. These current sheets are observed in the magnetotail and may play an important role in substorm onset. Previous calculations are in good quantitative accord with multi-satellite observations of the spatial and temporal characteristics of thin current sheets in the slow growth and impulsive pre-onset phases of substorms, and have led to the identification of the pressure-driven ballooning instability as a potential mechanism for substorm trigger. This investigation will use the theoretical framework of Hall magnetohydrodynamics, including a generalized Ohm's law with Hall current and electron pressure gradient terms. Tasks include the development of a more complete theory of reconnection, thin current sheet and magnetotail substorm dynamics, and dynamical coupling between pressure-driven ballooning instabilities with and without velocity shears.