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生长阶段形成的薄电流片进行分析和高分辨率计算研究。这些电流片在磁尾中被观察到，可能在亚暴的发生中起重要作用。以往的计算结果与多颗卫星对亚暴缓慢增长和脉冲爆发前阶段薄电流片时空特征的观测结果在数量上很好地吻合，从而确定了压力驱动的气球不稳定性是亚暴触发的潜在机制。本研究将使用霍尔磁流体力学的理论框架，包括具有霍尔电流和电子压力梯度项的广义欧姆定律。任务包括开发更完整的重联理论，薄电流片和磁尾亚风暴动力学，以及有和没有速度剪切的压力驱动气球不稳定性之间的动态耦合。

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.