GEM: Dipolarization Fronts and Reconnection Onset in Realistic Models of the Magnetotail

磁层是动态的。磁层亚暴每隔几个小时就会发生一次。从地球上看，它们就像极光一样可见。在空间，与磁层亚暴有关的主要现象之一是产生偶极锋。这些是垂直于等离子体片的磁场分量的快速增加，这些磁场分量从磁尾向地球传播。它们被称为偶极锋（DF），因为磁场呈现出更“类似偶极”的配置。 对磁场不稳定最常见的解释是它们与磁场重联有关。这项工作是相关的电流片，如在行星磁层，太阳日冕和太阳风的其他研究。本建议的目的是调查的形成DF在现实的尾巴模型。该团队建议构建新的自洽2D电流片平衡类类似于亚暴生长阶段观察到的。他们将通过使用动力学理论和具有真实电子与离子质量比的二维粒子模拟来研究它们的重联稳定性。这将被扩展到三维PIC模拟研究整个频谱的尾部等离子体响应，包括撕裂，气球/交换和扑动。动力学图片将与全球磁流体动力学模型进行比较，目标是将动力学物理纳入全球模型。应用物理实验室有一个暑期学生帮助研究的项目。

The magnetosphere is very dynamic. Magnetospheric substorms occur every few hours. Viewed from the Earth they are visible as auroral displays. In space one of the main phenomena associated with magnetospheric substorms is the generation of dipolarization fronts. These are rapid increases in the component of the magnetic field normal to the plasma sheet that propagate from the magnetotail toward the Earth. They are called dipolarization fronts (DFs) since the magnetic field assumes a more "dipole like" configuration. The most common explanation for DFs is that they are related to magnetic reconnection. This work is relevant to other studies of current sheets such as those in planetary magnetospheres, the solor corona and the solar wind. The goal of this proposal is to investigate the formation of DFs in realistic tail models. The team proposes to construct new classes of self-consistent 2D current sheet equilibria similar to those observed during the growth phase of substorms. They will investigate their stability to reconnection by using kinetic theory and 2D particle in cell (PIC) simulations with realistic electron to ion mass ratio. This will be extended to 3D PIC simulations to investigate the whole spectrum of tail plasma responses including tearing, ballooning/interchange and flapping motions. The kinetic picture will be compared with that from global magnetohydrodynamic models with the goal of including the kinetic physics in the global models. The Applied Physics Laboratory has a program for summer students to help with the research.