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

磁层是非常动态的。磁层亚暴每隔几小时发生一次。从地球上看，它们就像极光一样可见。在空间中，与磁层亚暴相关的主要现象之一是双极化锋的产生。这是从磁尾向地球传播的、与等离子体片垂直的磁场分量的迅速增加。它们被称为双极化锋（df），因为磁场呈现出更像“偶极子”的结构。对df最常见的解释是它们与磁重联有关。这项工作与其他关于电流片的研究有关，如行星磁层、太阳日冕和太阳风的研究。本文的目标是研究实际尾模型中df的形成。该团队建议构建类似于亚暴生长阶段观察到的自一致二维电流片平衡的新类别。他们将利用动力学理论和具有真实电子离子质量比的二维粒子池（PIC）模拟来研究它们的重联稳定性。这将扩展到3D PIC模拟，以研究尾部等离子体响应的整个频谱，包括撕裂，气球/交换和拍打运动。将动力学图像与全球磁流体动力学模型的图像进行比较，目的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.