GEM: Dipolarization and Particle Acceleration at Substorm Onset

该项目将结合三维磁流体动力学（MHD）和测试粒子（离子和电子）模拟来研究磁亚暴期间粒子的能量。亚暴发生在磁尾的特征是突然的“双极化”，也就是说，从一个伸展的尾巴状磁场返回到一个更偶极的磁场，也被解释为“电流中断”。这种重构与强烈的感应电场有关，这种感应电场在空间和时间上都有很强的局域性。该项目将研究各种起始特征（如磁重联、双极化和粒子加速）与高能粒子通量的时空特性之间的关系。MHD/测试颗粒模拟将辅以动态颗粒池（PIC）模拟和数据分析。将用于与模拟结果进行比较的数据将来自洛斯阿拉莫斯地球同步卫星和美国宇航局THEMIS任务。磁亚暴活动是一种普遍的等离子体和磁场过程的特殊表现，它涉及到磁场中能量的储存和能量的突然释放，并通过磁重联及其后果将其转化为粒子能量。了解粒子加速到高能量的机制是理解和预测空间天气的基本要素，也是理解太阳和天体物理爆发等离子体/磁场过程的基本要素。

This project will use a combination of 3-dimensional magnetohydrodynamic (MHD) and test particle (ions and electrons) simulations to investigate the energization of particles during the unset of a magnetic substorm. Substorm onset in the magnetotail is characterized by a sudden "dipolarization," that is, return from a stretched tail-like to a more dipolar magnetic field, also interpreted as "current disruption." This reconfiguration is associated with a strong induced electric field, which is strongly localized in space as well as in time. The project will examine the relationship between various onset signatures, such as magnetic reconnection, dipolarization, and particle acceleration, and the spatial and temporal properties of energetic particle fluxes. The MHD/test particle simulations will be supplemented by kinetic particle-in-cell (PIC) simulations as well as data analyses. The data that will be used for comparisons with the simulation results will come from the Los Alamos geosynchronous satellites and from the NASA THEMIS mission.Magnetic substorm activity is a special manifestation of a universal plasma and field process, which involves energy storage in magnetic fields and the sudden release of this energy and its conversion to particle energy via magnetic reconnection and its consequences. Understanding the mechanisms by which particles are accelerated to high energies is an essential element of understanding and predicting space weather, as well as for understanding solar and astrophysical eruptive plasma/magnetic field processes.