GEM: Particle Acceleration by Foreshock Transients

在整个宇宙中，冲击将粒子加速到相对论速度-在天体物理过程中，更局部地在地球附近的空间区域。冲击如何能将粒子加速到比它们自身的冲击势能储备更高的能量，这是一个谜。该项目将调查冲击进入磁层之前等离子体流的不规则性，研究等离子体气泡和热流异常。该项目的成果可直接应用于空间气象模型;因此，该项目涉及《国家空间气象行动计划》所列目标之一。该项目还将有助于了解整个宇宙的冲击加速度。三名早期职业研究人员和一名研究生将得到支助，主要目标是：确定上游电子束对高能粒子向内穿透造成的空间气象现象的作用;以及就费米型冲击加速过程的典型预加速需要提供新的见解。首次提供前震区域的高质量和高分辨率THEMIS和MMS数据。THEMIS提供大尺度磁结构沿着高频磁波动和超热粒子（25 keV）的数据，而MMS能够分辨小尺度（10-100 km）的高时间分辨率（30 - 150 ms），提供微尺度和电子动力学量。这些观测将得到Cluster和DMSP的补充，它们监测尖点中的高能粒子通量，并来自所有天空成像仪和NSF资助的SuperDARN数据，提供加速粒子的特征。综合这些观察结果是一项具有挑战性的任务。该提案利用经过良好测试的3D全球混合仿真代码来组织数据并实现预期结果。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估而被认为值得支持。

Shocks accelerate particles to relativistic speeds throughout the universe – in astrophysical processes and more locally in the region of space near the Earth. It is a mystery how shocks can accelerate particles to energies higher than their own shock potential energy reserve. This project will investigate irregularities in plasma flows ahead of shocks moving into the magnetosphere, studying plasma bubbles and hot flow anomalies. The results of this project have direct applications in space weather models; it thus addresses one of the goals set out in the National Space Weather Action Plan. The project will also help understand shock acceleration throughout the universe. Three early career researchers and a graduate student will receive support.The key objectives are (i) to determine the role of upstream electron energization on space weather phenomena that result from inward penetration of energetic particles; and (ii) to provide new insights in the classic pre-acceleration need for Fermi type shock acceleration processes. For the first time high quality and resolution THEMIS and MMS data from the foreshock region are available. THEMIS provides data on large scale magnetic structures along with high-frequency magnetic fluctuations and superthermal particles ( 25 keV), while MMS is capable of resolving small scale (10-100 km) high time resolution (30 -150 ms) providing microscale and electron dynamics quantities. The observations will be supplemented by Cluster and DMSP which monitor the energetic particle flux in the cusp and from all sky imagers and NSF-funded SuperDARN data providing signatures of accelerating particles. Combining these observations is a challenging task. The proposal utilizes a well-tested 3D global hybrid simulation code to organize the data and achieve the desired results.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.