GEM: Particle Acceleration by Foreshock Transients

GEM：前震瞬变的粒子加速

• 批准号: 2210319
• 负责人: Zixu Liu
• 金额: $ 46.64万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-10-01 至 2024-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2210319&HistoricalAwards=false
• 关键词: GEM; Particle; Acceleration; Foreshock; Transients

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.

激波将粒子加速到整个宇宙的相对论速度--在天体物理过程中，更多的是在地球附近的空间区域。激波如何将粒子加速到高于其自身激波势能储备的能量，这是一个谜。这个项目将调查激波进入磁层之前的等离子体流动的不规则性，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式；因此，它解决了国家空间气象行动计划中规定的目标之一。该项目还将有助于理解整个宇宙的冲击波加速。三名早期职业研究人员和一名研究生将得到支持。主要目标是(I)确定上游电子能量在高能粒子向内穿透导致的空间天气现象中的作用；以及(Ii)对费米型冲击加速过程的经典加速前需求提供新的见解。首次获得了来自前震地区的高质量和高分辨率的THEMIS和MMS数据。THEMIS提供关于大尺度磁结构以及高频磁涨落和超热粒子(25keV)的数据，而MMS能够分辨小尺度(10-100公里)高时间分辨率(30-150毫秒)，提供微尺度和电子动力学参数。观测将得到星团和DMSP的补充，它们监测尖点和来自所有天空成像仪的高能粒子通量，以及由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全球混合模拟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智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Evidence of Electron Acceleration via Nonlinear Resonant Interactions with Whistler-mode Waves at Foreshock Transients

前震瞬态时通过与惠斯勒模式波的非线性共振相互作用实现电子加速的证据

• DOI: 10.3847/1538-4357/acd9ab
• 发表时间: 2023
• 期刊: The Astrophysical Journal
• 作者: Shi, Xiaofei;Artemyev, Anton;Angelopoulos, Vassilis;Liu, Terry;Zhang, Xiao-Jia
• 通讯作者: Zhang, Xiao-Jia

Intense Whistler-mode Waves at Foreshock Transients: Characteristics and Regimes of Wave−Particle Resonant Interaction

前震瞬变时的强惠斯勒模式波：波与粒子共振相互作用的特征和机制

• DOI: 10.3847/1538-4357/acb543
• 发表时间: 2023
• 期刊: The Astrophysical Journal
• 作者: Shi, Xiaofei;Liu, Terry;Artemyev, Anton;Angelopoulos, Vassilis;Zhang, Xiao-Jia;Turner, Drew L.
• 通讯作者: Turner, Drew L.

Foreshock Ion Motion Across Discontinuities: Formation of Foreshock Transients

• DOI: 10.1029/2022ja031161
• 发表时间: 2023-04
• 期刊: Journal of Geophysical Research: Space Physics
• 作者: T. Liu;V. Angelopoulos;A. Vu;Hui Zhang

Analytical Model of Foreshock Ion Interaction With a Discontinuity: A Statistical Study

• DOI: 10.1029/2022ja031162
• 发表时间: 2023-04
• 期刊: Journal of Geophysical Research: Space Physics
• 作者: T. Liu;A. Vu;V. Angelopoulos;Hui Zhang