Collaborative Research: Particle Energization in Turbulence and Magnetic Reconnection

这个为期三年的研究项目旨在提供一个关于粒子能量物理机制的基本知识框架，这可能需要明确确定太阳日冕的加热机制。此外，对磁重联和等离子体湍流中粒子能量的多尺度问题的基本见解（研究项目的主要目标）将提高实现预测极端空间天气事件影响的社会目标的能力，特别是通过这些机制加速危险的太阳高能粒子。等离子体湍流和磁重联是太阳物理学中的两大挑战问题，这两种尚未完全理解的机制的重叠和相互作用代表了太阳物理学研究的重要前沿。这个为期三年的研究项目针对这一前沿的一个主要未解问题，即：在小尺度上磁重联在等离子体湍流耗散中发挥多大程度的作用？为了在回答这个基本问题上取得进展，在这个项目中，将使用AstroGK和Gkeyll动力学模拟代码进行磁重联和等离子体湍流模拟。项目团队将使用导向中心分析和压力张量计算，以及单点场-粒子相关分析来研究粒子通电，以确定与无碰撞磁重联相关的特定通电机制的特征速度空间特征。最后，通过分析磁层多尺度（MMS）任务测量的电磁场和粒子速度分布函数，在湍流磁鞘等离子体中寻找这些特征。这个为期三年的项目将支持爱荷华大学空间等离子体物理学研究生的教育和博士论文研究。此外，将新的场-粒子相关技术用于分析日球等离子体中的粒子能量，可以随后应用于理解空间和天体物理等离子体中由于湍流、重连或无碰撞冲击而产生的等离子体加热和粒子加速的基本原理；这是2013年NRC太阳物理十年调查概述的太阳物理学界的主要目标。项目期间取得的研究成果将通过在国家和国际会议上向科学界作报告和在同行评议的文献中发表的方式广泛传播。这项研究的内容将被纳入面向所有年龄段的学校观众的公共宣传活动，以及关于等离子体物理学、天体物理学和空间物理学的公开讲座。该项目的研究和EPO议程支持AGS部门在发现、学习、多样性和跨学科研究方面的战略目标。该奖项反映了美国国家科学基金会的法定使命，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，被认为值得支持。

This three-year research project aims to provide an essential framework of knowledge about the physical mechanisms of particle energization that will likely be needed to make a definitive determination of the heating mechanism of the solar corona. Furthermore, fundamental insights into the multi-scale problem of particle energization in magnetic reconnection and plasma turbulence -- a major goal of the research project -- will lead to an improved ability to achieve the societal goal of predicting the impacts of extreme space weather events, in particular the acceleration of hazardous solar energetic particles by these mechanisms.Plasma turbulence and magnetic reconnection are two grand challenge problems in heliophysics, and the overlap and interplay of these two incompletely understood mechanisms represents an important frontier for heliophysics research. This three-year research project targets a major unanswered question on this frontier, namely: to what extent does magnetic reconnection play a role in the dissipation of plasma turbulence at small scales? In order to make progress in answering this fundamental question, during this project magnetic reconnection and plasma turbulence simulations will be performed using both the AstroGK and Gkeyll kinetic simulation codes. The project teams will investigate the particle energization using a guiding-center analysis and a pressure tensor calculation, along with a single-point field-particle correlation analysis to determine the characteristic velocity-space signatures of specific energization mechanisms associated with collisionless magnetic reconnection. Finally, these signatures will be sought in the turbulent magnetosheath plasma by analyzing the electromagnetic field and particle velocity distribution function measurements from the Magnetospheric Multiscale (MMS) mission.This three-year project will support the education and Ph.D. thesis research of a graduate student in space plasma physics at the University of Iowa. Furthermore, a refined implementation of the novel field-particle correlation technique to the analysis of particle energization in heliospheric plasmas can be subsequently applied to understand the fundamentals of plasma heating and particle acceleration in space and astrophysical plasmas due to turbulence, reconnection, or collisionless shocks; this is a major goal of the heliophysics community as outlined by the 2013 NRC Heliophysics Decadal survey. The research results obtained during the project will be disseminated broadly through presentations to the scientific community at national and international meetings and publication in the peer-reviewed literature. Elements of this research will be incorporated into public outreach events for school audiences of all ages as well as public lectures on plasma physics, astrophysics, and space physics. The research and EPO agenda of this project supports the Strategic Goals of the AGS Division in discovery, learning, diversity, and interdisciplinary research.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.