Collaborative Research: Three-Dimensional Stability of Kinetic Flux Rope Structures in a Collisionless Magnetized Plasma

合作研究：无碰撞磁化等离子体中动能通量绳结构的三维稳定性

• 批准号: 2010393
• 负责人: Kai Germaschewski
• 金额: $ 14.43万
• 依托单位: University of New Hampshire
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2010393&HistoricalAwards=false
• 关键词: Collaborative; Research; Three; Dimensional; Stability

This project will theoretically and computationally study formation of self-organized structures in a plasma. Most observable matter in the universe is in the form of a plasma, consisting of electrically charged particles with electrons freed from atoms. In a plasma, the electrons and the charged atoms (the ions) move quasi-randomly, but their spatial distribution and movement can produce electric and magnetic fields leading to formation of plasma structures with sizes much larger than atomic sizes but much smaller than the volume of the whole plasma. Such small structures can fundamentally change the properties of plasmas. However, whether and how such structures can form is still poorly understood and will be pursued within this project. Results from this research will increase our understandings of properties of space, astrophysical, and laboratory plasmas, with societally important applications for space weather prediction and future fusion energy devices. This collaborative project will support a PhD student at University of Alaska Fairbanks, as well as a PhD student at University of New Hampshire. The students will receive training in both theory and numerical simulations.High temperature plasmas can be considered collisionless, with particle distributions in a collisionless plasma often deviating from a Maxwellian. While the forms of such non-Maxwellian distributions are important, it is also important to explore how small-scale kinetic structures can exist in such plasmas, with the Bernstein-Greene-Kruskal (BGK) modes in 1D being one example. This project will perform numerical simulations using the state-of-the-art Particle-In-Cell (PIC) code "PSC" to study the stability of analytic multi-dimensional solutions of localized kinetic structures in the form of magnetic flux ropes satisfying the Vlasov-Poisson-Ampère system of equations. Possible formation mechanisms for the generation of stable two-dimensional or three-dimensional localized kinetic structures will also be studied numerically. The main goal of this research is to characterize quantitatively the conditions under which kinetic structures can be stable. This project is expected to produce new understanding of small-scale kinetic physics in collisionless magnetized plasmas. New insights obtained through this project will have impact on fundamental plasma theory, as well as affect frontier problems in laboratory, space and astrophysical plasmas. For example, it can have significant implication for understanding the process of magnetic reconnection, where recent large-scale kinetic simulations have discovered the generation of small kinetic scale flux ropes during magnetic reconnection. Small-scale kinetic structures have also been observed by the Magnetospheric Multiscale (MMS) mission, which has the main objective of studying magnetic reconnection in space. Moreover, this project can impact other fields in science since the Vlasov equation is widely applied in many different physical systems. This project is jointly funded by the Division of Physics and the Established Program to Stimulate Competitive Research (EPSCoR).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.

该项目将理论和计算研究等离子体中自组织结构的形成。宇宙中最可观察到的物质是血浆的形式，由带电的电动颗粒组成，这些颗粒具有从原子中释放的电子。在血浆中，电子和带电原子（离子）移动准随机，但是它们的空间分布和移动可以产生电场和磁场，从而导致形成的等离子结构，其大小远大于原子大小，但比整个血浆的体积小得多，但要小得多。如此小的结构可以从根本上改变等离子体的特性。但是，这种结构是否以及如何形成仍然是对该项目中的理解，并将在该项目中追求。这项研究的结果将提高我们对空间，天体物理和实验室等离子体的特性的理解，并在太空天气预测和未来的融合能源设备上使用社会重要的应用。这个合作项目将支持阿拉斯加大学Fairbanks大学的博士生，以及新罕布什尔大学的博士生。学生将接受理论和数值模拟的培训。高温等离子体可以视为无碰撞，而无碰撞等离子体中的粒子分布通常会偏离麦克斯韦式。尽管这种非麦克斯韦分布的形式很重要，但探索这种平原中如何存在小规模动力学结构，而伯恩斯坦 - 果岭 - 克鲁斯卡尔（BGK）模式在1D中是一个例子。该项目将使用最先进的粒子中的粒子（PIC）代码“ PSC”进行数值模拟，以研究局部动力学结构的分析多维溶液的稳定性，以满足vlasov-poisson-ampère等价系统的磁通循环的形式。还将研究稳定的二维或三维局部动力学结构的可能形成机制。这项研究的主要目标是定量表征动力学结构稳定的条件。预计该项目将在无碰撞磁化等离子体中对小规模动力学物理学产生新的了解。通过该项目获得的新见解将对基本等离子体理论产生影响，并影响实验室，空间和天体物理等离子体的前沿问题。例如，它可能对理解磁重新连接的过程具有重要意义，在这种情况下，最近大规模的动力学模拟发现了磁重新连接期间的小动力学量量绳索的产生。磁层多尺度（MMS）任务也观察到了小型动力学结构，该任务的主要目的是研究空间中的磁重新连接。此外，由于弗拉索夫方程广泛应用于许多不同的物理系统，因此该项目可能会影响科学领域的其他领域。该项目由物理学部和既定计划的计划（EPSCOR）共同资助。本奖反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响审查标准，通过评估被认为是宝贵的支持。