Coupled Kinetic Physics of Protons and Electrons in the Solar Wind

太阳风中质子和电子的耦合动力学物理

• 批准号: 1842643
• 负责人: Peter Yoon
• 金额: $ 36万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-15 至 2022-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1842643&HistoricalAwards=false
• 关键词: Coupled; Kinetic; Physics; Protons; Electrons

The problem of solar wind modeling has been of historical significance. The related research is ongoing, and most models rely on macroscopic (fluid) models of the solar wind. When kinetic effects, such as wave-particle interaction, are considered, however, the approach is usually not self-consistent in that certain types of wave turbulence is presupposed, and the wave spectra are modeled. In contrast, the theoretical model to be developed as part of this three-year project will be fully kinetic and self-consistent. This will significantly advance the knowledge in the field of heliospheric physics. The model to be developed as part of this project will predict a particular state in which the solar wind plasma exists given a set of parameters, allowing the observed quantities to be tested against historic spacecraft data as well the planned measurements of the near-Sun environment that will be obtained by the Parker Solar Probe. Although the present project is a theoretical one, rather than one involving data analysis, the resulting prediction may help experimentalists better interpret the past and future spacecraft data. This has the potential to advance knowledge in a related, but different field of expertise, namely experimental heliophysics.This three-year research project will investigate theoretically how the kinetic coupling of electrons and ions (protons) via collisional and instability processes affect the large-scale dynamics in the expanding solar wind. The specific problem to be investigated relates to how the dynamically coupled solar wind electrons and protons contribute to the near isotropization of their temperatures -- an observed phenomena which has not yet been satisfactorily explained theoretically. The PI's preliminary work based upon the assumption of bi-Maxwellian particle distribution shows that collisional process may be the dominant mechanism for the isotropization of temperatures, but the instabilities are important too for limiting the upper/lower bounds of temperature anisotropies. This project aims to extend the preliminary work by relaxing the assumption of bi-Maxwellian model in both instability analysis and collisional transport calculation. The full kinetic equations for particles and waves, as well as the dispersion relation, will be solved by grid-based numerical scheme. The collisional transport equation will also be solved by relaxing the assumption of bi-Maxwellian models. Finally, the effects of inhomogeneities will be rigorously investigated by solving the macro-microscopic kinetic equation.The research on the theoretical modeling of the solar wind is important from the broader perspective of understanding and characterizing fundamental processes that take place within the heliosphere and throughout the universe. Discovering and understanding the basic physical processes in the immediate near-Earth environment and in the wider universe is essential for future human explorations of the universe, and it also has a space environmental impact, as the modern civilization is increasingly dependent on electromagnetic conditions in outer space. Developing an accurate model of the solar wind contributes to such a wider goal. From the perspective of education and training, the present proposal involves a young post-doctoral research associate, which is a major strength in terms of Broader Impacts. It is important for the healthy scientific future of our nation -- and the entire human society -- that a steady stream of young scientists are educated and trained in STEM disciplines. The PI has in the past always strived to educate and widely disseminate the scientific knowledge acquired during his career to younger generation of scientists both from the U.S. and worldwide. The present proposal will thus have a broader impact on the education and training of a young scientist. 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.

太阳风模型问题具有重要的历史意义。相关研究仍在进行中，大多数模型依赖于太阳风的宏观(流体)模型。然而，当考虑波粒相互作用等动力效应时，这种方法通常不是自洽的，因为假设了某些类型的波浪湍流，并模拟了波谱。相比之下，作为这个为期三年的项目的一部分而开发的理论模型将是完全动态和自我一致的。这将极大地促进日光层物理领域的知识。作为该项目的一部分开发的模型将在给定一组参数的情况下预测太阳风等离子体存在的特定状态，从而能够对照航天器的历史数据以及帕克太阳探测器将获得的近太阳环境计划测量结果对观测量进行测试。虽然目前的项目是一个理论项目，而不是一个涉及数据分析的项目，但由此产生的预测可能有助于实验者更好地解释过去和未来的航天器数据。这个为期三年的研究项目将从理论上研究电子和离子(质子)通过碰撞和不稳定过程的动力学耦合如何影响不断膨胀的太阳风中的大尺度动力学。需要研究的具体问题涉及太阳风电子和质子的动态耦合如何导致它们的温度接近各向同性--这一观察到的现象尚未从理论上得到令人满意的解释。PI基于双麦克斯韦粒子分布假设的初步工作表明，碰撞过程可能是温度各向同性的主要机制，但不稳定性对于限制温度各向异性的上下限也是重要的。本项目旨在通过放宽双麦克斯韦模型在不稳定性分析和碰撞输运计算中的假设来扩展前期工作。粒子和波的完整运动方程以及色散关系将采用基于网格的数值格式进行求解。通过放宽双麦克斯韦模型的假设，碰撞输运方程也将得到求解。最后，将通过求解宏观-微观动力学方程来严格研究不均匀性的影响。从更广泛的角度研究太阳风的理论建模对于理解和描述发生在日光层和整个宇宙中的基本过程是重要的。随着现代文明对外层空间电磁条件的日益依赖，发现和了解近地环境和更广阔宇宙中的基本物理过程对于未来人类探索宇宙是至关重要的，这也会对空间环境产生影响。开发一个准确的太阳风模型有助于实现这样一个更广泛的目标。从教育和培训的角度来看，本提案涉及一名年轻的博士后研究助理，从更广泛的影响来看，这是一大优势。对于我们国家和整个人类社会的健康科学未来来说，源源不断的年轻科学家接受STEM学科的教育和培训是重要的。过去，PI一直致力于向来自美国和世界各地的年轻一代科学家教育和广泛传播他在职业生涯中获得的科学知识。因此，本提案将对青年科学家的教育和培训产生更广泛的影响。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

Two-fluid approach to weak plasma turbulence

弱等离子体湍流的双流体方法

• DOI: 10.1088/1361-6587/ac2e40
• 发表时间: 2021
• 期刊: Plasma Physics and Controlled Fusion
• 影响因子: 2.2
• 作者: Yoon, Peter H

Electromagnetic instabilities of low-beta alpha/proton beams in space plasmas

空间等离子体中低βα/质子束的电磁不稳定性

• DOI: 10.1007/s10509-020-03823-4
• 发表时间: 2020
• 期刊: Astrophysics and Space Science
• 影响因子: 1.9
• 作者: Rehman, M. A.;Shaaban, S. M.;Yoon, P. H.;Lazar, M.;Poedts, S.
• 通讯作者: Poedts, S.

Polarization vector formalism of plasma weak turbulence

等离子体弱湍流的偏振矢量形式

• DOI: 10.1063/5.0070559
• 发表时间: 2021
• 期刊: AIP Advances
• 影响因子: 1.6
• 作者: Yoon, Peter H.

Quasilinear Model of Jovian Whistler Mode Emission

• DOI: 10.1029/2021ja029930
• 发表时间: 2021-11
• 期刊: Journal of Geophysical Research: Space Physics
• 作者: P. Yoon;J. Menietti;W. Kurth;F. Allegrini;S. Bolton

Proton cyclotron and mirror instabilities in marginally stable solar wind plasma

边缘稳定的太阳风等离子体中的质子回旋加速器和镜子不稳定性

• DOI: 10.1093/mnras/stab3286
• 发表时间: 2021
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: Yoon, P. H.;Sarfraz, M.;Ali, Z.;Salem, C. S.;Seough, J.
• 通讯作者: Seough, J.