SHINE: Connecting Electron Thermodynamics and Microphysical Processes: A Puzzle for the Evolution of the Solar Wind

SHINE：连接电子热力学和微物理过程：太阳风演化之谜

• 批准号: 1622498
• 负责人: Chadi Salem
• 金额: $ 36万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-15 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1622498&HistoricalAwards=false
• 关键词: SHINE; Connecting; Electron; Thermodynamics; Microphysical

For a long time, it has been unclear and a matter of debate to what degree electron-kinetic effects play a role for the acceleration and the evolution of the solar wind compared to other processes, such as the dissipation of turbulent fluctuations. For the first time, our observational capabilities, with the unprecedented quality of the solar cycle worth of Wind electron data that we are producing, combined with a theoretical analysis will allow us to quantitatively connect electron thermodynamics in the solar wind and microphysical processes and better determine the role of electrons for the evolution of the solar wind. This 3-year SHINE project is expected to improve present understanding of the physical processes that are relevant for the generation and evolution of the solar wind from a very fundamental plasma-physical perspective based on first principles. It will also provide much needed input for the development of predictive physics-based solar-wind models. Including more accurate description of electron physics in such models will lead to major improvements of our understanding of space-weather processes, the propagation of energetic-particle events, as well as the propagation of cosmic rays throughout the heliosphere.This 3-year SHINE project describes an integrated research program to study the microphysical processes that regulate the kinetic and non-thermal features of solar wind electrons, like the electron core and halo drifts, and the electron strahl structure. It will investigate the micro-instabilities generated by drifts, heat flux and temperature anisotropy, as well as their contributions to solar wind turbulence. The research will be based on in-situ observations of solar wind electron distribution functions, proton measurements, as well as magnetic field and plasma wave data from the Wind spacecraft. A hot plasma dispersion solver will be used to determine the theoretical thresholds and growth rates of electron-driven micro-instabilities.The electron microphysical processes addressed in this proposal have a broader application than the interplanetary medium, as they occur in the solar corona, the coronae of other stars and compact astrophysical objects, and in other more exotic environments in the universe such as jets and supernova blast waves. Furthermore, the topic of electron microphysics in the solar wind and in space plasma is one of the primary science focus topics by the heliophysics community in the USA, in particular SHINE. In the past, the project team has convened dedicated sessions at the NSF-funded SHINE Workshops in 2014 and 2015, which have received very positive feedback from the heliophysics community. The investigators plan to continue to lead the focus group and the science discussions to foster more, multi-disciplinary, collaborations within the space physics community, involving theory, numerical simulations, observations and data analysis. As part of this project, they propose a follow-up session at the 2016 SHINE Workshop. This science topic is also of great importance in the preparation of the upcoming NASA mission Solar Probe Plus and ESA mission Solar Orbiter, one of their key science goals being to explore in-situ the fundamental microphysical plasma processes at the origin of the heating of the solar corona, acceleration of the solar wind and the evolution of the heliosphere including CMEs and transients. This research project will foster a close work collaboration between the UC Berkeley and the UNH. It will support two young researchers in early phases of their scientific careers and a graduate student at UC Berkeley. The research and EPO agenda of this project supports the Strategic Goals of the AGS Division in discovery, learning, diversity, and interdisciplinary research.

长期以来，与其他过程（例如湍流波动的消散）相比，电子动效应在太阳风的加速和演化中发挥了多大作用，这一点一直不清楚，也存在争议。 我们的观测能力，以及我们正在产生的太阳周期中前所未有的风电子数据质量，与理论分析相结合，将使我们能够定量地将太阳风和微物理过程中的电子热力学联系起来，并更好地确定电子在太阳风演化中的作用。 这个为期 3 年的 SHINE 项目预计将基于第一原理，从非常基本的等离子体物理角度，提高目前对与太阳风的产生和演化相关的物理过程的理解。 它还将为基于物理的预测太阳风模型的开发提供急需的输入。 在此类模型中包含对电子物理的更准确描述将大大提高我们对空间天气过程、高能粒子事件的传播以及宇宙射线在整个日光层的传播的理解。这个为期 3 年的 SHINE 项目描述了一个综合研究计划，用于研究调节太阳风电子的动力学和非热特征的微物理过程，例如电子核心和晕漂移以及电子斯特拉尔结构。 它将研究由漂移、热通量和温度各向异性产生的微观不稳定性，以及它们对太阳风湍流的影响。 该研究将基于对太阳风电子分布函数、质子测量以及来自风航天器的磁场和等离子体波数据的现场观测。 热等离子体色散求解器将用于确定电子驱动的微不稳定性的理论阈值和增长率。本提案中讨论的电子微物理过程比行星际介质具有更广泛的应用，因为它们发生在日冕、其他恒星和致密天体物理物体的日冕，以及宇宙中其他更奇特的环境，例如喷流和超新星爆炸波。 此外，太阳风和空间等离子体中的电子微物理主题是美国太阳物理学界（尤其是 SHINE）的主要科学焦点主题之一。 过去，项目团队曾于 2014 年和 2015 年在 NSF 资助的 SHINE 研讨会上召开过专门会议，得到了太阳物理学界非常积极的反馈。 研究人员计划继续领导焦点小组和科学讨论，以促进空间物理学界内更多的多学科合作，包括理论、数值模拟、观测和数据分析。 作为该项目的一部分，他们提议在 2016 年 SHINE 研讨会上召开后续会议。 这一科学主题对于即将到来的 NASA 太阳探测器 Plus 任务和 ESA 太阳轨道器任务的准备也非常重要，它们的关键科学目标之一是现场探索太阳系加热源头的基本微物理等离子体过程。日冕、太阳风的加速和日光层的演化，包括日冕物质抛射和瞬变。 该研究项目将促进加州大学伯克利分校和新罕布什尔大学之间的密切工作合作。 它将支持两名处于科学职业早期阶段的年轻研究人员和一名加州大学伯克利分校的研究生。 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。