SHINE: Coronal and Interplanetary Magnetic Field: Structure, Topology, Flux Tubes, Transport, and Application to Energetic Particles

SHINE：日冕和行星际磁场：结构、拓扑、通量管、输运以及高能粒子的应用

• 批准号: 1156094
• 负责人: William Matthaeus
• 金额: $ 38.23万
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-03-01 至 2016-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1156094&HistoricalAwards=false
• 关键词: SHINE; Coronal; Interplanetary; Magnetic; Field

As the scientific motivation for this project, the principal investigator (PI) and his team note that the space physics community currently relies on solar magnetic field models that assume it is meaningful to represent flux tubes as coherent objects that extend over distances ranging from fractions of a solar radius to many Astronomical Units. In order to place this fundamental assumption on a firmer basis, the PI's team will examine the limitations of this "coherent flux tube" paradigm when magnetic fluctuations are present and they will study how to extend beyond this conceptual framework using several approaches. The team will apply magnetic field models and nonlinear transport theory to quantify Field Line Random Walk effects, as well as the flux tube meandering and "shredding" that causes the eventual breakdown of the standard flux tube scenario. The team will investigate these phenomena using "Reduced Magnetohydrodynamics" (Reduced MHD) physics models, an approach that is well tested in solar corona studies. The PI's team will also study the often neglected implications of isotropic field line and particle transport, where particle trapping becomes very important. The team will examine the relationship between field line transport and the intermittent character of real turbulent fields, and apply this knowledge to examine the well-known "dropouts" and "channeling" of solar energetic particles (SEPs) that have been observed. The team will investigate the time-dependent interaction of flux tubes by introducing the concept of "component interchange reconnection" and exploring its consequences for the topological structure of magnetic fields in the solar wind and in dynamical simulations of MHD turbulence. The broader impacts of this effort include improving our recognition of the limitations of existing flux tube models, and how these limitations apply to research areas ranging from astrophysics to space weather forecasting. In particular, this work will have an immediate impact on our understanding of the propagation of SEPs in a space weather context. The PI will also provide mentoring for several postdoctoral fellows and widely disseminate these research results at solar physics community workshops.

作为该项目的科学动机，主要研究员（PI）和他的团队指出，空间物理学界目前依赖于太阳磁场模型，该模型假设将通量管表示为相干物体是有意义的，这些物体的距离从太阳半径的几分之一延伸到许多天文单位。为了将这一基本假设置于更坚实的基础上，PI的团队将研究这种“相干通量管”范式在存在磁波动时的局限性，他们将研究如何使用多种方法扩展到这一概念框架之外。该团队将应用磁场模型和非线性传输理论来量化场线随机游走效应，以及导致标准通量管场景最终崩溃的通量管蜿蜒和“粉碎”。该团队将使用“简化磁流体力学”（简化MHD）物理模型来研究这些现象，这是一种在日冕研究中得到很好测试的方法。PI的团队还将研究经常被忽视的各向同性场线和粒子传输的影响，其中粒子捕获变得非常重要。该小组将研究场线传输和真实的湍流场的间歇性特征之间的关系，并将这一知识应用于研究已观察到的太阳高能粒子（SEP）的众所周知的“辍学”和“通道”。该小组将通过引入“组件交换重联”的概念，并探索其对太阳风磁场拓扑结构和MHD湍流动态模拟的影响，研究通量管随时间变化的相互作用。这项工作的更广泛的影响包括提高我们对现有通量管模型的局限性的认识，以及这些局限性如何适用于从天体物理学到空间天气预报的研究领域。特别是，这项工作将对我们理解空间天气背景下SEP的传播产生直接影响。PI还将为几名博士后研究员提供指导，并在太阳物理社区研讨会上广泛传播这些研究成果。