CAREER: Toward Understanding Solar Wind Turbulence in the Inner Heliosphere

确定加热日冕和加速太阳风的确切机制是太阳-日光层物理学中两个最重要的问题，也是帕克太阳探测器（PSP）使命的首要目标之一。 这一使命计划于2018年夏季发射，将访问任何航天器从未探索过的近太阳区域，提供对9.5至55个太阳半径（从太阳中心测量）之间的内日光层的开创性现场和近距离遥感测量，比Helios使命近六倍。 这个为期五年的CAREER项目旨在提高目前对太阳附近湍流演化和结构的理解。 该项目还将有助于阐明能量如何从太阳表面传输到高层大气，以及这些能量如何消散以加热日冕并加速太阳风。 这一项目的主要广泛影响之一是，它将为解释PSP测量结果奠定理论基础，从而提高PSP使命的科学回报，这将对日光层物理学中的其他一些悬而未决的问题产生影响。 该项目小组将推出一种新颖的用户友好型软件工具，使学生能够利用数值模拟，在最少的科学计算知识的情况下，加强对空间等离子体物理学入门知识的学习。 数值模拟将在入门课程中发挥的作用将密切反映模拟在现代等离子体研究中发挥的作用，即，当分析进展不再可能时，促进对基础物理学的理解。 软件界面将允许学生快速解决数值问题，从数值解中获得直觉，以帮助加强对基本概念的理解。 该项目的另一个主要的更广泛的影响是，在其结束时，该工具的一个经过充分测试的工作版本将在GNU开源许可证下在线提供，以便扩大其等离子体物理问题库并在其他研究机构中使用。 还将对这一软件工具进行调整，以便向公众传播这一项目的研究成果，并使他们了解空间等离子体研究的相关性以及空间等离子体方案将在今后几十年中促成的革命性发现。 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。该项目有望提高对近太阳环境中湍流起源和演变的理解，从低日冕中观察到的阿尔芬波到上日冕和太阳风中的湍流波动。 这项调查将结合联合收割机理论，高分辨率数值模拟和现有的观测，为解释PSP前所未有的测量奠定基础。 该项目旨在实现以下具体科学目标：㈠调查湍流如何从日冕中的AW运动演变为日心距离较大时充分发展的AW湍流; ㈡确定控制惯性范围功率谱的比例律、交叉螺旋度和湍流中剩余能量的作用以及这些特性如何取决于日心距离;（三）调查的作用，这种动荡发挥的权力法律的磁场能量谱的波动之间的0.3 Au和0.4 Au的太阳神测量观察;和，（四）建立预测的性质的湍流波动的PSP将测量。 这项CAREER调查也是及时的，因为它将在2018年底第一次测量可用之前为解释PSP信号奠定理论和数值框架。 这项研究的结果与未来的PSP观测相结合，不仅有助于扩大我们对该地区阿尔夫文湍流基本原理的了解，但将导致变革性的进展，以确定阿尔文湍流的可行性，作为一个主要的机制，加热日冕和加速太阳风。这一奖项反映了NSF的法定使命，并已被认为是值得支持，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。

Determining the exact mechanisms that heat the corona and accelerate the solar wind are two of the most important problems in solar-heliospheric physics, as well as one of the top priority goals of the Parker Solar Probe (PSP) mission. This mission, which is scheduled to launch in the summer of 2018, will visit the near-Sun regions never explored before by any spacecraft, providing groundbreaking in-situ and close-by remote sensing measurements of the inner heliosphere between 9.5 and 55 solar radii (measured from the center of the Sun), reaching up to six times closer than the Helios mission. This five-year CAREER project is aimed at improving present understanding of the evolution and structure of turbulence close to the Sun. The project will also help elucidate how energy is transported from the solar surface to its upper atmosphere and how this energy is dissipated to heat the solar corona and accelerate the solar wind. One of the main broader impacts of this project is that it will enhance the scientific return of the PSP mission by laying the theoretical foundations for interpretation of PSP measurements, which will have repercussions in a number of other outstanding questions in heliospheric physics. The project team will introduce a novel and user friendly software tool that will allow students to use numerical simulations, with minimal knowledge of scientific computing, to enhance learning of introductory space plasma physics. The role that numerical simulations will play in the introductory courses will closely mirror the role that simulations play in modern plasma research, i.e., to facilitate understanding of the underlying physics when analytical progress is no longer possible. The software interface will allow students to quickly solve numerical problems to gain intuition from the numerical solution to help reinforce understanding of the underlying concepts. Another main broader impact of this project is that, at its conclusion, a fully tested and working version of this tool will be made available online under the GNU open-source license, to allow for the expansion of its plasma physics problems base and use in other research institutions. This software tool will also be adapted to disseminate with the general public the research outcomes of this project, and inform them on the relevance of space plasma research and the revolutionary discoveries that the PSP will enable in the decades to come. The research and EPO agenda of this CAREER project supports the Strategic Goals of the AGS Division in discovery, learning, diversity, and interdisciplinary research.This CAREER is expected to provide an improved understanding of the origin and evolution of turbulence in the near-Sun environment, from the Alfven waves observed in the low corona to turbulent fluctuations in the upper corona and the solar wind. This investigation will combine theory, high-resolution numerical simulations and existing observations to lay the groundwork for the interpretation of the unprecedented measurements by the PSP. The project aims to accomplish the following specific science goals: (i) Investigate how turbulence evolves from AW motions in the solar corona to fully developed AW turbulence at larger heliocentric distances; (ii) identify scaling laws governing the inertial-range power spectrum, the role of cross- helicity and residual energy in the turbulence and how such properties depend on the heliocentric distance; (iii) investigate the role that this turbulence plays in power laws of the magnetic energy spectrum of fluctuations observed by Helios measurements between 0.3 AU and 0.4 AU; and, (iv) establish predictions of the properties of turbulent fluctuations that the PSP will measure. This CAREER investigation is also timely, because it will lay the theoretical and numerical framework needed for interpretation of the PSP signals before the first measurements become available at the end of 2018. The outcome of this research combined with the future PSP observations will not only contribute to expand our knowledge of the fundamentals of Alfvenic turbulence in this region, but will lead to transformative advances towards determining the viability of Alfvenic turbulence as a major mechanism for the heating of the corona and the acceleration of the solar wind.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.