AGS-PRF: The Effects of Nonlinearities on the Onset and Evolution of Microinstabilities in Solar Plasma

地球空间科学博士后研究是分析，计算和观测工作的组合，将在亚利桑那大学克里斯托弗·克莱因教授的监督下进行。该项目解决了太阳物理学中关于太阳风如何被激发的公开问题，以及一般来说，由于粒子与磁场的相互作用，天体物理等离子体如何被加热。这项工作很重要，因为宇宙中绝大多数可见物质预计都处于等离子体状态，在这种状态下，原子被分解成电子和离子，这些电子和离子受到磁场和电场的强烈影响。这项研究对于解释帕克太阳探测器即将进行的观测特别及时。除了进行前沿研究，首席研究员（PI）还将指导暑期学生的研究项目，并开发一个关于空间物理的本科教育模块，这将有助于她的专业发展。微不稳定性在包括太阳风在内的天体物理等离子体的能量转移和演化中发挥着重要作用。大多数描述的演变和发病的微观不稳定性只包括线性项，忽略了非线性效应。然而，许多这些不稳定性的发病和演变是高度依赖于粒子速度分布函数的非热功能，特别是在有限振幅磁场中的被困粒子的区域。在这项博士后研究中要调查的主要问题是（i）在何种程度上非线性效应，如捕获和通过粒子，影响太阳等离子体中的微不稳定性的发生和演变，以及（ii）参数制度的非线性需要考虑。该项目将开发一个分析模型的演变和发病的不稳定性，准线性理论和PI的论文工作的捕获和通过粒子。将利用动力学模拟并结合对太阳风中观测到的波动进行统计分析来验证分析模型，首席研究员将指导亚利桑那大学一名REU学生的研究项目，并开发一个教育模块，向本科生介绍空间科学和等离子体物理学方面的当前研究问题。该奖项反映了NSF的法定使命，并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，被认为值得支持。

The postdoctoral study in geospace science is a combination of analytical, computational, and observational work to be conducted under the supervision of Prof. Kristopher Klein at the University of Arizona. The project addresses open questions in solar physics about how the solar wind is energized, and in general, about how astrophysical plasmas are heated due to particle interactions with magnetic fields. This work is important as the vast majority of visible mass in the universe is expected to be in the plasma state, in which atoms are broken up into electrons and ions that are strongly influenced by magnetic and electric fields. The study is particularly timely to interpret forthcoming observations from the Parker Solar Probe. In addition to doing cutting-edge research, the principal investigator (PI) will also mentor a summer student’s research project and develop an undergraduate educational module on space physics, which will contribute toward her professional development.Microinstabilities are known to play a large role in the energy transfer and evolution of astrophysical plasmas including the solar wind. Most descriptions of the evolution and onset of microinstabilities only include linear terms, ignoring nonlinear effects. However, the onset and evolution of many of these instabilities is highly dependent on non-thermal features of the particle velocity distribution function, in particular, regions of trapped particles in finite amplitude magnetic fields. The primary questions to be investigated in this postdoctoral study are (i) the extent to which nonlinear effects, such as trapped and passing particles, affect the onset and evolution of microinstabilities in the solar plasma, and (ii) the parameter regimes where the nonlinearities need to be taken into account. The project will develop an analytical model for the evolution and onset of the instabilities, drawing on quasilinear theory and the PI’s thesis work on trapped and passing particles. The analytical model will be validated using kinetic simulations in conjunction with a statistical analysis of fluctuations observed in the solar wind.The principal investigator will mentor an REU student’s research project at the University of Arizona and develop an educational module to introduce undergraduates to current research questions in space science and plasma physics. This module will be made available to the scientific as well as education community.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.