Thin Current Sheets and the Evolution of Auroral Forms

薄电流片是各种等离子体环境中普遍存在的现象。该项目将研究在极光产生区域驱动薄电流片动态演化的过程。极光弧线的动态演变导致了极光形状的快速扭曲、卷曲和折叠，使观看极光变得如此引人注目。这些运动是薄电流片中等离子体不稳定性相互作用的结果，从小尺度的动力学到整个极光加速区的大小都在运行。该项目将利用来自Reimei航天器的观测，该航天器首次提供极光形式的专用成像，并对驱动极光形式的粒子进行磁性共轭高时间分辨率测量。这些观测为对极光运动和结构进行定量分析提供了前所未有的机会，同时提供了驱动光学发射的粒子分布的细节。该项目将实施一种新的基于小波的技术，用于分析来自Reimei航天器的极光图像序列，以确定作为尺度函数的等离子体流动的涡度。涡度随洋流或能量通量(光度)的分布将提供确定在极光结构演化中占主导地位的过程的手段。卫星观测将通过使用和进一步开发包括电子惯性和电离层电阻率在内的3D、简化的MHD数值模拟而得到帮助。FAST航天器现有的统计场测量将用于增强雷美成像仪和粒子观测，以提供极光形式的更完整的电动力学表征，并与模拟结果进行比较。该项目将有助于增进我们对一个非常著名和经常观察到的公共利益现象的了解。它涉及与加州大学伯克利分校空间科学实验室的科学教育中心的合作。这项研究的结果将被纳入为主要从事非裔美国人和拉美裔学生教学的教师举办的一系列研讨会。该项目还通过为博士后学者和研究生研究员提供支持来促进教学、培训和学习。

Thin current sheets are a ubiquitous phenomena in a wide variety of plasma environments. This project will examine processes which drive the dynamic evolution of thin current sheets in the region where the auroras are generated. The dynamic evolution of auroral arcs is responsible for the rapid kinking, curling and folding of auroral forms that make watching the aurora so compelling. These motions are the consequence of the interaction of plasma instabilities in thin current sheets operating on scale sizes from small-scale kinetics up to the size of the full auroral acceleration region. This project will exploit observations from the Reimei spacecraft which provides the first dedicated imaging of auroral forms with magnetically conjugate high time resolution measurements of the particles which drive them. These observations provide the unprecedented opportunity for quantitative analysis of auroral motions and structuring to be performed while simultaneously providing details of the particle distributions driving the optical emissions. The project will implement a new wavelet-based technique for the analysis of sequences of auroral imagery from the Reimei spacecraft to ascertain the vorticity of plasma flows as a function of scale. The distribution of vorticity with current or energy flux (luminosity) will provide the means to identify which processes dominant in the evolution of the auroral structures. The satellite observations will be aided by the use and further development of a 3-D, reduced MHD numerical simulation that includes electron inertia and ionospheric resistivity. Existing statistical field measurements from the FAST spacecraft will be used to augment the Reimei imager and particle observations to provide a more complete characterization electrodynamics of the auroral forms and for comparison with simulation results. The project will help improve our understanding of a very well known and commonly observed phenomenon of public interest. It involves a collaboration with the Center for Science Education at the UC Berkeley Space Sciences Laboratory. The results from this research will be incorporated into a series of workshops for teachers who are primarily involved in teaching African-American and Latino students. The project also promotes teaching, training and learning by providing support for a postdoctoral scholar and graduate student researcher.