Laboratory Studies of Laser-Driven, Ion-Scale Mini-Magnetospheres on the LAPD

这个项目将使用实验室实验来研究宇宙物体的磁层。当流动的等离子体（如太阳风）撞击磁性障碍物（如行星）时，就会形成磁层，这是空间天气系统的一个组成部分。地球的磁层已经被航天器观测了几十年，但磁层也可以存在于更小的尺度上，比如彗星或小行星周围，这些都很难直接研究。这个项目将在实验室环境中创造和探索这些“迷你”磁球的人工版本。通过利用高重复性实验的能力，这项研究将提供一个前所未有的、高分辨率的动态磁层三维地图。这些结果将促进我们在最小尺度上对磁层的基本理解，进而提高我们对包括地球在内的行星磁层的建模能力。该项目还将为研究生提供高级培训和指导，使他们为美国的STEM劳动力做好准备。微型磁球提供了一个独特的环境来研究动力学尺度的等离子体物理，传统上是用数值模拟来模拟的。该项目将通过将超音速激光驱动等离子体流与嵌入均匀磁化等离子体的偶极磁铁耦合在一起，创造离子尺度的磁球，该等离子体是位于洛杉矶加州大学的大型等离子体装置（LAPD）。高重复实验将产生高分辨率的体积数据集，以便1)研究全球磁层结构在一系列偶极子磁铁和等离子体参数下的演变，2)研究磁层结构和磁重联动力学对偶极子场方向的依赖，3)观察弓形激波的形成，以及4)比较三维粒子胞内模拟。这些结果将有助于验证数值模拟和磁层模型，以及补充与彗星和月球磁异常相关的微型磁层的航天器观测。该奖项反映了美国国家科学基金会的法定使命，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。

This project will use laboratory experiments to study magnetospheres of cosmic objects. Magnetospheres form when a flowing plasma, like the solar wind, impacts a magnetic obstacle, like a planet, and are an integral part of space weather systems. Earth’s magnetosphere has been observed by spacecraft for decades, but magnetospheres can also exist on much smaller scales, such as around comets or asteroids that are difficult to study directly. This project will create and explore artificial versions of these “mini” magnetospheres in a laboratory environment. By leveraging the ability of the experiments to be carried out with high repeatability, this study will provide an unprecedented, high-resolution three-dimensional map of a dynamic magnetosphere. The results will advance our fundamental understanding of magnetospheres at the smallest scales and, in turn, improve our ability to model planetary, including Earth's, magnetospheres. This project will also provide advanced training and mentorship to graduate students to prepare them for the U.S. STEM workforce.Mini-magnetospheres provide a unique environment to study kinetic-scale plasma physics that have traditionally been modeled with numerical simulations. This project will create ion-scale magnetospheres by coupling a supersonic, laser-driven plasma flow with a dipole magnet embedded in the uniform, magnetized plasma of the Large Plasma Device (LAPD) at the University of California, Los Angeles. High-repetition experiments will produce highly-resolved, volumetric datasets in order to 1) examine the evolution of global magnetospheric structure for a range of dipole magnet and plasma parameters, 2) study the dependence of magnetospheric structure and magnetic reconnection dynamics on the orientation of the dipole field, 3) observe the formation of bow shocks, and 4) compare to 3D particle-in-cell simulations. The results will help validate numerical simulations and magnetospheric models, as well as complement spacecraft observations of mini-magnetospheres such as those associated with comets and lunar magnetic anomalies.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.