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

该项目将利用实验室实验来研究宇宙物体的磁层。当流动的等离子体像太阳风一样撞击像行星一样的磁障时，磁层就形成了，是空间天气系统的组成部分。几十年来，宇宙飞船一直在观测地球的磁层，但磁层也可以在小得多的尺度上存在，例如在难以直接研究的彗星或小行星周围。该项目将在实验室环境中创造和探索这些“迷你”磁层的人工版本。通过利用实验的高重复性，这项研究将提供前所未有的、高分辨率的动态磁层三维地图。这些结果将促进我们对最小尺度上的磁层的基本理解，进而提高我们对包括地球在内的行星磁层进行建模的能力。该项目还将为研究生提供高级培训和指导，为他们进入美国STEM工作队伍做好准备。微型磁层为研究传统上用数值模拟建模的动力学尺度等离子体物理提供了独特的环境。该项目将通过将超音速激光驱动的等离子体流与嵌入加州大学洛杉矶分校大型等离子体设备(LAPD)的均匀磁化等离子体中的偶极磁铁耦合来创建离子尺度的磁层。高重复实验将产生高分辨率的体积数据集，以便1)检查一系列偶极磁铁和等离子体参数下全球磁层结构的演变，2)研究磁层结构和磁重联动力学对偶极磁场方向的依赖，3)观察弓形激波的形成，以及4)与三维粒子单元模拟进行比较。这些结果将有助于验证数值模拟和磁层模型，并补充航天器对微型磁层的观测，例如与彗星和月球磁异常有关的观测。这一奖项反映了美国国家科学基金会的法定任务，并通过使用基金会的智力优势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.