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

该项目将利用实验室实验研究宇宙物体的磁层。 当流动的等离子体（如太阳风）撞击磁障碍物（如行星）时，磁层就会形成，并且是空间天气系统的组成部分。 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，例如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建和探索这些“迷你”磁层的人工版本。 这项研究将利用这些实验的高重复性，提供前所未有的高分辨率动态磁层三维图。 这些结果将推进我们对最小尺度磁层的基本理解，反过来，也将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劳动力市场做好准备。微型磁层为研究传统上采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等离子体流与偶极磁体耦合来创建离子尺度的磁层，该偶极磁体嵌入加州大学洛杉矶的大型等离子体设备（LAPD）的均匀磁化等离子体中。 高重复实验将产生高分辨率的体积数据集，以便1）检查一系列偶极磁体和等离子体参数的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场方向的依赖性，3）观察弓形激波的形成，以及4）与三维粒子模拟进行比较。 研究结果将有助于验证数值模拟和磁层模型，并补充航天器对小型磁层的观测，如与彗星和月球磁异常有关的观测。该奖项反映了NSF的法定使命，并被认为值得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来支持。

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.