CAREER: Impact of Plasma Species, Mixing and Ionization Fraction on Drift-Wave Turbulence and Transport

该奖项的部分资金来自《2021年美国救援计划法案》(公法117-2)。这一职业奖支持使用实验和计算方法相结合的等离子体湍流研究。宇宙中99%的可见物质是等离子体，这是一种物质状态，当气体被加热到足够高的温度，从原子中剥离电子时，就会产生带电粒子云。实验和观测表明，等离子体可以是湍流的，表现出与在流体中观察到的类似的动力学。在研究等离子体中的湍流时，通常假设等离子体只由电子和一种离子组成，而这些云是100%电离的。然而，在现实中，等离子体并不是完全电离的，中性粒子的存在会影响湍流的动力学。此外，等离子体通常包含多个离子物种，这意味着单个离子可能具有不同的质量和电荷。即使是很小浓度的多种离子，也会对湍流产生非线性影响，而这些方面在目前的模型和实验中往往被忽略。更好地了解混合离子物种等离子体的作用以及中性粒子的影响，可以为空间天气和核聚变发电厂的设计提供洞察。除了科学范围外，该奖项还支持创建一个可持续的K5计划，该计划旨在介绍与等离子体和湍流相关的主题。该项目将使用大型等离子体设备(LAPD)，这是加州大学洛杉矶分校基础等离子体科学设施中的一个线性磁化等离子体设备，用于研究漂移波等离子体湍流。LAPD可以改变中性压力以及等离子体密度和温度，从而有效地改变电离率和中性与等离子体的比例。通过专门扫描电子温度、密度和中性密度，实验将测量湍流和等离子体流动的变化。这些扫描将重复不同的血浆种类，并最终混合血浆种类。为了更好地解释实验，流体等离子体程序Hermes将被用来自洽地计算存在中性物质时的湍流和等离子体分布。模型和实验的结合将使人们更好地了解模型是否能够捕捉到各种(混合)等离子体物种和中性物质的动态，或者模型是否需要进一步开发。这一奖项反映了NSF的法定使命，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 award is funded in part under the American Rescue Plan Act of 2021 (Public Law 117-2). This CAREER award supports a study of plasma turbulence using a combination of experimental and computational approaches. 99% of all visible matter in the universe is a plasma, a state of matter commonly created when a gas is heated to high enough temperatures to strip electrons away from the atoms, creating a cloud of electrically charged particles. Experiments and observations have shown that plasmas can be turbulent, demonstrating similar dynamics to that observed in fluids. When studying the turbulence in plasmas, it is often assumed that plasmas only consist of electrons and one ion species, and these clouds are 100% ionized. However, in reality, plasmas are not fully ionized and the presence of neutral particles can influence the dynamics of turbulence. Moreover, plasmas often contain multiple ion species, which means that the individual ions can have a different mass and charge. Even small concentrations of multiple ion species can have non-linear effects on turbulence and these aspects are often neglected in current models and experiments. Better understanding of the role of mixed-ion species plasmas as well as the influence of neutral particles can provide insights into space weather and the design of nuclear fusion power plants. In addition to the scientific scope, this award supports creation of a sustainable K5 program built to introduce topics related to plasmas and turbulence.This project will use the LArge Plasma Device (LAPD), a linear magnetized plasma device within the Basic Plasma Science Facility at the University of California - Los Angeles, to study drift-wave plasma turbulence. LAPD has the possibility to change the neutral pressure as well as the plasma density and temperature, thus effectively allowing alteration of the ionization ratio and the neutral to plasma fraction. Through dedicated scans of electron temperature, density and neutral density, the experiments will measure the changes in turbulence and plasma flows. These scans will be repeated for different plasma species and eventually mixed plasma species. To better interpret experiments, a fluid plasma code HERMES will be used to self-consistently calculate turbulence and plasma profiles in the presence of neutral species. The combination of modeling and experiments will allow a better understanding of whether the models can capture the dynamics of various (mixed) plasma species and neutrals, or whether the models need to be further developed.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.