Collaborative Research: Study of Anisotropic Dust Interactions in the PK-4 Experiment

该奖项支持奥本大学和贝勒大学在国际空间站的等离子体Kristall-4(PK-4)实验中研究微重力下复杂等离子体的行为的合作努力。复杂等离子体，也称为尘埃等离子体，是浸泡在等离子体或电离气体中的微米大小的尘埃颗粒的集合。尘埃颗粒通常通过收集其表面的电子和离子而带电。当尘埃等离子体被置于外电场中时，尘埃颗粒与离子流之间的各向异性相互作用可导致形成丝状尘埃结构。各向异性相互作用取决于相互作用粒子的相对取向，已知出现在一些最有趣的复杂系统中，包括蛋白质和智能材料。在这些系统的研究中，一个基本的开放问题是各向异性相互作用如何导致结构的形成。这个项目使用分析、数值和实验相结合的方法来解决这个问题，以调查各向异性相互作用如何导致国际空间站(ISS)尘埃等离子体实验中的结构形成。该项目由物理系和已建立的激励竞争研究计划(EPSCoR)共同资助。该项目将使用几个PK-4活动的数据来研究导致丝状尘埃等离子体结构形成的各向异性尘埃相互作用势的形式和来源。从PK-4实验收集的数据将被用来使用统计分析和数据驱动的方法来量化结构各向异性作为等离子体条件的函数。尘埃和离子的分子动力学(MD)模拟将被用来计算尘埃-离子尾场势。机器学习(ML)模型将被应用于实验数据，以确定作为等离子体参数的函数的最可能的相互作用力形式。离子-尘埃分子动力学模拟和ML模型学到的相互作用力和相互作用势将应用于较大尘埃云的分子动力学模拟，以与实验数据进行验证。PK-4 BU设备是PK-4 ISS的地面复制品，具有额外的诊断能力，将用于确定等离子体条件和等离子体电离波开始之间的关系。最后，将使用一个解析模型来确定表示各向异性相互作用势的哈密顿量的能态的谱。该方法将用于确定PK-4丝状尘埃等离子体与其他丝状结构之间的关系，例如电流变材料和液晶。该奖项反映了NSF的法定使命，并已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 supports a collaborative effort between Auburn University and Baylor University to study behavior of a complex plasma under microgravity in the PlasmaKristall-4 (PK-4) experiment on the International Space Station. Complex plasmas, also known as dusty plasmas, are collections of micron-sized dust particles immersed in a plasma, or ionized gas. The dust grains typically become charged by collecting electrons and ions on their surface. When dusty plasmas are placed in external electric fields, anisotropic interactions between dust grains and ion flows can lead to the formation of filamentary dust structures. Anisotropic interactions, which depend on the relative orientation of interacting particles, are known to arise in some of the most interesting complex systems, including proteins and smart materials. A fundamental open question in the study of these systems is how anisotropic interactions lead to structure formation. This project addresses this question using a combined analytical, numerical, and experimental approach to investigate how anisotropic interactions lead to structure formation in dusty plasma experiments on the International Space Station (ISS). The project is jointly funded by the Division of Physics and the Established Program to Stimulate Competitive Research (EPSCoR).This project will use data from several PK-4 campaigns to investigate the form and origins of the anisotropic dust-dust interaction potential that leads to the formation of filamentary dusty plasma structures. Data collected from PK-4 experiments will be used to quantify structural anisotropy as a function of plasma conditions using statistical analysis and data-driven methods. Molecular dynamics (MD) simulations of dust and ions will be used to calculate the dust–ion wakefield potential. A machine learning (ML) model will be applied to experimental data to identify the most likely form of the interaction forces as a function of plasma parameters. Interaction forces and potentials learned with the ion-dust MD simulation and the ML model will be applied in MD simulations of larger dust clouds to validate against the experimental data. Experiments in the PK-4 BU device, a ground-based replica of the PK-4 ISS with additional diagnostic capabilities, will be used to determine the relationship between plasma conditions and the onset of plasma ionizations waves. Finally, an analytic model will be employed to determine the spectrum of energy states of the Hamiltonian representing the anisotropic interaction potential. This method will be used to determine the relationship between PK-4 filamentary dusty plasma and other filamentary structures, such as electrorheological materials and liquid crystals.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.