Collaborative Research: Aggregation and Electrification in a Laboratory-scale Volcanic Plume

火山爆发对空中交通、基础设施、人类健康和全球气候都有重大影响。由于危险的条件、喷发时间的不确定性和遥远的喷发地点，这些事件对监测构成挑战。减轻危害需要(1)远程探测喷发条件和(2)了解火山上方的火山灰分布，然后将其分散到上层大气中。这项研究将通过探索湍流、火山灰颗粒动力学和电气化之间的联系来解决这两个关键问题。火山爆发后，火山灰颗粒遇到湍流，这可以促进颗粒相互作用，带电和聚集。带电的羽流可以引发火山闪电，这是一种壮观的现象，可以用来研究近乎实时的危险喷发。这些放电会产生宽带辐射（例如无线电波），这些辐射可以携带有关流内部的信息，远远超出火山附近的范围。电力也可以使聚集的粒子结合，加速它们落回地面。此外，粒子聚集受到羽流和大气中水分的强烈影响。这些过程对火山灰的危害至关重要，但它们的建模具有挑战性。湍流、聚集和电气化的影响密切相关，但它们的相互作用从未被实验量化。因此，有必要改进对这些影响的测量，这可以用来建立精确的火山灰运输模型。该项目将通过参与这些实验和科学传播培训来加强对三名研究生的教育，通过这些培训，他们将开发动手演示以进行公众宣传。该项目旨在通过高精度实验和先进的计算模型来改进对火山羽流行为的预测。研究小组将对充满粒子的湍流射流进行实验测量，检查聚集场和电场。高分辨率光学技术将研究有和没有水分的粒子混合物中的湍流和聚集。电子传感器将测量粒子的电荷，这些测量结果将与火山喷发条件的模型联系起来。结果将被整合到一个计算模型中，该模型可用于远程检查火山羽流状况。此外，这项研究将在俄勒冈科学与工业博物馆（OMSI）和史密森学会（Smithsonian Institution）通过一系列实际演示向公众展示。这个项目得到了地球物理和岩石地球化学两个项目的支持。该项目由地球物理项目、岩石和地球化学项目以及地球科学部共同资助，以支持在各种机构类型中增加研究能力、能力和基础设施的项目，如GEO EMBRACE DCL所述。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。

Explosive volcanic eruptions have significant impacts on air traffic, infrastructure, human health, and global climate. These events are a challenge to monitor due to hazardous conditions, uncertainty in eruption timing, and remote eruption locations. Hazard mitigation requires (1) remote detection of eruption conditions and (2) an understanding of the ash distribution above the volcano, which can then disperse across the upper atmosphere. This study will address both critical issues by exploring the link between turbulence, ash particle dynamics, and electrification. Following an eruption, volcanic ash particles encounter turbulence, which can promote particle interaction, electric charging, and clustering. Electrified plumes can trigger volcanic lightning, a spectacular phenomenon that may be used to study hazardous eruptions in near real-time. These discharges generate broadband radiation (e.g. radio waves) that can carry information about the interior of the flow far beyond the immediate vicinity of the volcano. Electrical forces can also cause clustered particles to combine, accelerating their fall back to the ground. In addition, particle aggregation is strongly influenced by moisture in the plume and the atmosphere. These processes are critical to the hazards of volcanic ash, yet they are challenging to model. The effects of turbulence, aggregation, and electrification are closely linked, but their interactions have never been experimentally quantified. Hence, there is a need for improved measurements of these effects, which can be used to create accurate models of volcanic ash transport. This project will enhance the education of three graduate students through participation in these experiments and through scientific communication training through which they will develop hands-on demonstrations for public outreach. This project aims to develop improved predictions of volcanic plume behavior through high-accuracy experiments and advanced computational models. The research team will conduct experimental measurements of turbulent jets filled with particles, examining both aggregation and electric fields. High-resolution optical techniques will study turbulence and clustering in the particle mixtures, both with and without moisture. Electrical sensors will measure particle charging, and the measurements will be linked to models of the eruption conditions. The results will be integrated into a computational model, which can be used to examine volcanic plume conditions remotely. In addition, the research will be presented to the public through a series of hands-on demonstrations at the Oregon Museum of Science and Industry (OMSI) and the Smithsonian Institution. This project was supported by both the Geophysics and the Petrology and Geochemistry programs. This project is jointly funded by the Geophysics Program, Petrology and Geochemistry Program, and the Division of Earth Sciences to support projects that increase research capabilities, capacity and infrastructure at a wide variety of institution types, as outlined in the GEO EMBRACE DCL.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.