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Optimizing Aerodynamic Focusing Lenses for Nano- to Supermicron-Particles

Active Dates 9/1/2020-8/31/2024
Program Area EPSCoR-Experimental Program to Stimulate Competitive Research
Project Description
Aerodynamic lenses are used to efficiently deliver particles into aerosol mass spectrometers, where particle physical properties and chemical compositions are analyzed. These measurements are critical for understanding atmospheric aerosol processes related to air quality, cloud formation, radiative balance, and climate. However, existing aerodynamic lenses only effectively focus a portion (e.g., from 30 to 600 nanometers) of the atmospheric particle size range of interest (from approximately 10 nanometers to 10 micrometers). Therefore, current aerosol mass spectrometer measurements provide an incomplete picture of aerosol processes, missing information about climate-relevant aerosols including new particles formed from gas precursors and large particles such as sea salt and mineral dust. The proposed work aims to improve aerodynamic lenses to cover a much wider size range from nano- to supermicron-particles. In addition, flow turbulence and particle condensation/evaporation in lenses will be studied to facilitate design optimization and better understanding of aerosol mass spectrometer measurement uncertainties.

The research aims will be accomplished by a partnership between two institutions in Nevada (i.e., the Desert Research Institute and University of Nevada, Reno) and the Pacific Northwest National Laboratory of the Department of Energy. The project team will first conduct computational fluid dynamics simulations of novel particle-focusing aerodynamic lens and nozzle geometries to explore alternative designs that might improve particle focusing. The transition of flow from laminar to turbulent will be studied by simulations and experiments, which will provide guidance for lens design and operation to prevent particle dispersion by turbulence. The most important contribution of this project will be an improved aerodynamic lens system that can focus a wider particle size range from about 10 nanometers to 2.5 micrometers with the possibility of extending to 10 micrometers. This design will widen the particle size range analyzed by aerosol mass spectrometers, allowing them to study a broad scale of aerosol processes over a more complete size range using the same lens system. The results will benefit all research communities using focused particle beams, including and aerosol mass spectrometer users and others. Such a wide size range lens system will be deployed by Pacific Northwest National Laboratory collaborators to study particle condensation and evaporation as well as secondary organic aerosol formation and aging, during which particle sizes can vary by several orders of magnitude. It will also be used to study climate effects of biological particles, sea salt, and soil particles, where effective focusing of particles larger than one micron is critical.

The improved lenses can be used in several aerosol mass spectrometers hosted at the Department of Energy Environmental Molecular Sciences Laboratory, a user facility focusing on biological and environmental processes. This project will establish a user facility at the Desert Research Institute for aerodynamic lens design, simulation, and testing, which will be beneficial to a larger research community.
Award Recipient(s)
  • Nevada System of Higher Education, Desert Research Institute (PI: Wang, Xiaoliang)