Public Abstract

DE-SC0018202: Collaborative Research: Understanding Nanoparticle-Plasma Interactions in Dusty Non-Thermal Plasmas by Nanoparticle Probes and Online Aerosol Characterization

Award Status: Inactive

Institution: Regents of the University of Minnesota, Minneapolis, MN
UEI: KABJZBBJ4B54
DUNS: 555917996

Most Recent Award Date: 06/13/2019
Number of Support Periods: 3
PM: Podder, Nirmol

Current Budget Period: 08/01/2019 - 07/31/2020
Current Project Period: 08/01/2017 - 07/31/2020
PI: Hogan, Christopher

Supplement Budget Period: N/A

Public Abstract

Non-thermal dusty plasmas are complex, non-equilibrium systems in which nanometer-sized particles of condensed phases interact with electrons, ions, and neutral species of disparate temperatures (i.e. electrons are significantly hotter than the other species). These systems exist both undesirably, as in the case of chemical vapor deposition (CVD) processes where dust particles are a source of contamination, and for technological purposes to produce nanoparticles for a wide range of emerging applications. An important but relatively unexamined feature of nanoparticle-laden, non-thermal dusty plasmas is that the temperatures of nanoparticles are size dependent, and converge to neither the neutral gas nor electron temperatures. Ultimately, it is the temperature of a nanoparticle which determines whether it is stable or will evaporate, as well its crystallinity; thus, thermal energy transfer is a critical issue for both dust particle mitigation and controlled nanoparticle synthesis. Previous experiments have studied plasmas where nanoparticles are spatiotemporally nucleating and growing from a vapor precursor which makes it difficult to reveal size-dependent behavior. This proposed research is focused on controlled experiments based on the introduction of pre-made, size-focused nanoparticles into a plasma of well-defined residence time, combined with on line measurements of the extent of evaporation, crystallization, and surface growth, which will uniquely determine the nanoparticle temperature in the plasma. Further, as the energy balance for a nanoparticle in a plasma is influenced by particle-ion, particle-electron, and particle-neutral collisions, measurements will provide key insights into collision rates for nanoparticles in atmospheric pressure plasmas, which occur in an intermediate regime of collisionality. The results of the proposed experiments will not only lead to improved understand of dusty plasma systems, but will also have important consequences in the application of plasmas in materials processing. An understanding of thermal energy transfer to particles in plasmas will enable improved design of plasma reactors used in chemical vapor deposition, as well as nanocrystal synthesis. In addition, the proposed research is highly interdisciplinary, combining state-of-the-art aerosol measurements with atmospheric pressure plasma diagnostics to investigate dusty plasma behavior.

Non-thermal dusty plasmas are complex, non-equilibrium systems in which nanometer-sized particles of condensed phases interact with electrons, ions, and neutral species of disparate temperatures (i.e. electrons are significantly hotter than the other species). These systems exist both undesirably, as in the case of chemical vapor deposition (CVD) processes where dust particles are a source of contamination, and for technological purposes to produce nanoparticles for a wide range of emerging applications. An important but relatively unexamined feature of nanoparticle-laden, non-thermal dusty plasmas is that the temperatures of nanoparticles are size dependent, and converge to neither the neutral gas nor electron temperatures. Ultimately, it is the temperature of a nanoparticle which determines whether it is stable or will evaporate, as well its crystallinity; thus, thermal energy transfer is a critical issue for both dust particle mitigation and controlled nanoparticle synthesis. Previous experiments have studied plasmas where nanoparticles are spatiotemporally nucleating and growing from a vapor precursor which makes it difficult to reveal size-dependent behavior. This proposed research is focused on controlled experiments based on the introduction of pre-made, size-focused nanoparticles into a plasma of well-defined residence time, combined with on line measurements of the extent of evaporation, crystallization, and surface growth, which will uniquely determine the nanoparticle temperature in the plasma. Further, as the energy balance for a nanoparticle in a plasma is influenced by particle-ion, particle-electron, and particle-neutral collisions, measurements will provide key insights into collision rates for nanoparticles in atmospheric pressure plasmas, which occur in an intermediate regime of collisionality.

The results of the proposed experiments will not only lead to improved understand of dusty plasma systems, but will also have important consequences in the application of plasmas in materials processing. An understanding of thermal energy transfer to particles in plasmas will enable improved design of plasma reactors used in chemical vapor deposition, as well as nanocrystal synthesis. In addition, the proposed research is highly interdisciplinary, combining state-of-the-art aerosol measurements with atmospheric pressure plasma diagnostics to investigate dusty plasma behavior.