Issue 23, 2023

Experimental and computational investigation into the hydrodynamics and chemical dynamics of laser ablation aluminum plasmas

Abstract

Laser ablation plasma chemistry is governed by a complex interplay between hydrodynamic plasma-gas mixing processes, thermodynamics, and rapid high-temperature chemical reactions. In this work, we investigate the gas-phase oxidation chemistry of ns-laser ablation aluminum plasmas in air using optical spectroscopy combined with advanced multi-physics modeling. Experimental measurements demonstrate the formation of AlO in the plasma plume as early as 1 μs while computational results reveal that several AlxOy species are distributed in the periphery of the plume at even earlier times (<20 ns) in the presence of large temperature gradients and strong shockwaves. Interactions with the ablation crater during rapid plume expansion are shown to initiate vortex formation, followed by mixing dynamics that work to pull AlO into the vortices to react with gas-phase Al to form Al2O. Oxygen and several aluminum oxides are simultaneously pulled up through the stem of the fireball, encouraging further intermixing between reacting species and enhanced molecular formation. This work concludes that chemical dynamics in laser ablation plasmas is driven by diffusion processes, concentration gradients, and plume hydrodynamics while strong shockwaves generated during laser ablation do not impede chemical reactions.

Graphical abstract: Experimental and computational investigation into the hydrodynamics and chemical dynamics of laser ablation aluminum plasmas

Supplementary files

Article information

Article type
Paper
Submitted
06 Apr 2023
Accepted
20 May 2023
First published
31 May 2023

Phys. Chem. Chem. Phys., 2023,25, 15666-15675

Author version available

Experimental and computational investigation into the hydrodynamics and chemical dynamics of laser ablation aluminum plasmas

E. H. Kwapis, J. W. Posey, E. Medici, K. Berg, R. W. Houim and K. C. Hartig, Phys. Chem. Chem. Phys., 2023, 25, 15666 DOI: 10.1039/D3CP01586F

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