Investigation of Thermodynamic Conditions in an Arc Discharge Plasma

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The goal of this study is to improve our understanding of the basic physics of arc discharge plasmas. Plasma, often called the fourth state of matter, is an ionized gas that is present in almost every aspect of everyday life; and an electric arc discharge is one of the most basic plasma phenomena that are used in industry and observed in nature. Examples of electric arcs include lightning, spark plugs for combustion, plasma torches, arcjet facilities for supersonic and hypersonic flows, and devices for nanomaterials synthesis. Depending on the conditions of their generation and maintenance, arc discharge plasmas have a wide range of properties and parameters, many of which remain poorly understood. This study will be performed using both numerical simulations and state-of-the-art laser diagnostics to expand the understanding of arc discharges. Training the next generation of plasma scientists and engineers will be provided through this project while awareness about plasma technologies and its importance will be raised to local K-12 students.Despite its long history, the conditions for local thermodynamic equilibrium (LTE) in atmospheric pressure arc discharges are poorly understood due to limited experimental measurements of plasmas in thermal equilibrium. Conventional probes and optical measurements pose significant challenges since the arc core is a high temperature environment with high intensity of radiation. The focus of this project is to investigate the validity of the LTE assumption in an arc discharge operating in atmospheric pressure. Specifically, the research objectives are to: (i) develop a multidimensional nonequilibrium plasma model of a non-ablating nitrogen arc plasma coupled with a radiative heat transfer model; (ii) establish theory and analysis of the Coherent Rayleigh-Brillouin Scattering (CRBS) technique for plasma flows; and (iii) validate the computational results against experiment data, including the translational temperature obtained from CRBS and the vibrational state of nitrogen obtained from Optical Emission Spectroscopy.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.