Simulation of the chemistry induced in air by a dielectric barrier discharge plasma source and experimental validation using optical absorption spectroscopy

The dielectric barrier discharge consists in a plasma discharge developed in the volume between two metal electrodes covered by a dielectric material. DBDs setup are remarkably good and cheap tools to generate non-equilibrium plasmas at atmospheric pressure, characterized by highly energetic electrons in a background gas whose temperature is close to room temperature. The produced non-thermal plasma represents an environment where extremely energetic chemical processes can occur at low/medium temperatures, making them suitable for biomedical applications. Among the biomedical applications of DBD sources, this thesis concerns bacterial decontamination, focusing on the chemical/physical characterization of plasma. The antimicrobial efficacy of the plasma treatment is connected with the chemical-physical species that plasma is able to generate in air, such as reactive oxygen and nitrogen species (RONS). In order to achieve an optimal bacterial reduction, it is necessary to optimize the production of RONS species. The study of plasma-induced chemistry is very complex due to the multitude of physical states that characterizes the plasma and due to the extremely fast kinetics of the species involved in the plasma-assisted reactions. Consequently, a computational modelling of the plasma is indispensable to understand all the chemical phenomena induced simultaneously by plasma during the treatment. A fluid method implemented in PLASIMO was chosen to simulate the plasma; which was developed at the Eindhoven University of Technology. During my thesis project, I spent a few months at the Eindhoven University of Technology where I performed several simulations on the chemistry induced by a DBD plasma source in air. The results of the simulations have been experimentally validated in the Raizer Plasma Diagnostic Lab at the University of Bologna via optical absorption spectroscopy, which allows to characterize the gas-phase chemistry of the plasma via Lambert-Beer law.