Physico-chemical characterization of a surface barrier discharge plasma source

Cold Atmospheric pressure Plasmas (CAP) generated by Dielectric Barrier Discharges (DBDs) are being studied and developed for an ever-widening range of applications in both biomedical and industrial areas. In particular surface DBDs (SDBDs), consisting of a planar powered electrode separated from a grounded mesh by a thin dielectric layer, have been gaining great interest for their ability to produce highly reactive atmospheres at close-to-environmental temperature and almost independent from the electrical properties of the target, which is treated in the afterglow of the surface plasma. The active chemistry initiated in the afterglow of SDBDs operated in air is characterized by the presence of long-lived reactive oxygen and nitrogen species such as O3, NOx and HNOx, which are recognized to play an important role in many industrial and biomedical applications based on the use of the plasma afterglow. Knowing the kinetics of all the chemical species produced in the plasma and in its afterglow is then fundamental to control and optimize the processes for which SDBDs are being used. This project focuses on the physico-chemical characterization of a SDBD plasma source developed by the research group in Industrial Application of Plasmas (AIP - DIN - Alma Mater Studiorum), supplied with a high voltage AC generator with tunable frequency and duty cycle. First a study of the surface power density (SPD) variation as a function of voltage, frequency and duty cycle was made. Then the kinetics of O3/NO2/NO3 concentrations in the plasma afterglow were studied by means of OAS measurements. This project’s main aim is to gather additional knowledge on the kinetics of the produced reactive species, comparing the results with the ones from other works from literature, providing additional evidence about SPD being the driving parameter for plasma afteglow kinetics. A second aim is to provide a set of data that can be used as input and validation for future modelling tools.