Fundamental Investigations on the Plasma Chemistry in Dielectric Barrier Discharges Operated with Air-Water Vapor Mixtures at Sub-Atmospheric Pressure

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The project aims at the investigation of the fundamental plasma-chemical reaction mechanisms leading to the controlled generation of reactive oxygen and nitrogen species (RONS) in dielectric barrier discharges (DBD) operating near or at atmospheric pressure with mixtures of argon, air and water vapor. Therefore, a novel type of sub-atmospheric pressure low-temperature dielectric barrier discharge, termed Venturi-Vapor-DBD, is employed. It allows the generation of reactive plasma operating with air/water vapor mixtures in the pressure range from 20 to 1000 mbar and makes it possible to transfer the plasma-generated RONS from a sub-atmospheric pressure discharge zone to atmospheric pressure by means of a Venturi pump. The analysis of the discharge behavior and plasma dynamics will be performed for a large range of discharge parameters using spectroscopic and electrical measurements in combination with numerical modeling. The investigations will provide a detailed understanding of the prerequisites and underlying reaction mechanisms leading to a stable and reproducible operation of Venturi-Vapor-DBDs. Furthermore, they will make basic information available on the impact of the operating parameters and gas mixtures used on the operating regime, the plasma dynamics and the plasma composition with the focus on ozone, nitrogen oxides and the water-based species nitrous acid and hydrogen peroxide. In particular, those operating conditions are to be determined at which an ozone-dominated, a nitrogen oxide-dominated and a hydrogen peroxide-dominated, respectively, plasma chemistry occurs.