Filamentary and Homogeneous Modes of Dielectric Barrier Discharge (DBD) in Air: Investigation through Plasma Characterization and Simulation of Surface Irradiation Priyadarshini Rajasekaran, Philipp Mertmann, Nikita Bibinov, Dirk Wandke, Wolfgang Vio ¨l, Peter Awakowicz* Full Paper P. Awakowicz, P. Rajasekaran, P. Mertmann, N. Bibinov Institute for Electrical Engineering and Plasma Technology, Ruhr-Universitaet Bochum, Universitaetsstr. 150, 44801 Bochum, Germany Fax: (þ0049) 234 32 14230; E-mail: awakowicz@aept.rub.de D. Wandke CINOGY GmbH, Max-Naeder-Str. 15, 37114 Duderstadt, Germany W.Vio¨l Faculty of Natural Sciences and Technology, University of Applied Sciences and Arts, Von-Ossietzky-Str. 99, 37085 Goettingen, Germany W.Vio¨l Laser Laboratory Goettingen, Hans-Adolf-Krebs-Weg. 1, 37077 Goettingen, Germany The reported dielectric barrier discharge (DBD) source comprises of a ceramic-covered copper electrode, and plasma can be ignited in ambient air with grounded ‘opposite’ electrodes or with objects of high capacitance (e.g., human body), when breakdown conditions are satisfied. Filamentary plasma mode is observed when the same source is operated using grounded opposite electrodes like aluminium plate and phosphate buffered saline solution, and a homogeneous plasma mode when operated on glass. When the source is applied on human body, both homogeneous and filamentary discharges occur simultaneously which cannot be resolved into two separate discharges. Here, we report the characterization of filamentary and homogeneous modes of DBD plasma source using the above mentioned grounded electrodes, by applying optical emission spectroscopy, microphotography and numerical simulation. Averaged plasma parameters like electron velocity distribution function and electron density are determined. Fluxes of nitric oxide, ozone and photons reaching the treated surface are simulated. These fluxes obtained in different discharge modes namely, single-filamentary discharge (discharge ignited in same position), stochastical filamentary discharge and homo- geneous discharge are compared to identify their applications in human skin treatment. It is con- cluded that the fluxes of photons and chemically- active particles in the single filamentary mode are the highest but the treated surface area is very small. For treating larger area, the homogeneous DBD is more effective than stochastical filamen- tary discharge. -7.5 -5.0 -2.5 0.0 2.5 5.0 7.5 1E16 1E18 1E20 1E22 Flux of ozone / m -2 s -1 radius of electrode / mm 1 ppm single-filamentary DBD homogeneous DBD stochastic-filamentary DBD Plasma Process. Polym. 2010, 7, 665–675 ß 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/ppap.200900175 665