Target interacting with an atmosheric pressure helium DBD

Summary form only given. In last decades, atmospheric pressure plasma jets (APPJs) have been extensively studied due to their potential in applications for biomedical treatment or analytical chemistry. However, the use of plasma jets for technical applications requires extensive understanding of the processes that take place in realistic conditions of the use1.Numerous parameters such as the geometry of the device, the power supply or the working gas have been identified as having an influence on the plasma characteristics. Recently it has been reported that one of the main factors that affect the behavior of the plasma discharge is the surface placed in front of the jet2. The aim of this study is to investigate on the effect of the target conductivity on the discharge characteristics. The plasma source used in this work has an asymmetric design and is composed of two cylindrical dielectric parts - a cylindrical dielectric chamber ending by a dielectric tube with a smaller diameter. An external conductive electrode surrounds the two parts. The source is operated with helium at a flow of 2.1 l/min and powered by 20 kHz sinus or square voltage of 2 kV. The plasma propagation for this plasma source was described and analyzed without target - i.e. free plasma jet3. In this work, the influence of several targets (copper, alumina, water and polymer) on the spatial distribution of several excited or ionized species from the APPJ (N2, N2+, He, O) was studied. Resolved spatial optical emission distribution measurements were performed with an ocean optics spectrometer HR2000+. Time resolved plasma jet propagation was studied with an ICCD camera. Parametric studies for sinus and square waveforms and several distances between the target and source will be presented.