Hannover 2016 – scientific programme

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P: Fachverband Plasmaphysik

P 20: Poster Session- Low Temperature Plasmas

P 20.25: Poster

Wednesday, March 2, 2016, 16:30–19:00, Empore Lichthof

Surface charge measurements on transparent dielectrics in diffuse and filamentary barrier discharges — •Robert Tschiersch¹, Marc Bogaczyk², Sebastian Nemschokmichal¹, and Jürgen Meichsner¹ — ¹Institute of Physics, University of Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald, Germany — ²Leibniz Institute for Plasma Science and Technology, Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany

This work reports on the realization of surface charge measurements on dielectrics which are frequently used in barrier discharge (BD) configurations. The surface charge was measured spatially and temporally resolved via the electro-optic Pockels effect of Bi₁₂SiO₂₀ (BSO). The innovative feature consists in covering the BSO crystal with optically transparent dielectrics, such as float glass (based on SiO₂), mono-crystalline alumina (Al₂O₃), and magnesia (MgO). The dynamics and the spatial distribution of negative and positive surface charges were studied in diffuse and filamentary BDs operated in helium with variable admixture of nitrogen at elevated gas pressures. In particular, the amount of transported charge is compared with the amount of deposited surface charge. Moreover, the lateral distribution of separated surface charge spots is determined, which mark the footprints of filamentary breakdown channels. As the previously reported surface charge diagnostic was specific for a BSO surface exposed to the plasma, the present work achieves a more generalizable level making this powerful method accessible to various transparent dielectrics.