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In negative corona discharges in ambient air different discharge modes can be observed. In this paper the discharge current regions corresponding to these modes are determined. The influence of anode geometry, anode resistivity, inter-electrode distance and gas flow on the threshold currents that mark the corona-to-glow and glow-to-spark transitions is investigated. The experimental data are backed up by an analytical treatment of ionization instability development within a local current spot on metallic and resistive anodes.

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The aim of this work is to develop barrier coatings by using an atmospheric pressure dielectric barrier discharge (DBD). For this purpose the plasma polymers obtained from a hybrid organic–inorganic precursor compound as well as from a purely organic compound were compared. The physical properties of the coatings were determined by scanning electron microscopy and scanning probe microscopy analysis as well as by profilometry and by determining their oxygen transmission rates. The chemical structure was revealed by ATR-FTIR analysis and 13C- and 29Si-CP/MAS solid-state nuclear magnetic resonance measurements. It is shown that atmospheric pressure plasma polymerization of hybrid polymer precursors leads to coatings with excellent barrier properties due to the unique synergistic effect of the organic and the inorganic network structures that are formed in the plasma.