Regular Article

Discharge propagation on a dielectric surface in a single-filament arrangement

¹ Leibniz Institute for Plasma Science and Technology, Felix-Hausdorff-Str. 2, 17489 Greifswald, Germany
² Formerly at University of Greifswald, Institute of Physics, Felix-Hausdorff-Str. 6, 17489 Greifswald, Germany
³ University of Rostock, Institute of Physics, Albert-Einstein-Str. 23–24, 18059 Rostock, Germany

^a e-mail: kettlitz@inp-greifswald.de

Received: 14 February 2020
Received in final form: 31 March 2020
Published online: 9 June 2020

Abstract

Discharge development and streamer propagation on a dielectric surface were investigated in nitrogen-oxygen gas mixtures at atmospheric pressure. A coaxial pin-to-pin arrangement was used to generate single surface discharges driven by positive unipolar square wave high voltages of between 7 and 9 kV at 4.3 kHz. The development of surface discharges was recorded by ICCD and streak cameras. The discharges developed on the surface using pin electrodes attached directly to the dielectric plate. The accumulation over several discharge events showed a propagation front evolving from the electrode tip, while images of single discharges showed a non-uniform and branched structure of discharge channels. The electrode polarity influenced the discharge expansion and propagation velocity. Positive polarity of the metallic electrode (rising slope of HV pulses) led to a cathode-directed streamer with higher propagation velocities (5 × 10⁵ m/s) than for negative polarity (relative to surface charges; falling slope). The increase in the O₂ content in N₂ from 0.1 to 20 vol% resulted in a decrease in discharge duration and an increase in streamer velocities.