Dielectric barrier discharges in atmospheric pressure helium in cylinder-plane geometry: experiments and model

The discharge behaviour of metallic cylinder-dielectric plane gaps in flowing helium was examined under atmospheric pressure at a frequency of 10 kHz as a function of gap length and applied voltage. The high-voltage electrode consisted of a steel cylinder with a radius of 3.15 mm, with alumina (Al2O3) or glass plates being utilized as low-potential electrodes. The bottom surface of the low-potential electrodes was covered with a thin Al layer (alumina plate) or an ITO layer (glass plate) that formed the grounded counter-electrodes. The electrical and photoemission currents were recorded simultaneously and precisely synchronized with an ultra-high-speed intensified charge coupled device camera for recording the discharge patterns. The experimental results were compared with those derived from a mathematical model on the basis of the continuity equations for electrons, ions and excited particles and the Poisson equation. The influence of surface charge on the dielectric electrodes on the time evolution of the helium discharge was analysed, and the experimental and theoretical vertical (y(t)) and horizontal (x(t)) dimensions of the discharges were determined for different low-potential electrode arrangements. A reasonable agreement was obtained between the measured and calculated y(t) and x(t) values.