Effects of current limitation through the dielectric in atmospheric pressure glows in helium

Abstract

The influence of the dielectric barrier on the discharge regime of a uniform atmospheric pressure glow discharge is studied through fast, time-resolved imaging of the discharge optical emission and by a one-dimensional fluid model. The experiments show that the discharge regime can be adjusted over a wide range from a glow-like regime with a pronounced Faraday dark space and positive column to a Townsend-like discharge regime in which those features are absent. The determining factor for the discharge regime is the current limitation through the dielectric. Results of the one-dimensional fluid model confirm this observation. The fluid model also indicates that metastable helium atoms generated during a discharge pulse contribute significantly to the pre-ionization of the gas before the next breakdown through Penning ionization of nitrogen impurities.

Complex dynamic behaviors of nonequilibrium atmospheric dielectric-barrier discharges

“…The gas gap between the two dielectrically insulated electrodes was fixed at 2 mm, and the two dielectric layers were identical with each other having a thickness of 1 mm and a relative permittivity of 7.6. The secondary electron emission coefficient ␥ was set to 0.02, whereas drift coefficients as well as reaction rate constants were taken from a recent DBD simulation study 30 and the corresponding diffusion coefficients can be obtained by Einstein's relation.…”

Collective phenomena in volume and surface barrier discharges

“…Also the appearance of a multitude of short current pulses per half cycle observed when the voltage is raised could be explained by modelling [48]. By varying the thickness of the dielectric Mangolini et al could demonstrate its current limiting properties [49]. A thicker dielectric reduces the observed current peak and shifts the operating point along the subnormal branch of the current voltage characteristic from a glow-like towards a more Townsend-like appearance.…”

The influence of impurities on the performance of the dielectric barrier discharge

“…It is described using nine different species and 18 different chemical reactions which have previously been reported. 5 The experimental setup under study is exactly the same as the one used by Mangolini et al 6 It is a dielectric barrier discharge with both electrodes covered with an alumina dielectric ͑⑀ r =9͒ of 1 mm thickness. The spacing between the dielectric surfaces is 5 mm and on the top electrode a sinusoidal voltage is applied while the bottom electrode is grounded.…”

“…In order to first validate our model an electric potential is applied on the powered electrode with a frequency of 10 kHz and an amplitude of 2 kV which is exactly the same as used by Mangolini et al 6 In order to stay consistent with their research we used an impurity of 100 ppm of N 2 , as they estimated from their setup analysis. In Fig.…”