Spatial–temporal development of a plasma sheet in a surface dielectric barrier discharge powered by a step voltage of moderate duration

A surface dielectric barrier discharge (SDBD) exhibits a thin plasma sheet covering a dielectric barrier. Results of the experimental and theoretical studies on the spatial–temporal dynamics of a plasma sheet in a pulsed SDBD are presented. Argon and air were used as plasma-forming gases at pressures of 4 × 104 Pa and 105 Pa, respectively. The SDBD was powered by a single pulse with a relatively long rise time (⩽1 µs) and of moderate pulse duration. The chosen pulse parameters allowed us firstly to diminish the contribution of the displacement current to the total discharge current drastically and secondly to avoid the development of ionization instabilities by changing cardinally the spatial configuration of the plasma sheet. After each pulse, the surface charge on the barrier was thoroughly removed by a grounded soft metallic mesh. Instant discharge images were taken at different phases of the current and voltage waveforms. We revealed that the plasma sheet of a pulsed SDBD expands over a barrier not only at the current rise stage but also at the current decay stage. A theoretical interpretation of the obtained results is given. It is shown that the plasma expansion over the barrier surface is similar to an unsteady and non-linear diffusion process.