A streamer discharge model is developed to analyse the characteristics of a pulsed positive streamer discharge in point-to-plane electrodes filled with oxygen–nitrogen mixed gas at room temperature and atmospheric pressure. In this paper we study the mechanisms of O and N radical production in an atmospheric-pressure streamer discharge. To confirm the validity of the simulation model, the discharge emission of light and the discharge current are compared with experimental data at several voltages in gas mixtures with 2–20% oxygen concentrations. The calculated streak picture and the axial distribution of streamer luminous intensity are in good agreement with our previous experimental results. After demonstrating the reliability of the model, we performed a numerical study on radical production by the streamer discharge. The experimentally obtained axial distributions of oxygen radical production in O₂(20%)/N₂ and nitrogen radical production in O₂(2%)/N₂ are successfully reproduced in our simulation. For the production of nitrogen radicals, two-step dissociation through the vibrationally excited states is predominant.

Electrohydrodynamic (EHD) force is used for active control of fluid motion and for the generation of propulsive thrust by inducing ionic wind with no moving parts. We propose a method of successively generating and accelerating ionic wind induced by surface dielectric-barrier-discharge (DBD), referred to as a DBD plasma actuator with multiple electrodes. A conventional method fails to generate unidirectional ionic wind, due to the generation of a counter ionic-wind with the multiple electrodes DBD plasma actuator. However, unidirectional ionic wind can be obtained by designing an applied voltage waveform and electrode arrangement suitable for the unidirectional EHD force generation. Our results demonstrate that mutually enhanced EHD force is generated by using the multiple electrodes without generating counter ionic-wind and highlights the importance of controlling the dielectric surface charge to generate the strong ionic wind. The proposed method can induce strong ionic wind without a high-voltage power supply, which is typically expensive and heavy, and is suitable for equipping small unmanned aerial vehicles with a DBD plasma actuator for a drastic improvement in the aerodynamic performance.

Axisymmetric two-dimensional (2D) simulation is often used in case of streamer discharge in atmospheric-pressure air. To validate the 2D simulation of streamer discharge, the simulation has to be compared with the measurement results. However, there is difficulty in performing the comparison because the streamer is not a 2D phenomenon but a three-dimensional phenomenon. In this study, a pseudo-2D axisymmetric single-filament pulsed positive streamer discharge was generated in atmospheric-pressure air and compared with our 2D simulation. The propagation, emission intensity, shape, and cathode current of the streamer were compared. The ozone density was also measured using laser spectroscopy and compared with the simulation because our simulation intends to simulate the dynamics of reactive species. The measurements and simulations exhibited some agreements and disagreements. The measurement also showed a cathode fall and other cathode phenomena, which were not considered in the simulation.