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Corona discharge is extensively researched due to the wide applications in the fields of electrostatic precipitator, flow control, thermal management, and so on. Previous researches observe that the characteristics of the corona discharge, such as the average current in the Trichel pulse regime, could be influenced by the airflow velocity. In this paper, the effect of the airflow rate on the corona discharge is further investigated by using a needle-mesh discharge structure. The experimental results show that the discharge is transferred from a large amplitude, long pulse interval time condition to a small amplitude, short interval time condition when increasing the airflow rate and, at the same time, the discharge region is shrunk toward the centerline of tube channel (i.e., shrinking regime). However, after a stable regime around a certain airflow rate, the above-mentioned parameters are changed toward the opposite direction and the discharge region is expanded, when further increasing the airflow rate (i.e., expanding regime). This nonmonotonous phenomenon has not been observed in literature before, and we further investigate it under different tube channel diameters. It is found that, under a larger tube channel diameter, the transition point (corresponding to the minimum pulse amplitude and interval time) moves toward a larger gas flow rate. The physical mechanisms for this phenomenon are analyzed by considering the transport effect by airflow under different Reynolds numbers. It can be caused by a comprehensive effect of the mass transfer, heat transfer, movement process of particles, and frictional loss in the discharge space. The phenomenon revealed in this paper is possibly utilized to improve the application of corona discharge under airflow. [ABSTRACT FROM AUTHOR]

The dielectric-barrier discharges (DBDs) under airflow have been widely used in the fields of airflow control, plasma-assisted combustion, and surface modification. Our previous work demonstrates that the discharge intensity under airflows could be adjusted by a discharge configuration with upstream and downstream electrodes. In this paper, a further investigation of discharges under airflows is processed with a multicathode DBD configuration. With the injection of airflows to the discharge region, the first upstream region produces a decrement of discharge intensity, while the following downstream region always provides greater discharge intensity than that of the adjacent upstream discharge region. An optimal discharge configuration is found by appropriately selecting the distances between the cathodes, wherein the last downstream region can produce maximum discharge intensity. The mechanisms are analyzed by considering the transport effect of airflows and the lifetime of charged and metastable particles. The charged and metastable particles are transported to the downstream region, and these particles always act as the responsible seeds to enhance the downstream discharges. In addition, due to the limited lifetime of charged and metastable particles, the enhancement effect may be weakened under long transport distances. Finally, potential applications for multicathode DBDs are also provided. [ABSTRACT FROM AUTHOR]