Generation and mechanism research of two-dimensional dielectric barrier uniform discharge in open air

In this paper, a linear electrode device is designed to obtain a two-dimensional uniform argon dielectric barrier discharge (DBD) in open air. The effects of applied voltage amplitude, gap width, and pulse repetition frequency on the discharge uniformity are investigated. It is found that uniform discharge can be generated within a certain voltage range. Gap width is a crucial factor influencing the uniformity of argon DBD. When the gap width is less than 2.5 mm, the discharge is filamentary mode. When the gap width increases, the filamentary discharge turns to uniform discharge. In the uniform discharge mode, the intensity of the discharge increases as the pulse repetition frequency increases. Due to the difference in reduced electric field E/p and the different wall charge distributions in filamentary and uniform discharges, there is a significant difference between the breakdown times in different discharge modes. Through the short exposure time evolution images taken by a high-speed intensified charge-coupled device (ICCD) camera combined with theoretical analysis, the mechanism of this uniform discharge formation is investigated. The results show that the discharge develops uniformly in the radial direction. The discharge starts from Townsend discharge, and the subsequent development of the discharge differs from both the traditional glow discharge and the Townsend discharge. This is due to the combined effect space charges and electric field. The most intense of electron collision ionization is generating near the middle of the gap. The most intense portion of the light intensity is always located in the middle of the gap and near the vicinity of the dielectric plate. The variation of plasma parameters with discharge parameters is studied using spectral diagnostics. In uniform discharge, ne and Te grow simultaneously with increasing voltage. The formation of uniform discharge is related to the combined action of the nanosecond pulsed power supply, the dielectric plate with adhering spheres, and the airflow. The results of the study provide theoretical and experimental data support for applications.