Study of large-area atmospheric pressure plasma jet based on coplanar dielectric barrier discharge

In order to obtain a uniform large-area plasma jet at the atmospheric pressure, a new structure of coplanar dielectric barrier discharge (DBD) is proposed in this paper. The structure used in large-area DBD plasma jet consists of two coaxial annular dielectric tubes, and an alternating current electric field is applied by metal film electrodes outside the tubes to form dielectric barrier discharge in the air gap. Based on this configuration, a uniform annular jet is achieved, with diameter of 12 mm and thickness of 2-3 mm. The discharge characteristics of the proposed structure and the development process of plasma jet are studied. The spectra of the discharge, the electron temperature, the electron density, and the discharge waveforms are diagnosed. The results show that the physical characteristics of the large-area jet obtained in this work are basically the same as that of the traditional small-diameter DBD jet. It is considered that the physical mechanism of the large-area jet propagation is the mutual coupling propulsion process of a large number of positive corona discharges. The influence of electrode structure and air gap structure on the characteristics of the largearea DBD plasma jet is further studied by experiments, and the optimization principle of the large-area DBD plasma jet is proposed.