Characteristics of short-gap pin-to-pin discharge flow field based on schlieren technique

Gas discharge technology is widely applied in the field of aerospace, materials, medical treatment, agriculture etc. Its distinctive feature is the ability to generate visible plasma. However, some nonluminous processes in short-gap air discharge, such as changes in the flow field during discharge, cannot be observed by traditional optical photography techniques. Consequently, the processes or mechanisms underlying gas discharge remain incompletely understood. In this study, Schlieren technique combined with the high-speed camera was used to study the flow field of short-gap pin-pin discharge. The schlieren results show that when corona discharge occurs, a slender jet channel containing a large number of charged particles will be ejected from the tip of both electrodes, but the velocity of the anode jet is generally higher than that of the cathode jet, and the jet channel fluctuates slightly around the axis, causing a certain degree of disturbance in the surrounding flow field. The higher the applied voltage level, the faster the jet velocity, the more obvious the channel and the more severe the disturbance of the flow field around the electrode. Moreover, it is also found that the trajectory of the jet channel and the spark channel partially or completely overlap, which indicates that the jet channel generated by corona discharge will guide the formation of the spark channel, and there is a certain internal relationship between the two. It is helpful for us to understand more deeply the microscopic mechanism and the essential principle of discharge phenomenon.