Simulation of the Effect of Ion Migration Rate Increase and Fluctuations on Streamer Branching in Insulating Oil

Plasma in liquids is widely used in material processing, aerospace, medicine, and other fields. The study of discharge behavior in liquid dielectrics can reveal the formation mechanism of plasma at the physical level. This article presented a mathematical model that considers ion migration rate increase and electron mobility as well as the random fluctuation characteristic of ion. Our study is completed with finite element analysis (FEA), and theoretically study the inception and propagation of streamers in insulating oil. The results show that the morphology of streamer from the improved equations are consistent with experimental results, effectively presenting the propagation process of streamers at different voltages. The direction of the streamer branches will shift, and new branches appears in the initial branch head in the process of streamer propagation. Besides, the propagation velocity of the branch head is higher than the propagation velocity of the streamer tail. Additionally, the macroscopic size of the streamer is positively correlated with the voltage amplitude, with the highest ion density near the needle tip. This study can provide certain theoretical reference for the safe operation of power equipment.