Modeling and Analysis of Micro-plasma Bubbles with Electric Field Concentration^*

Plasma generated in liquids has attracted attention as a high-speed reaction field in the fields of surface modification, material synthesis, and water purification. In particular, electrically generated plasma is used for the synthesis of metal/metal oxides by inducing electrochemical reactions through the plasma. We have previously proposed a metal deposition method using plasma-induced bubbles, which can be generated on demand by applying a voltage pulse. However, the mechanism of their generation has not been clarified, and a design theory for device design has not been established. Here, we discuss a method for the on-demand generation of microplasma bubbles by electric field concentration. In this paper, we aimed to construct a finite element analysis model for device design. The validity of the analytical model was confirmed by comparison with experiments. Specifically, we focused on the location of bubble generation, response speed, and density change. As a result, the analytical model was able to reproduce the position of bubble generation, response speed, and density change during pulse application. It was also found that under most conditions, the bubble generation was due to heat. Therefore, by using a model that considers only heat, it is possible to construct a design model with a low computational cost.