Inducing discharges in a micrometer catalyst channel by a helium atmospheric pressure plasma jet

Abstract

Discharges in small size pores are important for understanding the interaction effect between discharge and porous materials such as catalysts. In this letter, the discharge behavior in a micrometer channel of a structured catalyst induced by an atmospheric pressure plasma jet (APPJ) is studied using a 2D fluid model. The results show that the APPJ cannot penetrate into a single channel with a radius of 120 μm due to the rapid diffusion loss of electrons to the walls. On the contrary, when the channel is connected to a millimeter cavity in the catalyst, discharges are formed in both the cavity and the channel. Analyses reveal that the strong electric field in the streamer head of the APPJ will propagate across the dielectric layer into the cavity and ignite an electron avalanche therein. Three discharge stages inside the channel can be identified as the negative streamer, the counter-propagating discharges, and the glow-like discharge. The dynamics and mechanisms of discharges are discussed. Our work provides physical insights into generating discharges in mesoscale catalyst pores and may further help develop a promising means for catalyst preparations.