Microdischarge Species Evolution in a 2-Dimensional Packed Bed Reactor

Packed bed reactor discharges are beinginvestigated for a wide range of applications such as ozone generation, dryreforming of methane, plasma catalysis, and plasma-aided combustion. Plasma formation in packed bed reactors takes the form of microdischarges that occur on the surfaces and in the pores of the aggregate. Such microdischarge formation and propagation in porous media are not well understood. To elucidate physical and kinetic mechanisms underlying the propagation of plasma through interconnected pores, we are investigating plasma formation at atmospheric pressure through a 2-dimensional (2-d) porous media. A 2-d array of dielectric aggregate of varying dielectric constants is used to simulate and visualize plasma formation between dielectric particles. The 2-d geometry allows for the direct observation of discharge propagation and species formation using fast cameras and emission spectroscopy, thereby eliminating intervening layers that would otherwise obstruct line of sight observation. The discharge is excited using AC voltage typical of packed bed dielectric barrier discharges (DBDs) as well as repetitively pulsed, ns high voltage pulses. Spatial distributions of experimentally measured plasma-generated radicals are compared with predictions of computational models with the goal of model validation insights into systems with higher dimensionality.