DOE Center for Control of Plasma Kinetics Highlight Investigating the plasma-liquid interface using a 2-D bubble in a modified Hele-Shaw cell: First results

The interaction of plasmas with liquid water is the basis of a number of new and exciting technologies. These technologies range from novel water purification methods to non-equilibrium chemical processing and plasma medicine. At the heart of the plasma-liquid interaction is the in-terface. Key physical processes that ultimately “activate ” the liquid are believed to occur at this interface. The discharge plasma subjects the interface to energetic particle bombardment, UV ra-diation, locally high electric fields, electrolysis, and high temperature gradients. Indeed, it is this interaction that creates an active boundary layer. The active boundary layer itself is conjectured to be a thin region adjacent to the plasma-liquid interface that acts as a transfer vehicle—imparting energy and information from the plasma to the surrounding liquid. The key question is how do the physical processes occurring in this boundary layer give rise to large-scale changes in the bulk liquid. Physical processes known to occur at the interface and boundary layer include the produc-tion of radicals, species transfer, evaporation, fluid dynamical instabilities and gas-liquid mixing. Quantifying these processes is key to understanding the interplay between the plasma kinetics in the gas phase incident on the interface and the resulting multiphase processes occurring in the boundary layer and beyond