Generation and transport of liquid-phase reactive species due to plasma-liquid interaction

Abstract

Medical applications of atmospheric-pressure plasmas (APP s) in ambient air at room temperature have been widely studied because of APPs' ability to provide reactive oxygen / nitro gen species (RONS) to living tissues. Although the effectiveness of plasma-based therapies for some types of medical treatments has been widely reported, it has not been clear yet how such plasmas interact with living cells and tissues and what specific chemical spices contribute to the observed therapeutic effects. In an attempt to address such questions, we have performed numerical simulations of chemical reactions and transport of reactive species in liquid exposed to a low-temperature APP. The governing equations that we have employed for this study are reaction-diffusion-advection equations coupled with Poisson equation. For the sake of simplicity, we only consider pure water as the solvent. The rate constants, mobilities, and diffusion coefficients are obtained from the literature. The gaseous species are given as boundary conditions and time evolution of the concentrations of these chemical species in pure water is solved numerically as functions of the depth in o ne dimension. In addition to the case where the water surface is irradiated by a plasma, we have also experimentally examined the case where a plasma is generated in water by nano-second high voltage discharges. The results of both numerical simulations and discharge experiments will be presented.