Radio-Frequency-Driven Atmospheric-Pressure Plasmas in Contact with Liquid Water

Abstract
Atmospheric-pressure plasmas were produced on the surface of liquid water by radio-frequency (RF) power supply. A quartz chamber with an off-center inner electrode was used to generate discharges with a wide range of filling gas pressures. When the chamber was filled with fuel gas and liquid water and a sufficient RF power was supplied to the system, plasmas were observed to be produced around the inner electrode as well as on the water surface. Optical emission spectroscopy (OES) identified the generation of oxidative hydroxyl (OH) radicals and decoloration of methylene blue in the solution demonstrated oxidative capacity of water plasmas generated in this system.