Characterization of the evolution of underwater DBD plasma jet

An air plasma jet formed underwater using a coaxial DBD electrode configuration with gas flow is being studied for water treatment applications.The arc-like behavior of the discharge in the absence of any obvious return electrode is not well understood.This study seeks to understand the underlying nature of the arc-like jet mode by studying the evolution of the discharge from microdischarge to jet mode.Photographic and spectroscopic data are used to develop a phenomenological model of discharge evolution.Time-averaged spectra were used to assign an average plume and electron temperature.Calculated jet temperatures were consistent with observed affects such as melting and oxide layer formation on a downstream substrate.The capacity of the microdischarge mode to decompose organic dye in water as a function of time, confirmed previously in the jet mode, was also demonstrated in the absence of the jet.