Characterization of DC driven moderate pressure water vapor glow discharge

Despite significant studies conducted to get insight on the physicochemical processes being influenced due to trace water vapor studies involving high water vapor content is limited, which is critical for developing, and assessing water vapor kinetic models. In this study a dc driven moderate pressure glow discharge operating in 100% water vapor has been characterized. The experiments are conducted at 12 Torr with an interelectrode separation of 4 cm. Degassed, deionized water is introduced at 298K preventing any possible condensation of water vapor in the system. VI characteristics of a water vapor plasma is measured over a broad current range. The measurements show that a normal glow is established at ~8 mA having a current density of 6.32 mA/cm² and discharge voltage of 850V. The voltage along the interelectrode separation is measured to determine the electric field in the cathode fall and the positive column. Optical emission spectrometry is performed to determine the gas temperature as well as the presence of key excited and dissociated species. Finally, experiments are also conducted for an air plasma at 12 torr and the characteristics are compared against the water vapor discharge.