Gas flow formation by plasma discharge on water surface

Atmospheric plasmas have large potential in many industrial applications including biomedicine because they can produce relevant reactive species for reactions. When atmospheric plasmas are applied to biological samples, these samples are often covered by a liquid layer. It is important to understand the transport of reactive species since the plasma discharge itself also drives a gas flow. In this study, a plasma discharge was produced between a wire electrode and the surface of water by high voltage. This plasma discharge consists of several streamer discharges. The development of a thermal field between the wire electrode and the surface water as well as in the water was observed using the Schlieren visualization technique and a high speed camera. In addition, discharge photos with short exposure time were taken with an image intensifier. A thermal field was found to develop in the gas phase and a circulating flow was formed in the water in the case of low conductivity of 0.8 μS/cm due to the formation of gas flow. Our experiments shows that generation of higher gas velocity could occur with lower conductivity of water.