Publications

The impact of carbon dioxide and water on single-pulse nanosecond discharge behavior at elevated density

Wolk, Benjamin M.; Ekoto, Isaac W.

High-voltage (20 kV peak), single-pulse, nanosecond, low-temperature plasma discharges were examined in nitrogen-diluted desiccated air (15.9% oxygen) with addition of 1%, 2%, and 3% carbon dioxide or water for a pin-to-pin electrode configuration in an optically accessible spark calorimeter at elevated density (2.9 kg/m3). Discharge behavior was characterized through pressure-rise calorimetry, direct imaging of excited-state atomic oxygen, and high-speed schlieren. Increasing carbon dioxide or water concentration led to an increased likelihood of surface discharges rather than the desired streamer discharge between the pin electrodes. For streamer discharges, carbon dioxide addition decreased the electrical-to-thermal conversion efficiency, while minimal impact was observed for water. Both carbon dioxide and water addition led to faster pressure rise rates. Carbon dioxide addition decreased excited state atomic oxygen signal, while water addition led to negligible changes. Finally, increased streamer branching was observed in the schlieren images when carbon dioxide or water was added to the gas mixture.