Plasma Actuator Efficiency Loss due to Heat

This study presents advances in understanding the complex operation of surface dielectric barrier discharge (SDBD) plasma actuators. Actuator performance at higher frequencies was analyzed using a 20 kHz high-voltage power supply. Operation at high power revealed a decrease in generated force over time, primarily attributed to intense heating of the gas and dielectric. IR camera measurements showed dielectric temperatures exceeding 100°C after one minute of operation, and rotational temperatures of N₂, calculated from optical emission spectra, were above 700K. These high temperatures suppress the production of negative oxygen ions, which are key contributors to the electrohydrodynamic (EHD) force. Concentration of O₃ and other species above the plasma were monitored using UV-Vis absorption spectroscopy and FTIR gas cell absorption, with ozone selected for its easy detection and known thermal degradation properties. Both methods demonstrated a decrease in O₃ concentration with increasing temperature. Stable force and ozone concentrations were observed at lower plasma power, where dielectric temperature remained below 50°C. However, increasing power and temperature caused an immediate drop in both force and ozone concentration. Ion concentrations at different temperatures were also simulated using COMSOL, confirming the experimental results. These results enhance our understanding of SDBD plasma actuators and further confirm the critical role of oxygen ions in EHD force production.