Diagnostics of Dielectric Barrier Discharge at Atmospheric Pressure by Laser Spectroscopic Measurements

Spatial distribution of electron density inside parallel plate dielectric barrier discharge (DBD) is discussed in this presentation by using CO2-laser heterodyne interferometry measurement. This interferometry measurement has been used for low pressure plasmas and applied to DC microplasmas at atmospheric pressure recently. To derive the electron density inside pulsed plasmas like DBD, we used 125 Hz pulsed modulation of the applied voltage at 30 kHz and measured a duty ratio of the plasma by the discharge current and time-resolved optical emission spectroscopy measurement. From the experimental results, we derived the spatial distributions of the peak absolute density of electron between two electrodes, and high density regions were observed near the electrodes.