Radical Production in a Short-Pulse Excited, Flowing Gas Atmospheric Pressure Dielectric Barrier Discharge

The production of plasma-chemical radicals in a short-pulse excited atmospheric pressure Ar / H$_{2}$O or He / H$_{2}$O dielectric barrier discharge as a function of gas flow rate and H$_{2}$O concentration was investigated. The plasma emission of excited Ar, He, OH, and N$_{2}^{+}$at 750, 706, 308,and 391 nm, respectively, were recorded for various flow conditions and H$_{2}$O concentrations as well as applied voltage. The change in plasma emission with different conditions was measured either by temporally integrated dispersed emission with a spectrometer/CCD or temporally resolved, wavelength selected emission with a spectrometer/gated PMT. The OH radical production increased with applied voltage and also with small additions of water but the emission was greatly reduced with higher water concentrations. The temporally-resolved OH and N$_{2}^{+}$ emission was delayed with respect to the excited Ar and He emission due to the heavy particle production of OH and N$_{2}^{+}$. The radical production as function of applied voltage, gas flow rate, and gas mixture will be presented.