Diagnostic of hydroxyl radical concentration in high pulse voltage triggered dielectric barrier discharges

Summary form only given. We have developed a diagnostic of absolute concentration measurement based on a time resolved resonant absorption spectroscopy. The probe signal *OH(A/sup 2//spl Sigma//sup +/-X/sup 2//spl Pi/, /spl lambda//spl ap/308 nm) is generated in a high pulse voltage triggered DBD probe. The gas mixture (1 atm argon+200 ppm water vapor) was optimized to adjust lifetime and intensity of the *OH(A-X) UV fluorescence. This signal is sent through the main DBD plasma, After absorption, the output signal is used to calculate the *OH(X) concentration in the main discharge. The delay between the onset of the main discharge and the probe pulse can be adjusted in order to probe the fundamental level *OH(X) during the whole post-discharge. This diagnostic has been tested first in argon+water vapor mixtures. Various effects of discharge parameters like input energy or water vapor concentration on the *OH(X) density have been clarified. Next more practical gas mixtures like air+water vapor+pollutant (TCE) mixtures have been investigated. The temporal decay of *OH(X) radical concentration with and without TCE has been studied. The decay frequency of *OH(X)is in good agreement with the literature data and allows to valid this diagnostic.