Non-uniform pulse discharge-induced radical production in distilled water

A spark discharge in water or in an aqueous solution can produce ultraviolet radiation and active species (radicals). In this paper, the characteristics of the spark discharge is investigated to identify the mechanism for the formation of radicals by the pulsed discharge. The spark discharge breakdown time and radical formation were studied using a needle-plate electrode system. The ultraviolet radiation and active species formation were studied for both the pulsed streamer corona discharge and the spark discharge. The distribution of OH radicals in space and time were investigated using emission spectroscopic analysis. The results showed that active species (. OH, . H, . O, H2O2) existed in the spark discharge, and that the hydroxyl radical (OH) was formed mainly within the discharge channel. In addition, the emission intensity of OH radical was higher in the case of the spark discharge than in the streamer corona discharge. (C) 1998 Elsevier Science B.V. All rights reserved.