Effect of high-speed repetition of traveling wave voltage pulse on streamer initiation in water

Time lag distributions for the streamer initiation in water subjected to a reciprocal traveling wave voltage pulse were measured as a fundamental study of water treatment for pollution control. A point-plane electrode gap in de-ionized water was connected with a capacitor which was charged and then grounded through a pulse-forming coaxial cable. Since the cable was directly grounded without any resistance, the reciprocal traveling wave propagated along the cable with a change in its polarity. Laue plot of the streamer initiation time lags showed that the initiation probability during the second pulse application became much higher than that during the first pulse application. This fact implied that some physical processes during the rest-time just after the first pulse enhanced the streamer propagation probability at the second pulse application. Spectroscopic measurement of the repetitive discharges was also carried out using a monochromator and a photomultiplier. A discharge light signal having a spectrum which corresponded to excited OH radical emission was repeatedly detected for a long period.