Preliminary Investigation of Prebreakdown Phenomena and Chemical Reactions Using a Pulsed High-Voltage Discharge in Water

Prebreakdown phenomena in water were investigated for point-plane geometries using high-voltage pulses. Spot discharges, filamentary magenta streamers, isolated microdischarges, and microbubbles were observed and photographed. Emission spectra were obtained using a prism spectrograph. Maximum streamer lengths were determined as a function of applied voltage, pulsewidth (decay constant), and water conductivity. The bubbling of gas through the underwater discharge resulted in the disintegration of the gas bubbles, and also caused gas-phase discharges to occur near the nozzle electrode. The production of 0
3
, accomplished by bubbling O
2
gas through a discharge in deionized water, was investigated using a colorimetric indigo dye test that measured the concentration of 0
3
in the water. Chemical reactions occurring when 0
2
or N
2
gas was bubbled through a discharge in an anthraquinone dye solution were studied by photometrically measuring the decolorization of the dye.