Propagation of positive streamers on the surface of shallow as well as deep tap water in wide and narrow dielectric channels

Abstract

The results of experiments studying long-living positive streamers propagating on the surface of tap water are presented; the plasma-forming gas is air at atmospheric pressure. Measurement data for the strength of the longitudinal electric field in the surface streamer, the streamer velocity versus time until it stops, and the length of the streamer versus the applied voltage are presented. It is revealed that the depth of the water in a basin influences the streamer length: the deeper the water, the longer the streamer. Besides this, restricting the transverse direction of the area in the water accessible for streamer extension suppresses streamer branching until it fully disappears. It is shown that non-branching streamers propagating in narrow water channels increase their length considerably. Placing a dielectric plate with long, narrow slits of the required configuration on the water enables one to control the trajectory of streamer propagation. Three-dimensional numerical calculations of the spatial structure of the electric field and the current inside and outside the streamer in the water basin with different depths and widths were made. It is shown numerically that the streamer length and its diameter strongly influence both the strength and spatial structure of the electric field in the air around the streamer.

Nanosecond pulsed plasma discharge over a flowing water film: Characterization of hydrodynamics, electrical, and plasma properties and their effect on hydrogen peroxide generation

“…For pulsed discharges that form filamentary plasma channels which propagate along the surface of a gas/liquid interface, it is of interest to conduct studies such that the flow of gas and liquid and resulting contact with the plasma channels can be controlled. In our previous work we have constructed a small gas/liquid tubular reactor that allows for characterization of plasma channels propagating along a flowing gas/liquid interface . The small tubular reactor allows for continuous flow of both the gas and liquid phases and can be adapted for chemical degradation and synthesis .…”

Water activated by the atmospheric air streamer‐to‐spark transition discharge over its surface

“…The applied voltage of the HV pin electrode ($$U(t)$$) decreases when the electric current ($$I(t)$$) flows through the water layer, resulting in the joule heating of the water. [ 24 ] Our measurements indicate that the joule heating does not increase the biological reactivity of water. An increase in the biological reactivity of water is primarily due to the deposition of electric energy into the surface streamer.…”

“…The nonbranching and snake‐shaped air streamer has been reported previously, which propagates in narrow water channels. [ 24 ] Our design can be very helpful for increasing the horizontal electric field over the surface of water, which contributes to the propagation of air streamers. However, the positive air discharge gets much weak at d = 140 mm, and it is generated in the vicinity of the HV electrode.…”

“…The air streamer over the surface of water is up to 115 mm in length, and the electrical breakdown eventually leads to the formation of a spark discharge. [ 24 ] The air discharge over the surface of water can significantly contribute to the diffusion and dissolution of reactive species including short‐lived molecules, radicals, and ions into water. The primary generation process of OH radicals is closely related to the air discharge over the surface of water, thus the subsequent processes of diffusion and dissolution have an influence on the chemical reactions.…”

“…[ 25 ] A long‐grounded electrode with a width of 50 mm placed on the bottom of a dielectric cell can be used to confine the streamers and increase the length of air streamers on the surface of water. [ 24 ] The air discharge on the surface of water can be ignited by a lower voltage, and they can propagate over a longer distance in comparison with those of conductive tap water. However, the effect of water conductivity on the propagation of air discharge over the surface of water should be further studied to efficiently control the air discharge and increase their energy efficiency.…”