Characterization of novel pin-hole based plasma source for generation of discharge in liquids supplied by DC non-pulsing voltage

Abstract

A recently presented novel plasma source generating discharge in liquids based on the pin-hole discharge configuration is characterized in detail. The system is supplied by DC non-pulsing high voltage of both polarities in NaCl water solutions at a conductivity range of 100-15 000 μS/cm. The discharge itself shows self-pulsing operation. The discharge ignition is observed in micro bubbles by transient discharge followed by a glow discharge in positive polarity at lower conductivities propagating inside the bubbles. At high conductivities, the glow regime is particularly replaced by a more energetic sequence of transient discharges followed by a shorter glow mode operation. The transient regime probability and its intensity are higher in the negative discharge polarity. The transient discharge produces acoustic waves and shock waves, which are observed at the moment of the bubble cavitation. The average gas temperature of 700-1500 K was calculated from the lowest OH (A-X) 0-0 band transitions. The average electron concentrations of 10 20 -10 23 m −3 were calculated from H α and H β line profiles. Finally, the production of a chemically active species is determined by hydrogen peroxide energy yields related to the energy consumption of the whole interelectrode system. All these quantities are dependent on the solution conductivity, the discharge polarity, and the applied power.

Influence of solution properties and gas addition on hydrogen peroxide production by a novel plasma source

“…As the previous results [20] indicated significantly higher production of hydrogen peroxide when positive polarity was applied on the main electrode, presented results are also focused on this configuration. An influence of pH and solution conductivity set by the chosen electrolyte is demonstrated in Figures 4 and 5 and obtained effective production rates of hydrogen vol.…”

“…The electrode system consisted of two electrodes [20]. The main jet electrode ( Figure 1) was constructed by a tungsten wire (diameter of 1.0 mm) which was inserted into a dielectric cylindrical rod made of Macor ceramics with outer diameter of 10 mm and with one conical end.…”

“…The system was supplied by DC non-pulsing high voltage up to 2 kV with the positive polarity on the main electrode. The discharge itself showed selfpulsing operation [20] giving the mean input power from the range of 50-150 W.…”

“…Production of chemical active species was represented by hydrogen peroxide formation. Concentration of hydrogen peroxide was determined by a standard colorimetric method using a specific titanium reagent [20,22]. Uncertainty of hydrogen peroxide estimation varied from 5 to 10 %.…”

“…In both electrode modifications (without and with the gas addition), the discharge is generated by DC non-pulsing voltage in various electrolyte solutions giving different pH values. Thus the previously published detailed characteristics of this plasma source [20] are extended by chemical experiments focused on hydrogen peroxide determination in the dependence on solution properties and gas addition.…”