Driving frequency dependency of gas species in the bubble formation for aqua-plasma generation

Effects of voltage driving frequency on the gas composition, electrical and optical emission properties of aqua-plasmas generated in electrolyte solution, are investigated and the experiment was carried out in the range of 10 Hz–50 kHz. In the range of 10–300 Hz, H2 dominated bubbles are generated and it is attributed to electrolysis. With increasing frequency, the gas composition inside the bubble changes to the H2O which can be determined from the observation of atomic H to OH(A-X) transition from the optical measurements of aqua-plasma. In higher frequency than 2 kHz, the boiling on the electrode dominates to the formation of the bubble. Consequently, the radicals and plasma properties are varied with the driving frequency.