Characterization of Ozone Density and Reactive Species Production within Liquid Solutions for a Microsecond-Pulsed Power Supply

Within recent modeling and experimental studies, atmospheric pressure plasmas have shown great promise for the treatment of wounds and cancerous tumors. In these applications, samples are usually covered by a thin layer of a biological liquid [1]. Therefore, a self-built, microsecond pulsed power supply was developed based on previous work from Kogelheide et al. [2], to experimentally test the use of a dielectric barrier discharge (DBD) on ozone and reactive species production within liquid solutions. A cylindrical copper electrode covered by aluminum oxide (Al₂O₃) was utilized to treat various media. In this study, ozone density and reactive species production were measured utilizing Optical Absorption Spectroscopy (OAS), and colorimetric assays. OAS was used to determine the absolute density of ozone produced within the plasma volume of the DBD. Voltage, current, and charge measurements were also performed to characterize the pulsed power supply in order to determine plasma parameters such as displacement current, plasma voltage, and dissipated power. Treatments took place within liquid solutions such as distilled water, cell media, and a cysteine solution to determine the variations in ozone production based on the media treated and the species produced through variations in repetition frequency. Frequency sweeps found that ozone density increased with an increase in repetition frequency with respect to plasma discharges of the liquid solutions. Ozone production was determined to have the highest production at a repetition frequency of 300 Hz for each test case.