Characteristics of plasma in culture medium generated by positive pulse voltage and effects of organic compounds on its characteristics

We describe a positive pulse voltage method for generating plasma in culture medium with a composition similar to biological fluids. We also describe the plasma's characteristics, liquid quality, and the effect of organic compounds in the culture medium on the plasma characteristics through comparisons to a solution containing inorganic salts at the same concentrations as in the culture medium. Light emission with Na and OH spectra was observed within a vapor bubble produced by Joule heating at the tip of the electrode. A downward thermal flow and shock wave were caused by the behavior of the vapor bubble. The culture medium pH gradually increased from 7.9 to 8.3 over the discharge time of 300 s. H₂O₂ was generated 1.1 mg l⁻¹ in the culture medium after discharge for 300 s, and this value was 0.5 mg l⁻¹ lower than the inorganic salts solution which does not contain organic compounds. This study provides important data that will help facilitate more widespread application of plasma medicine. (paper)