Spatio-temporal behaviors of atmospheric-pressure plasma jets for investigation of reactive-species production in liquid

Medical treatments with non-equilibrium atmospheric-pressure plasma jets have attracted great interests due to significant medical effects including cancer therapy. For biomedical applications of the plasma jets, it is of great significance to understand interactions of the plasma jet with liquid because the cellular tissue is covered with aqueous solutions, and biological behaviors are induced by reactive oxygen and nitrogen species (RONS) in the aqueous solutions through interaction with plasma-jet systems [1]. In this study, effects of the plasma contacting conditions with liquid surface (direct contact and non-contact to the liquid surface) on RONS production in aqueous solutions have been investigated through characterization of spatio-temporal behaviors of the plasma jets; high-speed image observations with intensified CCD (ICCD) camera, fluid dynamic characterization of gas flows with Schlieren method, and electrical characterization of the plasma-bullet propagation onto substances for explicit evaluation of the plasma-jet contacting states [2]. Concentrations of H2O2 and NO2− in the aqueous solutions have been measured for comparison of the plasma contacting conditions with liquid surface (direct contact and non-contact to the liquid surface) and for evaluations of the biological effects. Additionally, experimental factors for controlling concentration ratio of H2O2 and NO2− in water will be presented.