Visualization of the Two-dimensional Distribution of ROS Supplied to a Water-containing Target by a Non-thermal Plasma Jet
T. Kawasaki1, K. Kawano1, H. Mizoguchi1, Y. Yano1, K. Yamashita1, and M. Sakai2
1Department of Mechanical and Electrical Engineering, Nippon Bunri University, Japan
2Department of Media Technologies, Nippon Bunri University, Japan
Abstract- The supply mechanisms of reactive oxygen species (ROS) to a water-containing target by a plasma jet should be clarified. In this study, we investigated the two-dimensional distribution of ROS supplied to the target by a plasma jet using a gel reagent with iodine-starch reactions in atmospheric air and determined the effects of the irradiation distance and the addition of O2 to He on the ROS distribution. Relative ROS concentration distributions were also obtained from visualized distributions by measuring the absorbance. In the He plasma jet, we clearly observed a doughnut-shaped ROS distribution on the target under certain conditions. The efficiency or local ROS supply to the target could be controlled by adjusting the irradiation distance. The results also indicated that short-lived species generated at the contact point between the He plasma jet and the target primarily supplied the ROS to the target. In contrast, in the O2/He plasma jet, results indicated that the ROS distribution was influenced by the synergistic effect of long-lived species, for example O3 generated in the gas phase over the target, along with the short-lived species.
Keywords-Atmospheric pressure non-thermal plasma jet, ROS distribution, gel reagent, plasma medicine