Gas-liquid Interfacial Plasma Using High-speed Liquid Flow for Analyzing Short-lived Reactive Species Transport*

Atmospheric-pressure plasmas (APPs) have recently emerged as a novel technology for life science (medical and agricultural) applications. Although APP-produced short-lived reactive species in the liquid phase could be key factors in their applications, the analysis of the short-lived reactive species transport is still challenging due to their high reactivity and coexisting various species. In order to analyze decay of OH radical (one of important short-lived reactive species) in APP-exposed water, we developed a He-APP device with high-speed (\textasciitilde 10 m/s) liquid flow. This system gives a high temporal resolution measurement of OH radical in the liquid phase. We have experimentally measured APP-produced OH radical decay and showed a space-time distribution of OH radical based on a reaction-diffusion model which is consistent with the experimentally obtained OH radical decay.