Controlling the nitric and nitrous oxide production of an atmospheric pressure plasma jet

Atmospheric pressure plasma jets are non-thermal plasmas and have the ability to create reactive species. These features make it a very attractive tool for biomedical applications. In this work, we studied NO and N$_{\mathrm{2}}$O production, which are two species having biomedical properties. NO plays a role in the vascularization and in ulcer treatment, while N$_{\mathrm{2}}$O is used as anesthetic and analgesic gas. In this study, the plasma source is similar to the COST Reference Microplasma Jet (\textmu --APPJ). Helium is used as feed gas with small admixtures of molecular nitrogen and oxygen of below 1{\%}. The absolute densities of NO and N$_{\mathrm{2}}$O were measured in the effluent of an atmospheric pressure RF plasma jet by means of ex-situ quantum-cascade laser absorption spectroscopy via a multi-pass cell in Herriot configuration. We will show that the species' production is dependent on several parameters such as power, flow and oxygen and nitrogen admixture. The NO and N$_{\mathrm{2}}$O densities are strongly dependent on the N$_{\mathrm{2}}$-O$_{\mathrm{2}}$ ratio. Changing this ratio allows for choosing between a NO-rich or a N$_{\mathrm{2}}$O-rich regime [1]. [1] Douat \textit{et al}, \textit{PSST}, \textbf{25} (2016) 025027