Production rates of hydrogen and oxygen on surface of water jet injected into low-pressure hydrogen and oxygen plasmas

In a previous work (T. Ito, T. Sakka, and K. Sasaki, PSST \textbf{31}, 06LT02 (2022)), we observed the productions of molecular hydrogen and oxygen via currentless redox reactions on the surface of water jet injected into a low-pressure inductively coupled helium plasma. In the present work, we compared the production rates with those in hydrogen and oxygen plasmas. We observed that the production rates were proportional to the electron density. This is the same result as that observed in the helium plasma, and it supports the productions of hydrogen and oxygen by redox reactions (reactions induced by the transport of a pair of electron and positive ion). However, the production rates were dependent on the working gas. For example, at the same electron density, the maximum production rate of molecular hydrogen was observed in the hydrogen plasma, intermediate in the helium plasma, and minimum in the oxygen plasma. This experimental result suggests that the reactions are not simple redox reactions. Possibilities are the involvement of ionic species and neutral radicals to reaction processes.