Spatiotemporal behaviors of absolute density of atomic oxygen in a planar type of Ar/O₂ non-equilibrium atmospheric-pressure plasma jet

A method combining of two-photon absorption laser-induced fluorescence and vacuum ultra-violet absorption spectroscopy is constructed and used to get the fine spatial distribution of O generated by a planar type of Ar/O₂ non-equilibrium atmospheric-pressure plasma jet. The O density in the quasi-uniform region, which occupies about 80% of the total plasma width, is as high as 10¹⁵ cm⁻³. The lifetime of O is estimated to be about 360 ± 60 µs. The loss of O atoms is due to the three-body reaction of O + O₂ + Ar → O₃ + Ar confirmed by a simple calculation with a few rate equations. The results are very useful for the simulation of Ar/O₂ plasmas, the design of large-scale planar plasma jets and the development of their potential applications. (paper)