Ozone Concentration Measurement of an Atmospheric Pressure Air Plasma Jet by Ultraviolet Absorption Spectroscopy

Atmospheric pressure plasma jets have great potentials for various biomedical applications due to abundance with active oxygen species. In this article, an air plasma jet with a geometry of microhollow cathode discharge has been developed, which operates in a pulsed mode or a continuous mode depending on the dissipated power of the plasma jet. There are some continuous spectra emitted from the plasma jet, whose integrated intensity indicates that electron density increases with the increase of dissipated power, while decreases with increasing air flow rate for both of the two modes. Moreover, the electron density in the continuous mode is higher than that in the pulsed mode. Gas temperature of the plasma jet is obtained by the best fitting of the simulated and the experimental optical emission spectrum of OH (A-X), and ozone concentration produced by the plasma jet is measured by means of ultraviolet absorption spectroscopy. Results indicate that both ozone concentration and gas temperature decrease with increasing distance from the jet nozzle. At the jet nozzle, both of them increase with increasing dissipated power. However, ozone concentration decreases, while gas temperature increases with increasing air flow rate. The results are very important for the biomedical application of plasma jet.