Optical diagnosis of an argon/oxygen needle plasma generated at atmospheric pressure

An atmospheric-pressure argon/oxygen needle plasma discharge is generated in a long dielectric tube and investigated with respect to its electrical characteristics and the production of oxygen atom by means of optical actinometry. The length of discharge column depends on the operating frequency and applied voltage of power supply, which is interpreted qualitatively with an equivalent circuit model. Moreover it is found that there exists an optimal value of oxygen concentration in the production of oxygen radicals. At last, the oxygen/argon plasma is employed to modify the interior surface of a fine quartz tube to demonstrate its potential applications.