D) in an atmospheric pressure argon plasma jet

An extensive study on green emission characterization is presented using a single dielectric barrier discharge (DBD) geometry argon plasma jet, driven by a kHz sine voltage. The plasma was generated with 99.999% pure argon, and the observed 557.7 nm green line resulted from the excited O(¹S) state. Optical emission spectroscopy (OES), utilizing argon line ratios, was employed to determine the electron density and electron temperature under varying conditions in the downstream region. The study discusses how discharge characteristics and green emissions vary with changes in interelectrode distance, applied voltage (power) and flow rate. Two discharge regimes are identified, each associated with distinct branches of green emission intensity, concluding that the 557.7 nm emission is favoured in a low electron temperature environment. By charging the two electrodes in two opposite ways, it is shown that the green emission from oxygen is favoured in the case where the electric field and the electron drift are not continuous.