Characterization of an atmospheric pressure plasma jet producing the auroral transition O(1S) to O(1D)

Abstract We present a detailed characterization of an atmospheric pressure plasma jet that produces the metastable oxygen states O( 1 S) and O ( 1 D) with emission of the ‘auroral’ green line. The device used 99.999 % pure argon as a working gas for the plasma generation. Optical emission spectroscopy was used to understand the active species present in the plasma jet and to infer the mechanism of O( 1 S) creation and destruction. The continuum spectrum was used in conjunction with a method based on machine learning for determining the arbitrary electron probability distribution function. Discharge and plasma properties were estimated from Lissajous plots and using calculations with the BOLSIG+ software. The metastable oxygen forms for all operating parameters of the plasma jet system in a linear electrode configuration. The camera images provided information of the overall plasma jet behavior as parameters were altered. While the metastable oxygen was produced for every iteration, the plasma jet behavior changed considerably when the powered and grounded electrodes are switched. Small admixtures of oxygen and nitrogen were introduced in the plasma jet to understand the kinetic processes of metastable oxygen destruction and the 557.7 nm auroral line. This behavior has implications for plasma reactive chemistry in fundamental areas such as auroral physics as well as technological applications of plasmas.