Atmospheric pressure plasma acoustic moment analysis

Low-order moment around the mean (mean, standard deviation and skewness) analysis of the time evolving specific acoustic intensity of an air atmospheric pressure plasma jet is performed as a function of nozzle-to-surface gap (0.5 to 7 cm), drive frequency (19, 22, and 25 kHz) and air flow rate (35.7 to 76.6 l/m). The probability distribution of each time-series dataset exhibits deterministic correlations with contrasting entropy process regions afterglow (blown arc process (gap = 0.5 cm and 1740 ±100 K); and gap = 1 to 7 cm and 300 to 400 K)). The results indicate that the heated air is channeled along the surface and has a preferred backscatter an ular. In addition the blown arc process exhibits a skewness of +0.055 and the afterglow has skewness values from -0.05 to -0.4. These results illustrate how acoustic information can be used to differentiate plasma-surface entropy states.