The Effect of Driven Power Source on the Discharge Characteristics of APPJ

Atmospheric pressure plasma jets (APPJs) can be driven by positive pulses, negative pulses, and sinusoidal ac excitations. The plasma jets under different excitations have different characteristics. In this article, a plasma jet system driven by three different power sources is established. The electrical and spectral characteristics of the jet as well as the vibration and rotation temperature of the plasma are studied. The results show that the peak discharge current of the pulsed plasma jet occurs along the rising and falling edges of the pulse voltage. The ac plasma jet will randomly appear with multiple discharge current pulses, but the peak current is much smaller than that of the pulse discharge current, and the input power of the sinusoidal ac plasma jet is significantly higher than that of the pulsed plasma jet. With the increase of discharge voltage, the length of the three plasma jets increases gradually, and the positive pulse plasma jets are the longest at each voltage. The luminescence intensity of three excitation particles (OH at 309.0 nm, N2 at 337.1 nm, and N2 at 357.6 nm) under three power sources was analyzed. The intensity of active particles in ac plasma jet is higher near the nozzle. With the increase of axial distance, the intensity of excited active particles in the positive-pulsed plasma jet increases. The rotating temperature of ac jet is 20-30k higher than that of pulse jet. The vibration temperature of pulsed plasma is higher than that of ac plasma jet. With the increase of jet axial distance, vibration temperature and rotation temperature change little.