Alternating current-driven non-thermal arc plasma torch working with air medium at atmospheric pressure

This work is devoted to the investigation of the discharge characteristics of high-frequency alternating current (ac) plasma torch working with air medium using electrical and spectroscopic techniques. A simple structure and compact ac plasma torch associated with a resonance power supply allows the generation of low power discharges (lower than 1 kW) with high voltage and low current. The discharge shows a negative resistance characteristic, and its curve shifts up with gas flow increased. The effects of power on the emission intensity of NO ( A 2 Σ + → X 2 Π), OH ( A 2 Σ → X 2 Π, 0–0), N 2 ( C 3 Π u → B 3 Π g ), H α and O and their spatial distributions in plasma jet axial direction were investigated. It has been found that the emission intensities of NO, OH, N 2 , H α and O rise with an increase in power dissipation. With increasing axial distances of plasma jet from nozzle exit, the emission intensity of OH increases and then decreases, while the emission intensities of other species decrease sharply. The vibrational temperature is much higher than the gas temperature, which demonstrates the ac-driven arc discharge deviation from thermal equilibrium plasma.