Discharge Dynamics and Modes of an Atmospheric Pressure Non-Equilibrium Air Plasma Jet

A plasma jet operated with atmospheric pressure air is presented. Unlike the dynamics of plasma jets working with noble gases, the propagation of the jet that is operated with air is primarily determined by the gas flow. This jet can be generated by applying a continuous, i.e., DC high voltage. However, depending on the applied voltage and gas flow rate a true DC operation can be distinguished from a self‐pulsing mode. The gas temperature of the plasma plume when operated in the pulsed mode is lower than for the DC mode. Conversely, emission intensities of atomic oxygen, O, and nitrogen species, N2 and ${\rm N}_{2}^{ + } $, are much higher for the pulsed mode than observed for DC operation. The propagation velocity of a plasma jet that is generated from air is determined by the gas flow. Depending on the applied voltage and flow rate a DC mode can be distinguished from a self‐pulsing mode. In the latter case plasma bullets are expelled that propagate at much lower velocities than previously reported for plasma jets with noble gases. In the self‐pulsing mode emission intensities of reactive species are higher providing a potentially higher efficacy for medical applications.