On different modes of a filamentary atmospheric pressure plasma jet: modeling, laser schlieren deflectometric and high-speed camera investigations

Abstract We investigated a filamentary non-thermal atmospheric pressure plasma jet used for coating applications. The plasma jet exhibits two different modes, the stationary mode and the locked mode, in which the filaments rotate around the plasma jet axis. We present a model for the modes and verify it by measurements with high-speed camera and laser schlieren deflectometry. Laser schlieren deflectometry investigations reveal a drift of the rotation frequency over time towards lower values. Additionally, relations between the filament rotation frequency and gas flow as well as input power, respectively, are investigated by the laser schlieren deflectometry. Correlation between rotation frequency and gas flow show a linear dependence and with increasing power the rotation frequency increases as well. All the results are in agreement with the proposed model. Graphical abstract