The transient processes associated with the interaction of a Bunsen flame and nanosecond pulsed discharges (NPD) are explored experimentally with two optical methods. A nanosecond-gated schlieren system is employed to image the shockwave propagation and the hydrodynamic response of the flame to NPD while the time-resolved optical emission spectroscopy measurements are carried out to determine active species and temperature in the plasma region created by the discharges. Therefore, the unsteady process of the interaction of the flame with the discharges is recorded in real-time by the combined measurements. Numbers of experimental evidences for understanding the dynamics of non-equilibrium plasma produced by NPD and performing further numerical simulation are offered.

Abstract. Nanosecond pulsed discharges were applied to an experimental study for exploring the temporal response of a premixed methane/air Bunsen flame with two optical diagnostic methods. The microstructure and dynamic response of flame to the discharges was observed by a schlieren system, and the radial velocity of the shock wave was also measured. Time-resolved optical emission spectroscopy offered intermediate species, their evolutionary timescales and temperature in the plasma region. While the ultrafast heating mechanism of NPD was confirmed, the experimental results also provided lots of critical data for understanding the dynamics of non-equilibrium plasma produced by NPD and performing further numerical simulation. In addition, it also indicates that NPD can stir reactant gases and interact with flame by the generated shock wave and vortices while it produces more reactive plasma than LIBS. It makes the technique may be more suited for applications in combustion enhancement and instability control.