Regime transitions of a pulsed nanosecond discharge during passage of a transient flame*

Repetitively pulsed nanosecond discharges are a promising way of controlling combustion processes. Whereas most works have centered on the impact of the plasma on different combustion phenomena (extension of lean blowout limits, ignition delay time reduction, static and dynamic flame stabilization, etc.), fewer studies have been devoted to the implications of having a strongly inhomogeneous environment, often unsteady in time, on the discharge characteristics. This two-way coupling is relevant since it will affect the plasma regime observed, the spatial structure of the plasma-activated zone, the total energy deposition, and the energy pathways and chemical kinetics activated by the plasma; which can be evolving at the flame dynamics timescale. In this contribution we present a relatively simple burner configuration, a rectangular cross-section quartz tapered channel, supporting a propagating laminar premixed flame. A repetitively pulsed nanosecond discharge in a dielectric barrier discharge configuration is generated at a fixed location within the burner and the temporal evolution of individual pulses is studied during the flame passage. High speed imaging, energy measurements and translational and vibrational temperature measurements are presented and discussed.