Electric Field Measurements in a Plasma Assisted Burner

This study reports measurements of electric field in atmospheric-pressure nanosecond repetitively pulsed (NRP) discharges generated in a plasma-assisted combustion (PAC) burner. The electric field has a prominent role in determining the plasma chemistry, and hence its quantification and characterization is required for understanding the coupling between plasma discharges and flames. Measurements are conducted using the electric field induced second-harmonic generation (EFISH) laser diagnostic technique¹. With this non-intrusive technique, high temporal (sub-ns) and spatial resolution results can be obtained. In this experiment, a picosecond Nd:YAG laser is employed and the EFISH signal is collected with a photomultiplier. The burner features a pin-to-pin electrode configuration. A methane-air flame is established in the 10-mm electrode gap and NRP discharges in the glow regime² can develop across the gap. The experimental configuration and the post-processing have been carefully selected to better resolve the steep gradients formed in this non-homogeneous field. Calibrations against Laplacian fields allow the quantification of the electric field in the fresh gases before the flame front. Results are given in terms of temporally and spatially resolved EFISH signal and electric field estimations. In the discharge formation, an ionization wave is observed and its dynamic is analyzed. The provided data are useful for future modeling of the NRP discharges in combustion environments and complex media.