Plasma-Assisted Combustion

Plasma-assisted combustion (PAC) can extend flammability and lean blow-off limits to enable low-NOx combustors, lower ignition thresholds, and mitigate combustion dynamics. When using Nanosecond Pulsed Discharges (NPD), one of the main pathways of combustion enhancement is through O-atom production by direct electron impact dissociation and dissociative quenching reactions of electronically excited molecular nitrogen. These O-atoms can also participate in NOx formation routes. In this work, we use two-photon-absorption laser-induced fluorescence (TALIF) to quantify O atom densities produced by a single microdischarge in isolated reactant and product regions of an oxygen-enriched laminar premixed methane/air flame. The single microdischarge is generated by nanosecond repetitively pulsed discharges operated in a dielectric barrier discharge configuration. The setup allows to image the discharge along the main axis of the microdischarge by utilizing indium tin oxide (ITO) transparent electrodes. Alternative approaches for calibrating O-atom TALIF signals were investigated, for comparison with the standard Xe TALIF method.

Funding acknowledgement

This work was conducted at the Low Temperature Plasma Research Facility at Sandia National Laboratories and was supported by the U.S.Department of Energy, Office of Science, Office of Fusion Energy Sciences.