Knowledge of species concentrations in environments such as plasmas and combustion is important for developing and refining a predictive understanding of chemical transformations under extreme conditions. However, quantifying such measurements for reactive species is highly challenging. CRF researchers Jonathan Frank, Erxiong Huang and Sebastian Pfaff with colleagues from MIT, demonstrated quantitative time- and spatially-resolved measurements of oxygen atoms in a discharge, published in a paper entitled “O-atom TALIF measurements in a nanosecond pulsed microdischarge upstream and downstream of an oxygen-enriched methane air flame” in Plasma Sources Science and Technology. In this paper, the authors present time-resolved, 2D absolute measurements of atomic oxygen (O-atom) mole fractions from a spatially stabilized nanosecond repetitively pulsed microdischarge in an oxygen-rich, fuel-lean, premixed methane-air flame environment using two-photon absorption laser-induced fluorescence (TALIF). The authors achieved absolute calibration by photodissociating a known amount of NO2 in the environment of interest. By spatially pinning the discharge and propagating the flame across it, quantitative measurements were obtained in both the reactant and product streams during intrapulse and interpulse periods. Results show that both the incident voltage pulse and subsequent reflections drive O-atom production. They also reveal differences in the magnitude and spatial distribution of plasma-generated O-atoms in the reactant and product streams. These quantitative measurements show discrepancies with predictions, which will enable improvement of plasma chemical kinetics models and refinement of models to account for neglected fluid effects.
For more details: https://iopscience.iop.org/article/10.1088/1361-6595/ae9be7