Laser-Induced Breakdown Spectroscopy (LIBS) For The Characterization Of Methane-Air Laminar Diffusion Flame

Abstract

Laser-induced breakdown spectroscopy (LIBS) was applied for the characterization of the methane-air laminar diffusion flame, revealing the spatial distribution of its composition. From the measurement, it was found that distribution of the atomic and ionic N emissions produced by the flame had obvious differences, which were mainly distributed in the air area and flame area, respectively. A comparison of the LIBS spectra of air, methane gas, and methane-air laminar diffusion flame showed that the atomic N emissions were mainly produced by the excitation of N2, and the ionic N emissions were more related to the N-containing combustion products. In addition, the correlation between typical emissions and the flame temperature measured by thermocouple was estimated to show that the tendency of the changes in temperature can be characterized by C2 emission intensities. This work provides a new method for real-time online flame temperature measurement, and also provides a reference for revealing the formation process and conversion pathway of each component in the flame.