Acoustic-based laser induced breakdown thermometry

Obtaining accurate temperature measurements is an essential task in flame studies and, since the sound pressure generated during laser-induced breakdown is strongly dependent on the local gas density, it is possible to utilize this information to infer temperature. In this study, we introduced the concept of acoustic-based laser induced breakdown thermometry. This technique was first demonstrated using a McKenna burner, where a strong correlation between the thermocouple-measured temperature and the measured acoustic signal was established. Utilizing the obtained calibration profile, the temperature distribution in a counter-flow diffusion flame was further measured and the results compared favorably with numerical results. The accuracy of LIBT technique was analyzed as a function of sample number to shed light on future applications where higher temporal resolution is preferred. This work suggests that acoustic-based laser induced breakdown spectroscopy holds promise as a simple alternative for simultaneous measurement of temperature and elemental composition in flame environments.