One-dimensional temperature measurement of gases based on femtosecond laser-extended electrode discharge spectroscopy (FEEDS)

Abstract

Temperature, and hence thermometry techniques, are critical for characterizing gaseous flows and flames. Therefore, it is always attractive to develop new thermometry techniques to satisfy different demands. Here, we propose a thermometry technique for one-dimensional gas temperature measurements based on femtosecond laser-extended electrode discharge spectroscopy (FEEDS). By FEEDS measurements in gas flows containing hydrogen, we found that the temperature of the gas flow has a strong correlation with the full width at half maximum (FWHM) of the atomic hydrogen line at 656 nm, and this correlation is monotonic in the temperature range we measured, i.e., the temperature of gas flows can be extracted by measuring this FWHM. We applied this technique to methane/air gas mixtures and realized temperature measurements in the range of 300–1806 K with an error of ∼50 K. Also, we found that the technique has the capability to achieve one-dimensional measurements; more importantly, we found that changes in the stoichiometric ratio of the gas mixture do not affect the temperature measurements. Finally, we applied this technique to a premixed methane/air jet flame.