Abstract: The combustion process of hydrocarbon fuel will produce a lot of carbon smoke. C2H2, as an important precursor of carbon smoke products, has an important effect on carbon smoke generation, so it is of great significance to achieve direct detection of C2H2 in combustion environment. In this work, a tunable diode laser absorption spectroscopy system was established to detect C2H2 gas absorption spectra at different temperatures and pressures by simulating combustion environment in a high temperature and high pressure gas pool. Specifically, taking a tunable semiconductor laser with a central wavelength of 1542 nm as the light source, the absorption line extinction signals of acetylene at 6489.074 cm−1 and 6490.020 cm−1 were obtained using the scanning wavelength direct absorption method, thereby achieving simultaneous measurement of C2H2 concentration and temperature. The experimental results show that, in the pressure range of 1.01 × 105 –5.05 × 105 Pa and temperature range of 500–1100 K, the relative average standard deviations of gas volume concentration and gas temperature measurement are 4.59% and 2.47% respectively, which are in high agreement with the reference values. It proves that the developed system in this work can provide assistance for simultaneous measurement of gas concentration and temperature under high temperature and high pressures.

Key words: spectroscopy, tunable diode laser absorption spectroscopy, high temperature and pressure, flow diagnose