Experimental studies of the absorption and emissions from laser-induced spark in combustible gases

This paper reports preliminary results of experimental measurements of the emission and absorption of laser-induced spark in air, O 2, N 2, H 2, and CH 4 using a Q-switched Nd-Yag laser operating at 532 nm and 1064 nm, with a pulse duration of 5.5 ns. Line radiation spectra observed for spark in air consist of N and O lines that are distinctly observed in the region from 399.49 to 870.2 nm. The spectra of spark created in CH 4 show strong H lines centered at 656.46 nm. Some rather weak emission lines are also observed at 460.4, 497.0, 497.3, and 503.7 nm. Laser wavelength has a strong effect on the absorption data obtained as a function of total laser energy E o. However, in case of variable pressure, its effect is considered to be within experimental fluctuations.