Spectral characterization of laser-induced air plasma by pulsed CO2 laser

The spectral characterization of laser-induced air plasma by a pulsed TEA CO2 laser with a GaAs lens is reported. The data were collected using an ICCD spectrograph. The spectra of laser-induced plasma in the range of 300-900 nm and their spatial and temporal behaviors were investigated. Emission spectra of the N II lines occurring between 490 and 520nm were analyzed in detail. The intensity peaks during the laser pulse approximately 0.7 μs and the peak emission spectra decay over the first 1.5 μs. The spectra of plasma at different position were measured in the directions both perpendicular and parallel to the laser propagation respectively. And the spectra of laser-induced air plasma produced by different focal length lens were compared. The affection of different focal length lens for the plasma was described. The shapes of horizontal directions were smaller with the shorter focal length and the intensities of the plasma were higher. In addition, the temperature of plasma was evaluated from the emission intensities. The peak temperature was more than 10000K.

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