Oxygen spectral lines for diagnostics of atmospheric laser-induced plasmas

In the present study OI spectral lines are measured, tested, and developed for diagnostics of laser-induced plasma experiments in air. The plasma plume was generated by the interaction of a 6-ns 750-mJ Nd:YAG laser at the fundamental wavelength of 1.06 A mu m with a standard Al target of known elemental composition in air. The emitted spectrum was in the range 200-1000 nm and was recorded using an Echelle spectrograph equipped with a time-gated ICCD camera. The measurements were performed at several delay times (0-10 A mu s). Based on LTE assumption, the excitation temperature is derived using a Boltzmann plot of OI emission lines. The FWHM of the Stark broadened OI line at 844.65 nm is used for electron density measurements at different times.