Spatial Characterization of Laser-Induced Plasmas by Deconvolution of Spatially Resolved Spectra

The spatial characterization of laser-induced plasmas, including their temperature, electron density, and relative atom density, has been carried out by emission spectroscopy. The plasmas were generated with iron samples in air and argon at atmospheric pressure. An imaging spectrometer equipped with an intensified CCD detector procured spectra with spatial resolution. The plasma characterization was made at three temporal gates (2 -3, 5 -6, and 9 -11 (mu)s) to permit the plasma ’s evolution to be studied. A deconvolution procedure was developed to transform the measured intensity, integrated along the line of sight, into the radial distribution of emissivity. Temperature and electron density distributions were obtained under the assumption of local thermodynamic equilibrium and Stark broadening of the emission lines. The relative atom density distributions in the plasma of the Fe atoms arising from the sample and of the Ar atoms arising from the ambient gas were determined and evidenced an important interaction between the plasma and the surrounding atmosphere.