Temporal and Spatial Variations in Electron Density and Blackbody Temperature in the Initial Phase of a Laser Ablation BN Plasma

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Optical emission spectroscopy was used for examining the temporal variations in the spatial distributions of the blackbody temperature and electron density of plasmas produced by laser ablation of a BN target in ambient nitrogen gas. The blackbody temperature was estimated by fitting the continuum component in the optical emission spectrum using the Planck's law of radiation, and the electron density was evaluated from the Stark broadening of a line emission of a B atom. The blackbody temperature was evaluated to be close to 10⁴ K and the electron density was on the order of 10¹⁷- 10¹⁸ cm^-3, immediately after the irradiation of the laser pulse on the target. The dynamics of the blackbody temperature and the electron density were understood by considering plasma expansion and the confinement effect of ambient gas.