Laser-induced breakdown spectroscopic characterization of tungsten plasma using the first, second, and third harmonics of an Nd:YAG laser

Tungsten has become an important material in fusion reactors and plasma-facing components. Laser ablation of tungsten has been carried out at 1064 nm, 532 nm, and 355 nm at atmospheric pressure to determine the capability of laser-induced breakdown spectroscopy (LIBS) for in situ diagnosis of plasma-facing components. Stark broadening and Boltzmann plots were used for the measurement of electron density and temperature, respectively of laser produced tungsten plasma. At a constant laser irradiance (1.05 × 10¹⁵ W m^-2) the maximum temperature (16,304 K) was reached at 1064 nm. Maximum electron density (1.12 × 10¹⁸ cm^-3) was observed at 355 nm. Variations in electron temperature and density as a function of laser irradiance and time are also discussed. This work could provide important reference data for the design and optimization of LIBS systems involved in plasma-facing components diagnostics.