Resonance fluorescence of laser-driven barium plasma

The kinetics of barium photoplasma upon absorption of laser radiation by atoms in the resonant transition at lambda = 553.5 nmis studied by numerical simulation. At resonance transition saturation, seed electrons are generated. They gain energy through the superelastic processes and cause avalanche ionization of the gas. The brightening of the medium begins. After the metastable levels of barium are quenched by electrons, the brightening changes to darkening. The numerical results explain the experiment from [J. Appl. Phys. 57, 4968 (1985)], where the darkening effect of barium vapor was first obtained. The second probe laser affected the barium resonance ion line at lambda = 493.41 nm and induced fluorescence. The limits of applicability of the optically thin medium model for diagnosing photoplasma are discussed. (C) 2021 Optical Society of America