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12LM-PS-6
An analysis of the nonequilibrium ionization of silicon vapor under the influence of pulsed laser radiation
O. Koroleva1, V. Mazhukin1, A. Mazhukin1, E. Bykovskaya1
1Keldysh Institute of Applied Mathematics of Russian Academy of Sciences KIAM RAS, Mathematical Modelling, Moscow, Russian Federation
The development of numerous applications such as laser processing and surface structuring of materials, pulsed laser deposition (PLD) [1], laser-induced breakdown spectroscopy (LIBS) [2], and the production of nanomaterials make the study of the fundamental aspects of the theory of laser processes relevant.
The process of laser irradiation with matter combines a number of problems, such as energy release into the medium, its heating, phase transformations, ionization, accompanied by gas-dynamic phenomena in the evaporated substance and the resulting plasma. Plasma development is closely related to the processes of nonequilibrium kinetics, and the transfer of laser and intrinsic radiation in a line-like and continuous spectrum. Despite years of research, the kinetics of the emergence and development of plasma near the irradiated surface of a solid, the dynamics of the formation of a plasma plume have not yet been fully investigated [3].
Optical destruction of evaporated material near the surface of a solid target is a combination of processes that lead to a qualitative change in the gaseous medium of its properties. The medium changes from a state of partially ionized gas, completely transparent to the incident radiation, to a state of complete ionization, which absorbs laser radiation intensively. Therefore, optical breakdown, which constitutes the initial stage of the rapid formation of a laser plasma, is the subject of special attention and thorough research.
In the present work, optical breakdown in silicon vapor under the influence of laser radiation in the wavelength range X = 0.8 ^ 1.06 p,m is considered. The study of the mechanisms of optical breakdown of silicon vapor, their interaction and change leads to the need to consider the kinetics of population of multilevel systems, the quantitative description of which requires the construction of appropriate kinetic models. To study the conditions and characteristics of optical breakdown, a complete collision-radiation model has been developed that describes the kinetics of nonequilibrium ionization of silicon atoms and ions by laser radiation. The model takes into account not only collisional-radiative transitions, but also the main photoionization-recombination processes. Accounting for the energy balance of the electronic and atomic-ion subsystems allows the model to be used to describe the optical breakdown in a wide frequency range. The development of a nonequilibrium plasma in the radiation field of an infrared laser is analyzed. Acknowledgements:
The work was funded by the Russian Foundation for Basic Research grant No. 19-07-01001. References
[1] R. Eason (ed.) Pulsed Laser Deposition of Thin Films (Wiley, Hoboken, 2007).
[2] D.A. Cremers, L.J. Radziemski, Handbook of Laser-Induced Breakdown Spectroscopy (Wiley, New York, 2006).
[3] V.I. Mazhukin, V.V. Nossov, I. Smurov, G. Flamant. Analysis of nonequilibrium phenomena during interaction of laser radiation with metal vapors. Surveys on Mathematics for Industry, 2001, 10 (1), 45-82.
