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Registration Number

0224U031573, 0122U001971 , R & D reports

Title

Modeling of processes stimulated by external influences on physical and biological objects and their control by optical sensors

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Head

Makarenko Oleksii V., Доктор фізико-математичних наук

Registration Date

17-05-2024

Organization

Taras Shevchenko National University of Kyiv

Description

A theoretical model and computable algorithms for its realization have been developed for the analysis of controlled laser-induced destruction of the surface, considering the influence of factors accompanying the destruction, namely, reflection and scattering losses by both the surface and the plasma. A detailed theoretical study of surface losses and their influence on the laser-stimulated formation of crater-type surface reliefs was conducted. Theoretical studies and numerical calculations were carried out on the example of silver. In the general case before the occurrence of destruction, optical losses are the sum of the reflection coefficient and the scattering coefficient. Therefore, the coefficient for scattering on surface inhomogeneities was found. The dependence of the reflection coefficient on temperature was obtained, as well as the dependence of the scattering coefficient on both the roughness radius and temperature. Reflection losses for metals are dominant, scattering losses are less significant. In materials with lower reflection losses, they can be compared. With the beginning of surface destruction, scattering losses arise in the plasma-gas phase and become dominant. An analytical expression was found for determining the period of time before the destruction beginning. This time significantly depends on the circumstances of reflection and scattering before the occurrence of destruction and must be considering when describing the actual destruction process. It is shown that when the critical temperature is achievement and the plasma-gas phase nascence, the optical loss coefficient can be expressed by pressure, not through temperature. The process of laser heating of various types of surfaces is considered. The obtained temperature expressions consider a wide range of processes accompanying the interaction of laser radiation with substance. T

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Naumenko Svitlana М.
Suprun Anatolii D.
Shmelova Liudmyla V.
Yampolskyi Andrii L.