D. D. Malyuta

Multidimensional dynamics of laser-ablated materials

We experimentally investigated the expanding CO2 laser produced carbon plasma interaction with a substrate and the interactions occurring when two laser produced plasmas collide. The electron density and temperature of the single plasma source were measured and ion composition of plasma was determined by means of optical spectroscopy. The carbon dimers were observed near the target and substrate surfaces and during the collision of two plasmas.

Structure, dynamics and optical properties of multicomponent plasma produced near a surface by pulsed CO2 and excimer lasers

Results of the experimental studies of dynamics and optical properties of laser-induced plasmas are presented. Lasers with microsecond pulse width at (lambda) equals 0.308 and 10.6 micrometers were used. Spatially and temporally resolved plasma emission spectroscopy and laser beam absorption measurements were used to reveal plasma plume structure. It has been shown that in the case of low absorption at the plasma front, a two component plasma is formed with gas plasma temperature above 3 eV and electron number density in both gas and target vapor plasma in the range 1018 - 3 (DOT) 1019 cm-3. Comparison of the experimental data with computer model predictions is presented.

Experimental and theoretical investigation of a pulsed laser utilizing the CF4 molecule

An experimental investigation was made of the characteristics of a pulsed CF4 laser at high pump power densities. A radiation intensity of 0.5 MW/cm2 was obtained at a frequency of 615 cm−1 when the pump power conversion efficiency was 12%. Calculations are made of the laser parameters using steady-state and complete models. It is found that two-photon processes may play a decisive role in the lasing mechanism. The feasibility of using amplifiers to improve the radiation power in the 16μ range is determined.

Displacement Of Molten Metal Under High-Repetition-Rate Pulsed Irradiation

The processes occuring due to high-pulse-repetition rate laser beam interaction with metals have been studied by now very poorly both theoretically and experimentally. In the same time, first high repetition rate (HRR) pulsed laser applications to materials processing attract some interest to such a study. The investigation of possible improvement, theof the cw-laser-induced processes by using cw and HR R lasers together is also prospective. The melt removal mechanisms studied both theoretically and experimentally are the subject of the present paper. The pulse approximation of hydrodynamical equations is valid to describe the molten metal motion generated by laser puls of 1-100 μs duration. Reasonable agreement between theoretical estimations of velocity and escape time of the melt and experimental data was achieved. High-repetition rate pulsed processing was also investigated. The model of deep penetration by a HRR laser is put forward. It explaines the greater penetration ability of a HRR laser as compared to the cw laser of the same output power.