A L Petrov

Laser-controlled synthesis of nickel-aluminum intermetallic compounds

Laser-initiated self-propagating high-temperature synthesis (SHS) in a disperse Ni-Al powder composition was studied. The X-ray diffraction measurements reveal the presence of nickel-aluminum intermetallic phases, the relative content of which depends on the regime of laser action. The regimes making possible a laser-controlled SHS of Ni-Al intermetallic compounds are considered.

Laser-beam pattern cutting of carbon-based composites

The possibility of using laser radiation for pattern cutting of sheet carbon-based materials is analyzed. It is theoretically justified and experimentally demonstrated that continuous-wave laser radiation can be efficiently used only for pattern cutting of carbon-based plastics and carbon-carbonaceous composites with a thickness of up to 1.5 mm. For laser-beam pattern cutting of carbon-based composites of larger thickness, the use of pulse-recurrent radiation with high pulse-repetition rate in the multipass-cutting mode is promising.

Changes in the structure and surface properties of carbon-carbon composites under the action of laser radiation

The influence of laser radiation on structural and other properties of carbon-carbon composites with fillers composed of TKK-2, Ural T-22, and TNU-4 carbon fabrics was studied. It is shown that the processes occuriing in the above materials under significantly nonequilibrium conditions of high-rate laser-induced heating to ultimate temperatures of carbon sublimation lead to global improvement in the performance of these materials.

A gas-dispersed medium for pulsed chemical lasers based on photon-branched chain reactions

A gas-dispersed medium (aluminum particles in argon) was obtained for the first time with the parameters necessary for the development of pulsed chemical lasers based on photon-branched chain reactions: particle size, 0.1–0.15 μm; particle density, >108cm−3; argon pressure, 0.3–1.5 atm; medium lifetime, >10 min.

Determination of Absorption and Scattering Coefficients of Laser Radiation in Biological Tissue

Low intensity lasers are widely used for therapeutic medicine. Therapeutic devices based on semiconductor lasers emitting in red and near IR-region are particular popular. Specifically, in Samara State Medical University the authors had collected a significant experience of the treatment of vessel diseases and liver ones by mean of low intensity laser radiation [1]. This experience includes good results on chronic virus hepatitis treatment [2]. But empirical application of lasers in medicine leaves behind its experimental and theoretical ground. The information about light propagation in biological tissue is very important for tissue diagnostic as well as for laser radiation dosimetry. This information is necessary to determine mechanism of therapeutic effect and to give scientific ground for treatment methods to make them more effective.

Electric-discharge CO2 laser with a vortex gas flow

The operation of a cw electric-discharge CO2 laser, using a glow discharge in a gas stream set into a swirling motion in a vortex tube to create the active medium, was investigated experimentally. The cooling of the active zone was shown to be of the same nature as that in a diffusively cooled laser. Turbulent heat conduction contributed in addition to molecular heat conduction in removing heat from the active region of the discharge. The energy characteristics per unit length were a factor of 2–2.5 higher than those of a diffusively cooled laser. A stable glow discharge in air at a pressure of 200 Torr was also realized. Current densities above 1 A/cm2 and a specific input energy of greater than 800 J/liter were achieved for a discharge in a CO2:N2:He = 1:3:7 gas mixture at a pressure of 37 Torr.

Relaxation of the energy stored in an oxygen–iodine active medium containing bound iodine

A study was made of the kinetics of an oxygen–iodine medium containing bound iodine. The evolution of the energy stored in the active medium under the influence of quenching during the dark stage of the preparation was determined. A theoretical investigation was made of the time dependences of the concentration of singlet oxygen and of the gain in the process of accumulation of atomic iodine in mixtures containing CH3I, C3F7I, and CF3I. Universal time dependences were obtained for mixtures with high concentrations of water vapor. The results of the calculations should be useful in the selection of the parameters of the initiating pulses employed in an oxygen–iodine laser containing bound iodine.

Generation and amplification of nanosecond pulses by iodine lasers

Results are reported of experimental investigations of high-power photodissociation iodine laser pumped by lamps and by radiation from high-current electric discharges. The basic parameters of the working medium, the parameters of both lamp-pumped and discharge-pumped lasers, and methods of shaping of a short pulse with diffraction directivity of the radiation are investigated. The possibility of effective amplification of a short pulse by an iodine amplifier pumped with an open high-current discharge is demonstrated. An iodine laser generating a pulse of duration I nsec, divergence 10-4 rad, and energy 100 J at a contrast 108 and 300 J at a contrast 102–103 is described.