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A brief description of measuring means, a free-oscillation setup with a transverse sting of the model, and test conditions is reported. A procedure for processing experimental data is described. Quasi-steady and damping aerodynamic characteristics of the pitching moment of the model in the range of Mach numbers M = 1.75–6 are obtained. A comparison of research results with calculated data, as well as with the previous experimental data obtained using the base sting is given. It was found that at M = 3–6, regular undamped oscillations of the model are excited.

The model, experimental equipment, and test program are briefly described. A method of determining the aerodynamic characteristics of the model on the facility with free oscillations is presented. Aerodynamic derivatives of the pitching moment of the model are obtained for two positions of the axis of rotation and Mach numbers M∞ = 2, 4, and 6. At M∞ = 2, the model with the rear position of the axis of rotation is not balanced at low angles of attack, whereas irregular self-sustained oscillations of the model with the frontal position of the axis of rotation arise.

Anomalous behavior of the low-frequency elastic and anelastic properties of the ceramic PbMg1/3Nb2/3O3 was found by the inverted torsion pendulum within the temperature range corresponding to the diffused phase transition. This transition was also observed via dielectric measurements, which allowed finding the dielectric constant anomaly of the relaxor type.

An investigation was made of changes in the dissociation yield of UF6 molecules from pulse to pulse in the radiation field of a pulse-periodic CF4 laser. The energy per pulse was 25 — 130 mJ and the UF6 pressure was 0.3 — 0.6 Torr. The dissociation yield was proportional to the volume of the focused-radiation zone inside a cell where the photon energy density Φ exceeded the threshold value Φ0 throughout the investigated ranges of the energy per pulse and of the UF6 pressure. The first pulse dissociated 28% ± 3% molecules in this zone for Φ0=1 J cm-2 and 53% ± 5% of molecules for Φ0=1.5 J cm-2. A steep fall of the UF6 photodissociation yield from pulse to pulse was observed for the first time. An analysis was made of the processes which accompanied dissociation and estimates were obtained of the influence of the relevant reactions on the observed fall of the UF6 photodissociation yield from pulse to pulse.

Some design features and the parameters of the latest model of a pulse-periodic CF4 laser are reported. The working substance is circulated along a two-loop system and the temperature of an optical cell is stabilised automatically. The pumping is provided by a pulse-periodic TEA CO2 laser with an energy of 5.5 J per pulse in the form of the 9R12 line narrowed down to ~100 MHz by external injection of radiation from a low-pressure cw CO2 laser. The maximum radiation energy carried by a single CF4 laser pulse is 250 mJ and the average power at a pulse repetition frequency of 50 Hz is up to 6 W.

Since the advent of lasers, these unique sources of highly intense and monochromatic radiation have been proposed as excellent tools to induce or catalyze chemical reactions. Due to the great interest to the problem of isotope production, investigation and application, the laser method of isotope separation has received the most attention worldwide and may be the first major commercial application of lasers to chemistry. Laser methods of isotope separation are based on high selectivity and power of laser sources of radiation. One of the most prominent method is based on the effect is isotope-selective multiphoton dissociation of molecules by IR-radiation (MLIS-method). This phenomena was discovered in Russia in 1974 and developed from scientific investigations to industrial scale production of 13C isotopes in collaboration between the Kurchatov Institute of Atomic Energy, TRINITI and Institute of Spectroscopy of RAS. Demonstration facilities for sulfur and carbon isotope separation with average productivity up to 2 g/h have been created as a result of collaboration and these systems are aimed at optimization of MLIS process and evaluation of its cost efficiency. Experiments show that laser produced isotopes are far cheaper as compared to any conventional technique. Results of basic scientific research, existing technological cooperation allow to start building a laser isotope separation plant. Light element isotopes produced there can answer a wide variety of demands in many technologies. These isotopes can be readily used in medicine, agriculture, environmental monitoring, etc.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

An experimental investigation was made of the spectral dependences of the isotopic selectivity and of the dissociation yield of CH3SiF3 and C6H5SiF3 molecules interacting with CO2 laser pulses. The results indicated that collisional activation of the molecules played an important part.

There is a high worldwide interest in middle mass isotopes, particularly in carbon and oxygen isotopes. Over the few last years some industrial installations have been built for producing highly concentrated 13C isotope using the method of the low-temperature rectification of CO. However the cost of isotope manufacturing by this method is rather high. One of the ways to increase the output of middle-mass isotopes and to cut its costs is using laser technologies. This report is devoted to the development of the novel laser based technology for 13C isotope production.

Frequency locking of two TEA CO2 lasers in a common nonlinear element was achieved for the first time. The frequency locking arrangement was based on a four-wave interaction of light in SF6. The mechanism of nonlinear coupling between the CO2 laser resonators is considered.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A study was made of the kinetics of stimulated emission from two TEA CO2 lasers in a system with frequency locking by phase conjugation as a result of a four-wave interaction of light [V. Yu. Baranov, A. P. Dyad'kin, V. V. Likhanski? et al., Sov. J. Quantum Electron. 18, 1462 (1988)]. A simple method for ensuring two-pulse lasing with a variable time delay between the pulses in one gas-discharge chamber was proposed.