Search

Experimental and theoretical investigations were made of the active-medium gain and of the parameters of the radiation emitted by an rf-pumped slab CO2 laser. The average output power was 160 W and the efficiency was 10%. Near-diffraction-limited divergence was achieved. In the pulse-periodic regime, the pulse power was twice the average power in the cw regime. When external correcting optics was used, the total divergence of the laser radiation was 2–3 mrad at 0.8 of the total power. A suite of programs for numerical simulation of the physical processes in an rf-pumped slab CO2 laser with diffusion cooling was developed. The experimental and theoretical results were compared.

Glucose enthalpies of solution in binary systems N-methylmorpholine N-oxide monohydrateaprotic solvent at 75°C are measured.

The influence of aprotic cosolvents dimethyl sulfoxide, dimethylformamide, and dimethylacetamide on interaction of N-methylmorpholine N-oxide with cellulose was studied.

The capability of cationic dyes in which the onium group is not conjugated with the chromophore system to form aqueous dispersions in a weakly alkaline medium was examined. Such dyes can be fixed on a fiber in increased amounts owing to their binding not only in the cationic form but also in the hydrolyzed monomolecular form.

Output characteristics of a planar RF-excited waveguide CO2 laser with 1 50W output power is investigated, including the divergences in stable and unstable directions, and influences of mirror misalignment and resonator length variations on the output power and mode structure of the radiation.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The paper presents the new concept for radiation mode selection, based on the spatial filter system, which disposed onthe electrode surface of slab CO2 laser. The results of the computer simulation and the experiment are discussed.Keywords: slab laser, intra-cavity mode selection. 1. INTRODUCTION Conventional RF-excited CO2 laser includes a pair of elongated metal electrodes, which planar surfaces are polished and highly reflectant. Two electrodes both reflect and guide the laser radiation along the slab-coordinate Along the wide-coordinate the beam propagates as in free space [1]. There are a few reasons to arise the higher ordermodes of radiation in slab laser. The main reason is an inadequate matching of the radiation wave front with the mirrorcurvature. As known, the discharge gap butt-end selects the mode structure [2]. The paper considers the method of thespatial filtration of the mode structure inside the resonator cavity of the slab laser [3]. 2. NUMERICAL SIMULATIONAND EXPERIMENTS.

For the various pumping rates and for the various heights of the gap were calculated the average value of the small- signal gain and its profile across the gap. For the high power slab CO2-lasers, RF-excited at 40.68 MHz, were analyzed the ranges of their geometry parameters vibration, providing for the possibility of diffraction limited performance. In theory and in experiment was shown the possibility to select the basic waveguide mode of radiation.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The paper presents the results of measuring of the small-signal gain in the active medium of the high-power pulserepetitive RF-excited slab C02-laser. The measurements were carried out for the pumping pulse durations in the range 20.50 Ls and pulse repetition rates 100.500 Hz. The maximal specific energy, delivered to the active medium, was 430 W/cm3. In the experiment were measured the average output power of radiation, pulse energy and power and the output beam divergence.

The compact sealed-off RF-self-excited slab CO2 laser has been developed. The average output power in pulse- repetitive mode of operation is controlled in the range of 20 - 200 W. The maximum pulsed power exceeds 400 W. The divergence of laser radiation is close to diffraction limit. The weight of the laser-head and RF-power supply is in total 40 kg.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Research and development of pulsed-repetitively slab rf- excited carbon-dioxide laser is presented. The experiments were carried out for two modes operation: meander mode (duty factor delta equals 50%) and pulse repetition mode at delta equals 12.5%. The range of 240 divided by 4000 Hz of pulse repetition frequency was used. Pulse power about 400 W for meander mode and up to 700 W for the second mode have been obtained. Input power, radiation pulse shape and output beam divergence were measured.

Results of experimental investigations of output power and beam divergence for a slab waveguide rf-excited carbon- dioxide laser are presented. Laser output power 150 - 250 W and maximum efficiency 10 - 13% in a beam with near- diffraction-limit divergence has been achieved. In repetitive-rate mode, the pulsed power was more than twice as much as the average one in the cw mode. After beam shaping lens, the sum beam divergence of 2.5 mrad at the 0.8 total power level has been obtained.

Results of investigations of a slab waveguide rf-excited carbon-dioxide laser are presented. Laser output power of range 200 W and efficiency about 10% in a beam with near-diffraction- limit divergence has been achieved. In the repetitive-rate mode, the pulsed power was more than twice as much as the average one in the cw mode. After beam shaping telescope, the total beam divergence of 2 - 3 mrad at the 0.8 power level has been obtained. A codes package of computer simulation of cw slab rf-excited diffusion-cooled carbon-dioxide laser was created. Comparison of calculated and experimental data has been fulfilled.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Peculiarities of constructing adaptive optical systems for forming and transportation of laser radiation through the atmosphere are considered. Results on elaboration and testing of the elements and the adaptive schemes on the special test-bench are given. The results on investigation of real-time compensation of the atmospheric phase disturbances using the adaptive optical train with the heterodyne wavefront analyzer, the electro-optical phase corrector, and the data-processing system based on the neural network are also reported. We analyze possible means of construction of adaptive optical trains to one-channel laser radiators and multi-channel phased systems.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Results of investigations of output power and beam divergence for a slab waveguide rf-excited carbon-dioxide laser are presented. Laser output of range 200 W and efficiency about 10% in a beam with near-diffraction-limit divergence has been achieved. In the repetitive-rate mode, the pulsed power was more than twice as much as the average one in the cw mode. After beam shaping telescope, the total beam divergence of 2-3 mrad at the 0.8 power level has been obtained.

In the present paper, theoretical and experimental studies of formation and transportation of radiation of a high-power repetitive pulsed CO2 laser in the optical system and along the 0.5 km horizontal atmospheric path have been performed. As is shown, the use of a light- guide, cooled metallic optics and adaptive system in the telescope provides efficient delivery of the high-power radiation.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Quantum-chemical calculations on molecular complexes containing ions and molecules of various solvents are used widely for studying the behavior of electrolyte solutions and for elucidating the properties of structures which form in them. Both nonempirical (ab initio) [1-14] and semiempirical methods [15-21] are used for these purposes. Ab initio methods, within the limits of the self-consistent field Hartree--Fock (SCF HF) approximation, give correct results for the equilibrium distances and formation energies of molecular complexes. For example, the formation energies of hydrates of Li +, Na +, K +, CI-, and Fcalculated in [1-3] agreed with experimental data [22] within limits of 1-2 kcal/mole. Numerous calculations of hydrogen bonds [9-14] also confirm the applicability of the HF approximation for studying interactions between polar molecules at distances up to 5 ~.

An experimental investigation was made of the characteristic features of the emission of a photodissociation laser with a resonator containing a telescopic angular selector. A method for aligning this resonator was developed and a study was made of the influence of misalignment of each of the resonator elements. The energy losses were found to correspond to the losses in the equivalent plane-parallel resonator. The advantages of the resonator employed was the maintenance of the angular width and direction of the maximum in the spatial distribution when a wedge deformation appeared in the resonator. The axial brightness was considerably higher than in the equivalent misaligned plane-parallel resonator without a selector.

We propose a modified Monte-Carlo method for studying the solvation of ions in a mixed solvent. We include two-particle shifts in the algorithm along with oneparticle shifts. Some of the two-particle shifts end with exchange of adjacent molecules. We have carried out calculations for the system Na+-N1·H2O-N2·MeOH for N1=N2=6 and N1=N2=9. We have concluded that there is preferential hydration of the Na+ ion in an equimolar water-methanol mixture.

The formation of cellulose-nickel nanocomposites has been studied by WAXS, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and scanning electron spectroscopy. Changes in the experimental conditions make it possible to widely vary the size of nickel and its oxide nanoparticles in the bulk and on the surface of cellulose fibers and to monitor the localization of these nanoparticles with the structure of cellulose remaining unchanged. The use of cellulose allowed preparation of nickel nanoparticles stabilized in the matrix.

1. We have determined the following thermodynamic characteristics of tert-butyldifluoroamine: heat of combustion (713±0.6 kcal/mole), standard enthalpy of formation (−52.9 ±0.6 kcal/mole), heat of evaporation (6.9±0.2 kcal/mole), and heat of formation in the gas phase (−46.0 ±0.8 kcal/mole). 2. From the thermodynamic data on the heats of formation of the ter-butyl and NF2 radicals, we assessed the C-N bond energy in tert-butyldifluoroamine.