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The paper reports on experimental studies of the active medium gain in supersonic electric-discharge oxygen-iodine laser (DOIL) based on traveling mw discharge. The measurements have included: absolute concentration, yield, and energy efficiency of production of SO in pure oxygen and oxygen-helium mixes at an oxygen partial pressure 3 to 15 Torr. For the gas flow to get rid of atomic oxygen, both heterogeneous mercury oxide coatings of the tube walls and homogeneous additives to the work mix, such as nitrogen oxide, have been used. The active medium of DOIL was formed using a nozzle array of the type of ejector sized as 10a50 mm 2 . The singlet oxygen-helium mix was supplied through three rows of sonic cylindrical nozzles, while the iodine-carrier gas mix - through two rows of supersonic conical nozzles with a half-opening angle of 10°(arc). The gas-phase iodine was produced in a quartz cell filled with iodine crystals. Room-temperature iodine vapors were picked up with a carrier gas (nitrogen or helium) and thus delivered into the nozzle array. The active medium was investigated by the high-resolution laser diode spectroscopy approach that used the laser type Vortex 6025 purchased from New Focus, Inc. The laser medium gain factor was determined by the intra-cavity approach having a sensitivity about 1a10 -6 cm -1 . The static temperature of the medium was determined from the measurements of gain half-width. The gain of the active medium of electric-discharge OIL has been investigated. The DOIL in use was operating on a mix composed as O 2 :He=1:1 at a total pressure of 6 Torr and flowrate - about 1 mmol/s. With helium as an iodine carrier gas at a flowrate ~3 mmol/s, we have recorded a positive gain in the DOIL medium.

Experimental and theoretical studies of singlet oxygen excitation in traveling microwave discharge (TMW) are presented. Singlet oxygen O2(a1Δg) concentrations and atomic oxygen mole fraction have been measured for different pressures, input powers and distances from mw resonator. It was shown that a steady-state traveling microwave discharge with a coaxial cavity resonator could provide maximal O2(a1Δg) yield of 22% for 2 Torr of pure oxygen and 27-30% for He : O2 = 1:1 mixture. Developed two-dimensional (r,z) model for calculations of plasma-chemical kinetics, heat and mass transfer was used for simulation of processes in TMW discharge under study. Effects of gas pressure, gas flow rate and input power are studied and compared with experimental measurements of O2(a1Δg) concentrations and atomic oxygen mole fractions.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The paper reports on the experimental investigations into supersonic oxygen-iodine laser (COIL). Study efficiency results of the COIL unit driven by the singlet oxygen generator (SOG) with twisted gas flow (TA-SOG) are given for supersonic iodine- oxygen mixing at a broadly ranged singlet oxygen pressure and buffer gas flowrate. The measurements were performed for variations of the throat sizes and the positions of the iodine injection plane in supersonic nozzle part. The gas pressure at the input of the nozzle unit was varied from 50 to 150 Torr. The chemical efficiency achieved under optimal operational COIL conditions was 33%.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The paper describes experimental and theoretical investigations on tunable CO2-laser-assisted measurements of the composition and concentrations in multicomponent wake behind supersonic civil aircraft. An experimental facility based on a tunable CO2 laser and multipass cell is presented and results of experiments on determination of substances typical for civil aircraft wake (carbon and nitrogen oxides, ozone, water vapor, etc.) are given. The conditions characteristic of the aircraft wake are simulated. A possibility to perform real-time measurements of substances in question at a level of 80 ppb (80 billion-1) is demonstrated. Calculative models were created and results of generation and evolution of substances in question in a turbulent twisted flow are reported. A mathematical model and program code were validated for numerical simulations of two-phase turbulent flow in a single trailing vortex in initial stage of contrail generation behind supersonic aircraft. The work was carried out under the project #1477 supported financially by the International Scientific-Research Center, Moscow.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

First results of experimental and theoretical investigations related to an industrial application of oxygen-iodine laser (COIL) are reported. A developed calculative model determines a transmission factor of a laser emission at a set wavelength depending on the waveguide parameters, focusing system characteristics, and laser emission intensity angular distribution. Carried out investigations concerned with delivery of a laser emission power up to 1.6 kW via industrial quartz waveguides of 0.8- and 1 -mm- diameters and 3 and 10 meters long. It was shown that at optimal parameters of the delivery system the waveguide transmission is virtually independent of the diameter and bending radius and is equal to 0.90±0.02, which is in a good agreement with calculative results. The spatial distribution of the laser intensity at the waveguide input and output was measured. The far-field divergence at the 90%-level of the power was shown to increase approximately by 4 times when the laser emission is propagated through a quartz waveguide with a 800-mkm-diameter core and 3 m long.

The results of experimental and numerical-theoreticalsupersonic COIL study carried out at RFNC-VNIIEF in 1998-2000 are performed. The novel data concern our research into the twisted-flow SOG (TA SOG) performance. The experimental investigations of gas-dynamic and energy performance, chemical efficiency, and optical quality are reported and discussed for the supersonic COIL with the parallel-flow system of gaseous iodine and singlet oxygen mixing. Application of TASOG together with the parallel-flow mixing system was shown to allow high values of COIL operation. The peculiarities of numerical-theoretical model developed at RFNC-VNIIEF are discussed.

An experimental study of energy performances and chemical efficiency of supersonic COIL with twisted aerosol SOG and the parallel-flow system was made. An experimental supersonic COIL setup is present.

A mathematical model of oxygen-iodine laser is described. A numerical analysis of three alternatives of mixing is performed.

The numerical calculations of the gain and dissociation degree of molecular iodine in a supersonic COIL channel are reported for supersonic mixing of flows and 0.2-, 0.3-, 0.4- mm- height critical sections of nozzles profiled for Mach number 2.5 to 4.0.

A novel automatic output stabilized tunable CO2 laser has been developed providing a new quality level of investigations in the areas of atmosphere monitoring, active media diagnostics, spectroscopy, etc. The optimally designed and arranged laser is composed of sites and systems with reliable operational resources. Mean time till failure of the laser is 1000 h. About 0.3 cm-1 resolution of its high-Q and highly selective resonator allows extraction of most lines in sequence and hot bands without using a hot cell in the laser cavity. The laser is also distinguished among many other lasers by generating a high power (up to 50 W) at traditional lines and a great amount (near 160 totally) of sequence and hot lines (up to 10 W) in the 9 - 12 micrometers range which can be qualitatively changed in favor of sequence or hot lines by replacing some of the sealed-off active element or the whole set of them. Software and hardware developed for handling the laser operation offer the possibility to extract a needed set of lines in any succession and with a required run duration.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The paper presents the most important efforts in the Chemical Oxygen-Iodine Laser (COIL) research carried on at Russian Federal Nuclear Center VNIIEF and some of their results. In particular, they include experimental data on the laser generation output of subsonic COIL on the water vapor concentration in singlet oxygen, calculated generation values of a supersonic COIL having high singlet oxygen pressure at the nozzle inlet, and experiments with the twisted-aerosol- flow singlet oxygen generator (TASOG) for up to 100 Torr pressures. Requirements are discussed for the supersonic high- pressure COIL components, such as singlet oxygen generator and the system for singlet oxygen mixing with iodine.

The gains were measured for the lines in the traditional band 00 0 1-10 0 0, 00 0 1-02 0 0, in the second band of the 00 0 2-10 0 1 sequence, and in the hot band 01 1 1- 11 1 0 emitted by the active medium of an electric-discharge carbon-dioxide module. The experimental results were used in a generalized theoretical model to find the translation and vibrational temperatures and the concentration of the active molecules. The Fermi resonance between the 10 0 0 and 02 0 0 did not ensure a Boltzmann distribution of their populations under the conditions in the electric-discharge module. The degree of dissociation of the carbon-dioxide molecules in the discharge did not exceed 22% when the maximum input power density was near 6 W/cm 3 .

Studying the optimum performance of molecular lasers requires information.on active medium parameters. Those in case of laser are translational and vibrational temperatures T, T1 , T2, T3' , and lasing molecule concentration., n. Vibrational temperatures have previously been determined in series investigations of electro discharge CO—laser active medium234S. But definition of concentration n potentially associated with large errors due to lack of lower laser level's vibrational temperature T1 measurements. Other temperatures have been estimated according to approximate model. As it was theoretically shown6 , to determine the inverse medium parameters without simplification, one should measure the small signal gains for lines of (0001_1000) and (0001_0200) traditional CO2 bands, (0002_1001) second sequence band and (O1'l-ll'O) hot band. Translational and vibrational temperatures and lasing molecule concentration were defined for CO—laser using the small signal gain measurements and theoretical scheme6.