Valery D. Nikolaev

Efficient chemical oxygen-iodine laser powered by a centrifugal bubble singlet oxygen generator

Efficient production of singlet delta oxygen in a bubble singlet oxygen generator (BSOG) under the influence of centrifugal acceleration, 136g, has been obtained. An output power of 770W with chemical efficiency of 25.6% has been achieved in a small-scale, supersonic chemical oxygen-iodine laser supplied by the centrifugal BSOG. The ratio of the output power to the basic hydrogen peroxide volumetric flow rate was 4.3KJ∕liter. Efficient chemical oxygen-iodine laser (COIL) operation with the centrifugal BSOG demonstrates the potential for mobile COIL applications.

High gain, high pressure, highly efficient COIL

The activity of development a COIL with high potential recovered pressure, high gain and efficiency is described. Two nozzle banks with conical supersonic nozzles for the driver nitrogen but with different nozzle arrangements have been developed for generation of the gain flow of chemical oxygen-iodine laser. The nozzle banks were supplied by oxygen flow from the cross-flow singlet oxygen generator with filament-guided jets. Results of aerodynamic tests, visualization of flows by laser induced fluorescence, scanning of the excited iodine atoms distribution and laser power extraction are presented. The efficient penetration of the driver buffer flow into the gain flow was observed at distances less than 100 mm from the nozzle banks. The total power exceeding 1 kW with chemical efficiency more than 24% was obtained in 5 cm gain length COIL without helium dilution. The lasing was observed for both nozzle banks at total mirror transmission more than 10%.

Ejector COIL with supersonic nozzles for driver N2

Experimental results of investigation of the ECOIL with supersonic nozzles for driver N2 are presented. Employment of the supersonic nozzles and extremely high-pressure driver nitrogen gives possibility to minimize the plenum oxygen pressure at high oxygen flux, to reach high gain and chemical efficiency.

Performance of high pressure COIL with centrifugal bubble singlet oxygen generator

A centrifugal bubbling SOG is a perspective source of oxygen at high pressure with high depletion of the BHP in the single burn dawn. The theoretical estimations show that at high centrifugal acceleration gas-liquid contact specific surface 30cm-1, frequency of the surface renewal can less than 10-3s and bubble rise velocity up to 500 cm/s be realized in the bubble SOG. The results of the measurements of O2(1&Dgr;) yield, chlorine utilization and water fraction at the exit of the centrifugal bubble SOG are presented. A high O2(1&Dgr;) yield and chlorine utilization higher than 90% have been obtained at chlorine gas loading up to 6 mmole/s per 1 cm2 of the bubbler surface. The ejector COIL powered by centrifugal bubbling SOG demonstrated ~25% of chemical efficiency with specific power 6 kW per 1 litre/s of the BHP volumetric rate.

Efficient COIL driven by SOG with filament-guided jets

°The cross-flow SOG with filament-guided jets (FJSOG) was developed for COIL. It was found that chlorine utilization strongly depended on chlorine molar flow rate and BHP volumetric rate, and slowly depended on the working pressure for fixed chlorine molar flow rate. The increase of BHP temperature from -25°C to -7C resulted in the increase of chlorine utilization and water vapor fraction in the gas flow from FJSOG. The supersonic COIL with ejector nozzle bank was supplied by oxygen flow from FJSOG. The FJSOG worked very stable without droplet carry out and in laser experiments the clogging of nozzles by dry deposit was not observed. The chemical efficiency more than 24% have been obtained in ejector COIL driven by FJSOG.

Supersonic COIL driven by centrifugal bubbling SOG with efficient depletion of chemicals in single pass

An efficient and compact centrifugal bubbling SOG was employed as energy source in supersonic COIL. A centrifugal bubbling SOG generated gas at 100 torr of total pressure providing 90% of chlorine utilization and 60% of O2(1Δ) yield with efficient depletion of BHP chemicals in single pass through SOG. A 1 kW class ejector COIL powered by this SOG demonstrated a specific power of 12.5 W per 1cm3/s of BHP volumetric rate at chemical efficiency 22.7%.

Perspective methods for the generation of COIL gain medium

An ejector nozzle bank powered by centrifugal bubbling SOG is considered like highly efficient gain generating system for COIL. A high potential recovered pressure ~100 torr of the gain medium flow with a small signal gain higher than 1% cm-1 and low oxygen plenum pressure has been demonstrated. A centrifugal bubbling SOG is an efficient source of oxygen at high pressure with high depletion of the BHP in the single burn dawn. A high 02(1&Dgr;) yield and chlorine utilization higher than 90% have been obtained at chlorine gas loading up to 6 mmole/s per 1 cm2 of the bubbler surface. The ejector COIL powered by centrifugal bubbling SOG demonstrated ~25% of chemical efficiency with specific power 6 kJ per 1 litre of the BHP in the single burn dawn. The combination of centrifugal bubble SOG with ejector nozzle bank can be considered as a promising gain medium flow generation system for COIL.

Advanced singlet oxygen generator and nozzle bank in traditional COIL technology

A centrifugal bubbling SOG generated gas flow with partial oxygen pressure up to 40 torr at singlet oxygen yield about 60% and residual chlorine less than 10%. At initial BHP temperature 260K and ratio of chlorine molar flow rate to BHP volumetric rate of 1mole/litre the output BHP temperature was 290K and water vapor fraction relative to the oxygen was 15%. An oxygen flux up to 6 mmole/s per 1 cm2 of the bubbler surface has been attained. An ejector nozzle bank generates gain medium flow at Mach number ~2 and temperature lower 200K with small signal gain higher 1%/cm. Ejector COIL powered by centrifugal bubbling SOG demonstrated ~25% of chemical efficiency with specific power 6 kW per 1 litre/s of BHP volumetric rate.

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.