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%.
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.
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.
°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.
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.
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%.
The historical ejector-like chemical oxygen iodine laser (COIL) contribution at the Lebedev Physical Institute, Samara Branch is briefly presented. Two possible schemes of such COIL which provide the high exhaust pressure are considered. The high-pressure hot driver nitrogen is carrier of iodine vapor in the first scheme. In the second version the additional nozzles with the low-pressure secondary nitrogen are employed for injection iodine vapor but the pure high-pressure driver nitrogen has the room temperature. The last COIL version was investigated in Lebedev Physical Institute in more detail and results of these investigations are presented. This ejector nozzle bank generates gain medium with high Mach number, low temperature and high gain. A high chemical efficiency up to 25% and the potential pressure recovery up to 90 torr have been achieved simultaneously.
Experimental lasing results for the Chemical Oxygen Iodine Laser, (COIL), using four different ejector nozzle configurations are presented. These nozzle banks differed in the location of Iodine injection, the area of the oxygen nozzles, and the nozzle contour of the primary driver nitrogen. The aerodynamic choking of the oxygen jets caused by the under expanded primary driver nitrogen resulted in a reduction of the O2 (1(Delta) ) yield and chemical efficiency. Dilution of chlorine with helium in the ratio of 1:1 reduces the partial pressure of oxygen and increases the velocity resulting in a chemical efficiency of 25% at 250 mmoles/sec and 23% at 500mmoles/sec of driver nitrogen respectively. The corresponding Pitot pressures are 50 and 90 torr.
The developed supersonic COIL with 5 cm gain length was driven by Verti Jet SOG having 0.28 liter of working volume. The oxygen was diluted by the primary nitrogen downstream from the JSOG. Two types of nozzles were tested: single throat nozzle with 10 mm throat height and double throat height 15 mm. The COIL with single throat nozzle operated at the primary nitrogen dilution O2:N2 equals 1:1 and the chlorine flow rate less than 40 mmole/s to maintain the designed gas flow conditions in the reactor of JSOG. The maximum power 765 W has been achieved at 39 mmole/s of the chlorine molar flow rate. The using of double throat nozzle allowed to increase chlorine moral flow rate up to 75 mmole/s. In this case the maximum power 1.4 kW has been reached for primary nitrogen ratio O2:N2 equals 1:1.28. The specific performance so f 5 kW per 1 liter of the reactor volume, of 100 W/cm2 per unit of the stream cross section are in the cavity and of 2,7W of the pump capacity were obtained.
The axial flow COIL is a convenient device to study the gain and storage energy life-length along the gas flow. When the velocity of the axial flow close to the sonic velocity and the active medium is preliminary cooled the conditions like in the supersonic transverse flow COIL can be realized. The presented axial flow COIL was driven by jet type SOG. The next gas flow rates were used in all experiments: 20 mmole/s of the primary buffer gas, 10 mmole/s of secondary buffer gas and 10 mmole/s of chlorine through the jet SOG. The maximum output power 106 wt was obtained at ~0.05 mmole/s of the iodine flow rate with primary and secondary nitrogen buffer gas. The cooling of the primary nitrogen to 80°K resulted in 130 wt output power. The using helium at 80°K instead of nitrogen resulted in 186 wt output power or 20.5% total chemical efficiency for 0.1 mmole/s of the iodine flow rate. The exposition of the laser beam at the black wood target showed that the main part of laser power was inside the circle 22 mm in diameter.
The chemical oxygen-iodine laser (COIL) is a scaleable high power laser promising for industrial applications. The principles of singlet oxygen generation in the jet type singlet oxygen generator and COIL operation are considered. The progress in high pressure jet type singlet oxygen generators allowed to develop the compact highly efficient COIL. The different types of efficient mixing schemes were tested in COIL based on the high pressure jet singlet oxygen generator. The preliminary cooling of active medium via mixing of oxygen with cold buffer nitrogen gas result in high efficiency operation of the small scale COIL with subsonic gas flow in the laser cavity. The project of COIL with high pressure of oxygen in laser cavity is discussed.
The experimental results of study of sub- and supersonic chemical oxygen-iodine lasers (COIL) based on the jet type singlet oxygen generator are presented. The progress in the high pressure jet type singlet oxygen generators allowed to develop the compact highly efficient COIL. The different types of the mixing schemes were tested in supersonic COIL based on the high pressure jet singlet oxygen generator. The preliminary cooling of the active medium by mixing of oxygen with the cold buffer nitrogen gas results in high efficiency operation of the small scale COIL with subsonic and supersonic gas flow in the laser cavity. In COIL with the fast axial gas flow the chemical efficiency more than 20% was achieved.
Five major methods of preparing active medium in supersonic COIL are analyzed: (1) `classical' case with upstream SOG primary buffer gas and chlorine premixing, injection and dissociation iodine vapor in the subsonic region of the supersonic nozzle; (2) mixing oxygen stream with primary buffer gas (may be cooled) downstream of SOG; (3) iodine vapor injection into boundary layers of the trans-sonic region of the small-scale grid nozzle; (4) mixing of the coflowing supersonic jets of pure oxygen and N2 + I2 mixture at close static pressures and Mach numbers; (5) mixing of co-flowing sonic (or supersonic with small Mach number) pure oxygen jets and high velocity head supersonic N2 + I2 jets for reaching very high active medium recovery pressure.
Experimental investigation of a jet singlet oxygen generator for a supersonic chemical oxygen-iodine laser was performed aimed to evaluation of the effects of BHP temperature and composition on the water content and other output generator parameters. Laser experiments on a small-scale system were realized to prove the obtained results.
The increasing of stagnation pressure and Re number of gas flow is a very important for supersonic oxygen-iodine laser (COIL). This goal can be achieved with the aid of high pressure singlet oxygen generator (SOG) and high dilution of oxygen with buffer gas of high molecular weight downstream of SOG. The study of COIL operated with jet type SOG at 10 and 20 mmole/s of chlorine flow rate and 50 torr output of pure oxygen is presented. Two experimental set-up were tested. In the first one the mixing of chlorine with buffer gas was provided upstream of SOG gas inlet. In the second one the pure chlorine was injected into SOG and oxygen was mixed with buffer gas downstream of SOG outlet. The stability of jet SOG in the first set-up strongly depended on partial buffer gas pressure and its molecular weight: at higher pressures and molecular weight the stability of SOG operation was worse. In the second set-up the operation of SOG didn't depend on buffer gas pressure and its molecular weight. COIL output power was highest for first set-up with dilution of chlorine by buffer gas until SOG stable operated. In the second set-up the output power was in twice less and strongly depend on type and position of buffer gas injector between SOG and iodine injector. This dependence strongly demonstrated the importance of gas mixing to molecular level for achieving highest COIL power. Another problem considered in this work is connected with BHP heating that important for recirculation of liquid in long time duration COIL operating system. The correlation of BHP heating and O2(1(Delta) ) yield is presented. It is shown that nacsent O2(1(Delta) ) yield is close to 100%.
Development of the high pressure singlet oxygen generator (SOG) is a very important aspect for chemical oxygen-iodine laser (COIL). Increasing of oxygen pressure up to 30 torr and more at conserving high O2(1(Delta) ) yield and maintaining BHP temperature at minus (10 divided by 20) degrees Celsius permits us to decrease ration [H2O]/[O2] to 5% and less. In this case COIL can operate successfully without a water vapor trap. With raising the total pressure Reynolds number increases too, diminishing boundary layers in supersonic nozzles and improving pressure recovery. The weight and dimensions of the SOG and laser become reduced for the same gas flow rate. For solving these problems the jet SOG has been suggested and developed in Lebedev Physical Institute, Samara Branch. The advantages of the jet SOG consist of the following: (1) Large and controlled specific surface of contact liquid-gas provides for high mass transfer efficiency. (2) High jets velocity guarantees fast basic hydrogen peroxide (BHP) surface renovation. (3) High gas velocity in the reaction zone diminishes O2(1(Delta) ) quenching. (4) Efficient gas-liquid heat exchange eliminates the gas heating and generation water vapor due O2(1(Delta) ) quenching. (5) Counterflowing design of the jet SOG produces the best conditions for self-cleaning gas flow of droplets in the reaction zone and gives the possibility of COIL operation without droplets separator. High pressure jet SOG has some features connected with intrachannel jet formation, free space jets reconstruction, interaction jets ensemble with counter moving gas flow and drag part of gas by jets, disintegrating jets, generation and separation of droplets, heat effects, surface renovation, impoverishment BHP surface by HO2- ions, moving solution film on the reaction zone walls, etc. In this communication our current understanding of the major processes in the jet SOG is set forth. The complex gas and hydrodynamic processes with heat and mass transfer, chemical reactions, generation of the relaxing components with high energy store take place in the SOG reaction zone. It is impossible to create a sufficiently exact model of such a jet SOG taking into account all the enumerated processes. But some approximations and simplifications allow us to determine what the main jet SOG parameters parts are for designing COIL.
Jet singlet oxygen generator (JSOG) is one of the most efficient sources of electronically excited O2(1(Delta) ). The JSOG can operate at very high partial O2(1(Delta) ) pressure. This feature of JSOG allows supersonic COIL operation without water vapor trap. The prediction of output parameters of JSOG is very important for correct design and engineering of COIL. The one-dimensional model of JSOG has been developed to predict output parameters (chlorine utilization, O2(1(Delta) ) yield). The comparisons of calculated and measured output parameters are presented. The main attention is paid to discrepancies of calculated and measured output parameters and limitation of the one-dimensional model. It is shown that for extremely high pressure JSOG the role of effects that cannot be included into a one-dimensional model is very important. The difference between input and output BHP temperature in JSOG is correlated with chlorine utilization and O2(1(Delta) ) yield.
An unstable resonator with semitransparent output coupler (NRPOZ) and low magnification is investigated theoretically and experimentally for Fresnel numbers 5 - 15 and small signal gain 0.5 - 2.4. With the help of numerical simulation the condition of minimum diffraction losses is found. The beam divergence in the dc-discharge transverse-flow kilowatt-power CO2 laser was approximately two times less in comparison with telescopic unstable resonator without substantial loss of mode volume and output power.