喷射型单重态氧发生器性能研究

Three dimensional transient analysis of bubble dynamics in centrifugal bubble singlet oxygen generator for scalable COIL

A gas-sampling diagnostic has been developed to determine the molecular composition in real time of the gaseous flow emanating from a 1(Delta) g oxygen generator. This excited state oxygen is the energy source for a chemical oxygen-iodine laser (COIL). The major constituents in the flow, helium, oxygen, chlorine and water are drawn from the generator and transported to a quadrupole mass spectrometer for analysis. Information derived from this instrument such as chlorine utilization, water vapor content and flow impurities will advance our understanding of the oxygen generator performance. Precise measurements of water content are particularly important because of its energy quenching effect on I*, the lasing species in a COIL. This diagnostic may also be used to measure the mixing distribution of molecular iodine in the supersonic excited oxygen flow downstream of the nozzles. This paper discusses the criteria for the design of the gas-sampling diagnostic.

The generator of singlet oxygen (SOG) remains still a challenge for a chemical oxygen-iodine laser (COIL). Hitherto, only chemical generators based on the gas-liquid reaction system (chlorine-basic hydrogen peroxide) can supply singlet oxygen, O₂(¹Δ), in enough high yields and at pressures to maintain operation of the high power supersonic COIL facilities. Employing conventional generators of jet-type or rotating disc-type makes often problems resulting mainly from liquid droplets entrained by an O₂ (¹Δ) stream into the laser cavity, and a limited scalability of these generators. Advanced generator concepts investigated currently are based on two different approaches: (i)O₂(¹Δ) generation by the electrical discharge in various configurations, eliminating thus a liquid chemistry, and (ii) O₂(¹Δ) generation by the conventional chemistry in novel configurations offering the SOG efficiency increase and eliminating drawbacks of existing devices. One of the advanced concepts of chemical generator - a spray SOG with centrifugal separation of gasliquid phases - has been proposed and investigated in our laboratory. In this paper we present a description of the generator principle, some essential results of theoretical estimations, and interim experimental results obtained with the spray SOG.

Singlet oxygen generator is the key of chemical oxygen-iodine laser (COIL) which supplies energy for the system. However, the traditional generators have some drawbacks just as the bigger volume and the lower chemical efficiency. Specific surface area is the important factor restricting the development of singlet oxygen generator. Many researches on increasing specific surface area have been done to improve the performance of singlet oxygen generator. A new type eject singlet oxygen generator was introduced in this paper. Ejector was used in gas-liquid reaction. Liquid ejected through the nozzle with high velocity droved by high pressure, and gas ejected into mixing chamber along the tangent of nozzle. Gas and liquid were broken into many small droplets. Gas and liquid reacted in reaction chamber, then the mixture ejected into separator with very high speed. These droplets can produce mount of gas-liquid interface and increase the chemical efficiency of generator. Many numerical simulations have been done on the new type generator According to the simulations, eject singlet oxygen generator is feasible and has prospect. Therefore ejector may be a better type of singlet oxygen generator.

The singlet oxygen generator (SOG) generates singlet oxygen for a chemical oxygen iodine laser (COIL), using the gas-liquid reaction between basic hydrogen peroxide (BHP) and Cl2 gas. The Jet-SOG has been widely used, wherein jet BHP from small orifices reacts with Cl2 gas, and the BHP utilization is less than 1% in a single pass through the reaction zone. To improve BHP utilization, the reaction surface with Cl2 gas should be increased, and the droplet diameter of BHP should be decreased. In this study, two types of mist generators were tested for the SOG, with which 65-µm- and 15-µm-diameter droplets were generated. In the 65 µm mist generator, BHP utilization was 22.5% at the Cl2 flow rate of 8.3 mmol/s, and in the 15 µm mist generator, BHP utilization was 41.5% at the Cl2 flow rate of 9.0 mmol/s, that is, BHP utilization of the new SOG, Mist-SOG, markedly exceeded that of the conventional Jet-SOG.

Functional singlet oxygen generators based on phthalocyanines

The recent demonstration of gain and continuous wave power extraction on the electronic P1/2 to P3/2 transition of the I atom using NCl(a1∆) as the pumping species proving the viability of the all gas-phase iodine laser (AGIL), has brought with it the need for an increased theoretical understanding of this complex system. Multiple gas phase chemical processes occur in this system: the generation of Cl atoms with F atoms, the generation of I atoms with Cl atoms, the production of NCl(a1∆) with Cl atoms and HN3, and the pumping of I to the I(P1/2) state with NCl(a1∆). Each of these processes may be composed of multiple individual chemical reactions describing production and loss processes. And finally, this set of processes occurs within a flowing gas, with the exoand endothermicity of the reactions complicating the coupling of the chemical reactions to the fluid dynamics and vice-versa. The goal of this paper is to provide an overview of the current theoretical understanding of this complex system with respect to the numerous measured finite-rate chemical processes and the coupled fluid dynamic-diffusional mixing processes. 1-D explorations of the AGIL finite-rate chemistry mechanism including sensitivity studies are shown. 3-D NavierStokes simulation studies of reactant mixing are examined, and predictions made for conditions to improve mixing and reaction in AGIL device hardware. Confirmation of these predictions in results from recent AGIL power extraction experiments is shown. * Member AIAA. Introduction The development of chemical lasers begins with the demonstration of the first iodine laser by Casper and Pimentel who in 1964 demonstrated lasing on the electronic P1/2 to P3/2 transition of atomic iodine at 1.315μm by photodissociating alkyl iodide compounds. The high energy and high atmospheric transmission of this wavelength developed considerable interest in the chemical generation of the I(P1/2) state. With no known chemical reactions directly producing high concentrations of I(P1/2), interest shifted to the use of energy transfer reactions to generate this state. Derwent, Kearns, and Thrush postulated the use of the first electronic excited state of oxygen, O2(a 1∆), as the transfer agent. O2(a∆) being both metastable and near-resonant with I(P1/2) would provide a logical energy transfer species. McDermott et al provided proof of concept for this hypothesis, demonstrating a laser based on the O2(a 1∆) to I(P3/2) energy transfer and producing the first chemical oxygen-iodine laser (COIL). With the advent of COIL also came the realization of one of its’ primary drawbacks, namely the 2 phase chemistry required to produce O2(a 1∆). The basic hydrogen peroxide solution used during O2(a 1∆) generation constitutes a large fraction of the overall weight of the system and adds water vapor, a relatively strong deactivator of I(P1/2). In order to circumvent the deleterious effects of the 2 phase COIL chemistry, energy donors for I were sought that could be generated in the gas phase at high number densities. The nitrene metastables were recognized as possible replacements for O2(a 1∆) as energy donors, primarily due to their visibility from investigations into their use as agents for generating short wavelength chemical lasers. The isovalent electronic structures of NCl(a1∆) and NF(a1∆) with respect to O2(a 1∆), long lifetimes, and the ability to generate large number densities in the gas phase made NCl(a1∆) and NF(a1∆) likely candidates for iodine energy donors. Yang et al were the first to investigate NCl(a1∆) as an iodine energy donor, measuring the transfer rate and key deactivation rates subsequently followed by a measurement of gain on the I(P1/2) to I( P3/2) transition. Similarly, Ray and Coombe measured the transfer rate followed by a pulsed laser demonstration via pulsed photolysis of ClN3 and CH2I2. With the early work of Yang et al, and Ray and Coombe establishing the viability of an NCl(a1∆) based transfer laser, significant effort was spent on measurement of the key rates constituting the complex chemistry of supporting these experiments. Henshaw measured the temperature dependence of NCl(a1∆) quenching by I(P3/2), as well as rates for chemical generation of NCl(a1∆).20 Setser with co-workers 34th AIAA Plasmadynamics and Lasers Conference 23-26 June 2003, Orlando, Florida AIAA 2003-4310 This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States.

Simulation of chemical lasers such as the chemical oxygen-iodine laser (COIL) is of timely interest due to the recent acceleration of the airborne laser military development program and ongoing commercial development programs. As a contribution to these efforts, a 3-D COIL simulation model was developed based on the Computational Fluid Dynamics (CFD) code GASP which solves the conservative, finite-volume formulation of the full Navier-Stokes equations coupled to a new finite-rate, non-equilibrium chemistry model and a conservative, multicomponent molecular diffusion model. A 3-D simulation of the COIL flowfield was performed and compared to detailed species distributions measurements from experiment for the purpose of validation using a unique averaging technique developed to mimic the actual physics of the experimental gain measurement. These detailed comparisons demonstrate that the simulation model accurately predicts the experimentally measured distributions, a significant result in 3-D simulation of reacting flows. Additional results from the validated simulation include: development of new finite-rate COIL chemistry mechanism, evidence indicating the presence of H2O condensation in the COIL mixing nozzle, and evidence suggesting that the physical processes in the flow from the O2('A) generator are not completely understood.

Great success has been obtained in the R&D of a chemical oxygen-iodine laser (COIL) operating on the electronic transition of the iodine atom, which gets an excitation from the energy donor -singlet delta oxygen (SDO). The latter is normally produced in a chemical SDO generator using very toxic and dangerous chemicals, which puts a limit for civilian applications of COIL that is still a very unique apparatus. Totally new non-chemical SDO generator is needed to allow oxygen-iodine laser to achieve its full potential as a non-hazardous efficient source of high-power laser radiation. There was interest in producing SDO in electric discharge plasma since the 50's long before COIL appearing. The idea of using SDO as a donor for iodine laser was formulated in the 70's. However, the injection of iodine molecules into a low- pressure self-sustained discharge did not result in iodine lasing. One of the main factors that could prevent from lasing in many experiments is a rather high threshold yield approximately 15 percent at 300K, which is needed for obtaining an inversion population. An analysis of different attempts of producing SDO in different kinds of electric discharge plasma has been done which demonstrates that high yield at gas pressure of practical interest for modern COIL technology can be obtained only in non-self sustained electric discharge plasma. The reason is that the value of relatively low reduced electrical field strength E/N approximately 1E-16 V.cm 2 , which is an order of magnitude less than that for the self-sustained discharge, is extremely important for the efficient SDO production. Although different kinds of non-self sustained discharges can be used for SDO production, we got started experiments with e-beam sustained discharge in gas mixtures containing oxygen. High specific input energy up to approximately 3 - 5 kJ/ has been experimentally obtained. Theoretical calculations have been done for different experimental conditions indicating a feasibility of reasonable SDO yield. Experimental and theoretical research of self-sustained electric discharge in SDO produced in a chemical generator, which is very important for getting plasma-chemical kinetic data needed for an estimation of SDO yield, is also discussed.

Process designs were evaluated for the continuous, large-scale generation of singlet delta oxygen for use in a chemical oxygen-iodine laser. The excited singlet oxygen is generated from the chemical reaction of chlorine gas with basic hydrogen peroxide. The chemical reaction also produces a large waste brine stream that can be controlled by recycling through a chlor-alkali cell, which regenerates the reactants Cl2 and NaOH. To prevent deactivation of this excited oxygen, a large excess of hydrogen peroxide is typically used to change the reaction mechanism. This use of excess hydrogen peroxide or nonstoichiometric generation leads to substantial increases in capital and operating costs when compared with theoretical stoichiometric (no excess) generation. For the generation of singlet oxygen at a 500-kW level of equivalent lasing power, a theoretical stoichiometric plant producing all reactants has an estimated capital cost of $38 million. The capital cost for a nonstoichiometric plant is $98 million. Operating costs are $0.68 and $2.12/lb of singlet oxygen, respectively. The energy efficiency of generation is ∼6.3% for the theoretical stoichiometric flow sheet and 3.3% for the nonstoichiometric flow sheet. At this nonstoichiometric efficiency, the use of a chemical oxygen iodine laser for photoneutralization of negative ion beams is probably not competitive with other technologies below a 750-keV neutral beam level.

Chemical oxygen iodine laser (COIL) is the only laser expected to be applied for thick plate cutting, for instance, by high laser power over 5 kW transferred to the processing fields by the optical silica fiber. As a result of the first stage of industrial COIL development, a 1 kW subsonic COIL was delivered as a commercial processing device first in the world in 1992. The supersonic COIL development was carried out at the second stage and the output power of over 5 kW was obtained in 1995. Using this high power beam, superiority of the COIL as an industrial laser was studied by processing metals.

The spectroscopically measured lineshape of an atomic transition provides a wealth of useful information relative to diagnosing the state of a gas. The center of the lineshape is specific to a particular transition of a specific atom. The width of the lineshape indicates the amount of broadening of the transition, due to the effects of both collisions with other particles in the gas and Doppler shift due to the movement of the atom. Since the Doppler shift is proportional to velocity, the width of the transition can be used to estimate the degree of random molecular motion in the gas, expressed macroscopically as temperature. A Doppler shift to the frequencies in the transition can also occur through the bulk motion of the gas, and this can be used to examine the velocity field of the gas. The astronomy community was the first to recognize the utility of these concepts in practical applications, stemming to the early 1930s.1,2 In 1934 Stuve and Elvey3 showed that by including a bulk gas velocity Doppler broadening term in the Voigt equation for the transition lineshape in addition to the random thermal motion term, it was possible to estimate whether a stellar atmosphere was ‘turbulent’ or not based upon the fit of the Voigt equation to the measured transition lineshapes for that atmosphere. Taking the theory a step further, using estimated optical paths or length scales for the stellar atmospheres that they were measuring, they were able to estimate median gas velocities and correlate increasing velocity magnitude with increasing temperature of the stellar atmosphere. More recently, continuously tunable diode lasers have been applied to lineshape measurement of transitions within species in the chemical oxygen-iodine laser (COIL) flowfield as a means to determine number density and laser gain on the I 2P1/2→2P3/2 transition. Davis and Allen et al4,5,6,7 applied lineshape measurement and Voigt fitting methods to various COIL species as a mechanism to determine concentration and translational temperature in the COIL flowfield as an experiment diagnostic. While the effect of the bulk gas velocity was not taken into account in these investigations, the diagnostics developed by these investigations provided the means to do so. Nikolaev et al,8 applied the same type of continuously tunable diode laser to the I 2P1/2→2P3/2 transition to investigate the influence of mean gas velocity through a COIL device upon the laser gain. They showed that by varying the angle at which the diode laser beam passes through the COIL flowfield, the line center gain can be varied through bulk velocity induced Doppler broadening. Using this mechanism, they were able to determine the mean flow velocity for the COIL and convert the laser gain

A heuristic methodology is described that was developed to evaluate the chemical efficiency of high-power chemical oxygen iodine laser (COIL) devices and its application to the specific evaluation of the U.S. Air Force Phillips Laboratory's RotoCOIL laser. A heuristic equation that forms the basis of this methodology and describes the COIL energy flow, energy losses, and power extraction using measured data, code results, and empirical relations is presented. Using this equation and bounding values for some of its terms, it is shown that for the RotoCOIL performance data the experimentally measured average O 2 ( 1 Δ) yield of 0.40 is nearly 38% below that which would be consistent with the measured extraction power. By relating terms of the heuristic equation to performance of individual components of the COIL system, it is concluded that nearly 50% of the efficiency loss for the RotoCOIL laser derives from oxygen generator and delivery losses, whereas 15% is from nozzle inefficiencies and 11% from resonator losses.

: Solid-state lasers convert electrical energy into light using optical excitation. Although efficient, scientists continue research into scaling these devices for high-power applications. Chemical lasers efficiently convert energy derived from chemical bonds and reactions into laser photons. Scientists use chemical lasers for applications that require high-power, lightweight, and self-contained sources of laser radiation because of their inherent high efficiency and scalability. The two classes of chemical lasers are the hydrogen fluoride (HF) laser and the chemical oxygen-iodine laser (COIL).

The US Air Force Research Laboratory has actively pursued the development of the Chemical Oxygen-Iodine Laser (COIL) since its invention in 19771. The power scaling potential of the COIL was verified in the late 1980's on the RotoCOlL device, which was later decommissioned. A smaller COIL teststand (ReCOIL) was then upgraded with a rotating-disk oxygen generator and a variable-height slit nozzle to become the principal testbed for continued COIL development. The modified device was named the Research assessment evice Iodine chemical Laser (RADICL). RADICL has supported several major test campaigns during the past 9 years, many of which have been published. These include 2-D gain maps2, iodine dissociation studies3, magnetic gainswitching demonstrations4, mode-locking5, metal cutting/fiber delivery demonstrations, and more recently measurements of water concentration and oxygen yield . Areview of the major results of these test programs and previously unpublished data are presented.