Oxygen-iodine Laser Research Articles

A Chemosorption Vacuum Pump for a Chemical Oxygen Iodine Laser with CO2 Buffer Gases

We present the design and investigation of a novel chemosorption vacuum pump (CSVP) for discharging the exhaust gases of a chemical oxygen-iodine laser system diluted with carbon dioxide (CO2-COIL). The CSVP comprises two fixed-bed reactors separately filled with CO2/H2O and O2/I2/Cl2 adsorbents, which can efficiently chemically absorb the CO2-COIL exhaust gases at room or higher temperature. We consider the effects of the adsorbents in different specifications and fixed beds of various constructions on the adsorption performance of the CSVP. We develop and study the sealed CO2-COIL system with the CSVP. We achieve a stable operation with a cumulative duration time of 40 s for four runs and an average output power up to 2.0 kW at a Cl2 flow rate of ∼158 mmol/s and a CO2 flow rate of 132 mmol/s. The experimental results indicate that the COIL system with the CSVP performs similarly to a conventional COIL with a vacuum tank. Taking into account that the CSVP is free of vibration and noise, avoids air pollution, is easily operated, and has a short preparation time, we believe that the chemosorption vacuum pump is an excellent alternative pump system for a transportable COIL system.

Forecast of intense near- and mid-IR laser radiation propagation along slant atmospheric paths

The effectiveness of the use of intense radiation from different near- and mid-IR laser sources propagating along high-altitude slant optical paths is numerically estimated on the basis of the optical model of the Earth’s atmosphere developed by the authors. Different laser sources, including chemical oxygeniodine laser (COIL), chain chemical DF laser, and carbon-monoxide (CO) laser are considered with different optical weather conditions taking into account linear and nonlinear optical effects. A COIL source is shown to be the most preferable in terms of the total laser power transmitted along a path, because of weak atmospheric attenuation and minimal effects of nonlinear factors. In addition, this laser source shows the best performance in terms of the mean radiation intensity at a receiver. Among chemical multiwavelength lasers, DF lasers lead in terms of the power transfer function.

氧碘化学激光器腔镜表面缺陷的观察与分析

氧碘化学激光器腔镜表面缺陷的观察与分析

Experimental investigation and numerical simulation on continuous wave laser ablation of multilayer carbon fiber composite

Laser beam machining is one of the most widely used advanced processing techniques, which can be applied to compound materials. As a large number of photons are absorbed into the composite, the subsequent local heat storage, charring and potential delamination make the study for the effect of laser on complex materials become significant. In this paper, a carbon fiber epoxy composite laminated sheet is irradiated by continuous wave chemical oxygen iodine laser. The peak temperature of front surface, the temperature distribution of rear surface, and the appearance of ablation zone are presented. Further, based on the birth–death elements technique of finite element method, a three-dimensional model for simulating the transient temperature distribution and material removal has been developed under the same condition. The results reveal that the peak temperature of irradiated region ranges from 2800 K to 3100 K, and the center point shows a higher temperature rise rate than the surroundings in the irradiated zone. The measured data and predicted data are in a good consistency, which suggests that the numerical model is appropriate for simulating laser ablation of carbon fiber epoxy composites.

Overview of Optical Techniques for Characterization of High-Power Infrared Gas Lasers

High-power lasers typically form a multidisciplinary technological area laced with innumerable challenges in its realization as a practical system. The prime amongst them are infrared gas laser sources, such as carbon dioxide gas dynamic laser, hydrogen fluoride, deuterium fluoride laser, and chemical oxygen iodine laser. Each of these laser systems is associated with a unique as well as complex active medium environment involving intense interaction between lasing and pumping species under specific gas dynamic conditions. The parameters viz., specie concentration of the lasing, pumping mediums and other by-products, medium homogeneity, individual constituent gas flow rate, pressure and temperature at critical locations, and cavity Mach number are very crucial in determining the output of the gas laser system. It is essential to determine these parameters nonintrusively, with necessary precision so as to optimize these lasers especially in case of large-scale systems. Thus, the focus of this paper is to review and discuss the existing applicable optical detection methodologies ranging from the more established methods, such as optical absorption/emission spectroscopy, to very contemporary, such as Raman spectroscopy, cavity ring down spectroscopy, laser-induced fluorescence/planer laser-induced fluorescence, and so on, which are relevant for the diagnostic needs of gas lasers.

Optically (solar) pumped oxygen-iodine lasers

We present the results of theoretical and experimental studies demonstrating the possibility of developing an oxygen-iodine laser (OIL) with direct optical pumping of molecular oxygen involving inter-molecular interaction with charge transfer from donor molecule (buffer gas) to acceptor molecule (oxygen). This interaction lifts degeneracy of the lower energy states of molecular oxygen and increases its absorption cross section in the visible spectral region and the UV Herzberg band, where high quantum yield of singlet oxygen is achieved (QY ∼ 1 and QY ∼ 2, respectively) at the same time. A pulse-periodic optical pump sources with pulse energy of ∼50 kJ, pulse duration of ∼25 μs, and repetition rate of ∼10 Hz, which are synchronized with the mechanism of singlet oxygen generation, are developed. This allows implementation of a pulse-periodic oxygen-iodine laser with an efficiency of ∼25%, optical efficiency of ∼40%, and parameter L/T ∼ 1/1.5, where T is the thermal energy released in the laser active medium upon generation of energy L. It is demonstrated that, under direct solar pumping of molecular oxygen, the efficiency parameter of the OIL can reach L/T ∼ 1/0.8 in a wide range of scaling factors.

An experimental research on the mixing process of supersonic oxygen–iodine parallel streams

The O 2 ( 1 Δ)/I 2 mixing process is one of the most important steps in chemical oxygen–iodine laser (COIL). Based on the chemical fluorescence method (CFM), a diagnostic system was set up to image electronically excited fluorescent I 2 (B 3 П 0 ) by means of a high speed camera. An optimized data analysis approach was proposed to analyze the mixing process of supersonic oxygen–iodine parallel streams, employing a set of qualitative and quantitative parameters and a proper percentage boundary threshold of the fluorescence zone. A slit nozzle bank with supersonic parallel streams and a trip tab set for enhancing the mixing process were designed and fabricated. With the diagnostic system and the data analysis approach, the performance of the trip tab set was examined and is demonstrated in this work. With the mixing enhancement, the fluorescence zone area was enlarged 3.75 times. We have studied the mixing process under different flow conditions and demonstrated the mixing properties with different iodine buffer gases, including N 2 , Ar, He and CO 2 . It was found that, among the four tested gases, Ar had the best penetration ability, whilst He showed the best free diffusion ability, and both of them could be well used as the buffer gas in our experiments. These experimental results can be useful for designing and optimizing COIL systems. • An analysis method of O 2 ( 1 Δ)/I 2 mixing process using CFM was proposed. • A trip tab set was demonstrated to enhance O 2 ( 1 Δ)/I 2 mixing efficiently. • The optimal flow conditions for mixing with different buffer gases were given. • A comparison between different gases used as iodine buffer gas was conducted.

Adsorption of iodine from COIL waste gas on soaked coal-based activated carbon

The chemical oxygen–iodine laser (COIL) has wide application prospects in military, industrial and medical treatment fields as a second generation gas chemical laser to follow the first HF/DF chemical laser. However, a COIL releases large amounts of gas, such as helium, oxygen, chlorine and iodine. Chlorides have a serious corrosive effect on the system, especially iodine vapor crystallization, which seriously endangers the normal use of vacuum systems, and radioactive methyl iodide, which is hazardous to operators and pollutes the environment. The use of soaked coal-based activated carbon as an adsorbent for removing methyl iodine is proposed, while it is proposed that coal-based activated carbon is an effective adsorbent for removing stable iodine. The research conducted in this work shows that iodine residues are less than 0.5 μg ml−1 after the adsorption treatment and the decontamination factor of the coal-based activated carbon for removing stable iodine is more than 1000. Using this method can achieve the purpose of removing harmful iodine, satisfy the requirements for engineering applications, and also be applied to other nuclear power plant flue gas treatments.

ChemInform Abstract: Overview of Iodine Generation for Oxygen—Iodine Lasers

AbstractReview: 47 refs.

氧碘化学激光器故障诊断技术

氧碘化学激光器故障诊断技术

高能化学氧碘激光激光近场高频光角谱特性研究

高能化学氧碘激光激光近场高频光角谱特性研究

光腔与扩压器的一体化优化数值模拟

The performance of supersonic diffuser downstream the cavity in chemical oxygen-iodine laser pressure recovery system can obviously influence the flow field quality in cavity, and its static pressure recover and total pressure loose performance can determine the pressure recovery system size downstream the diffuser. This paper uses the numerical simulation method to research the influence of supersonic diffuser design parameter such as diffuser angle and diffuser outline and back pressure and so on. The study shows that, the static pressure ratio was increased about 33% and the total pressure recover coefficient was increased to 0.484 by means of adding a constant section with wedges between the cavity and the supersonic diffuser. At the same time, the flow filed quality such as static pressure and Mach number distribution in cavity was obviously improved.

翼片扰动对COIL超音速平行流混合的影响

The process of oxygen-iodine mixing is one of the most important steps in chemical oxygen-iodine laser (COIL). The quality of oxygen-iodine mixing is directly related to the COILs operating efficiency and beam quality. Employing chemical fluorescence method (CFM)，the effects of trip tabs on the process of supersonic mixing of parallel oxygen-iodine flows in COIL was studied. The experimental results indicated that the mixing process with 1# trip tabs was improved obviously. Comparing with the mixing without trips, when using 1# trip tabs, the streamwise distance required by the fluorescence to reach the centerline of the primary flow was shortened largely and the area ratio of fluorescence in the region of iodine dissociation region was enlarged by 4.2 times. When using 2# trip tabs, the streamuise distance decreased further by 40%-60%, and the area ratio value increased by 20%-40% again. Using 2# trip tabs, the mixing processes with and without the primary buffer gas were compared, and the results showed that the latter was better.

非稳腔氧碘激光器近场杂散光传输特性

非稳腔氧碘激光器近场杂散光传输特性

Analysis of CW Oxygen-Iodine Laser Performance Using Similarity Criteria

A simplified single-frequency two-level model for predicting power extraction from a CW oxygen-iodine laser (OIL) considering relaxation losses has been developed. The model predicts that the energy efficiency of CW OILs with stable resonators depends on three similarity criteria. Criterion γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> is the ratio of the residence time of active medium in the resonator to the singlet oxygen O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ( <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> \triangle) energy extraction time at an infinite intraresonator intensity. Criterion Π is small-signal gain to the threshold ratio. Criterion Λ is the relaxation to excitation rate ratio for the electronically excited iodine atoms I( <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sub> ). The analysis of the calculated and experimental data show that effective power extraction from the CW OIL active medium is achieved when the values of the similarity criteria are in the ranges: γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> =4-6, Π = 3-8, and Λ ≤ 0.01.

A pared-down gas-phase kinetics for the chemical oxygen-iodine laser medium

Kinetic data obtained in the last decade has resulted in revisions of some mechanisms of excitation and deactivation of excited states in the chemical oxygen-iodine laser (COIL) medium. This review considers new kinetic data and presents analyses of the mechanisms of pumping and quenching of electronically and vibrationally excited states in the oxygen-iodine laser media. An effective three-level model of I2 molecule excitation and relaxation has been developed. The calculated effective rate constants for deactivation of I2(X,11⩽υ⩽24) by O2, N2, He and CO2 are presented. A simplified kinetic package for the COIL active medium is recommended. This model consists of a 30-reaction set with 14 species. The results of calculations utilizing simplified model are in good agreement with the experimental data.

Experiment and Simulation on a New Swirl-Jet-Type Singlet Oxygen Generator

the singlet oxygen generator (sog) is the heart of chemical oxygen iodine laser. a new swirl-jet-type sog was proposed which consists of a reaction part and a separation part. planar laser-induced fluorescence combined with maximum entropy method were used to study the droplet size distribution, and a modified muschelknautz model and computational fluid dynamics were used to simulate the separation efficiency of vapor and liquid phases. the results of the net reaction predict 99.2% conversion of chlorine and 42.2% yield of singlet oxygen, demonstrating the superiority of the new type of sog.

Kinetics of energy deactivation in the O2(1Δ)-I medium

The kinetics of energy-exchange and quenching processes in the O2(1Δ)-I medium plays an important role in the operation of the chemical oxygen-iodine laser. However, up to now, many of the key processes in this medium are not fully understood. In this work, the flow tube technique is used to determine the rate of excitation energy deactivation in the O2(1Δ)-I medium in the presence of small concentrations of water and carbon dioxide. The concentrations of electronically excited species are measured with spectrometers calibrated in absolute spectral responsivity. The effective rate constant for the deactivation of O2(1Δ) molecules in processes involving iodine atoms is determined. The results are compared to those obtained in previous works.

Numerical study of He/CF3I pulsed discharge used to produce iodine atom in chemical oxygen-iodine laser

The pulsed discharge for producing iodine atoms from the alkyl and perfluoroalky iodides (CH3I, CF3I, etc.) is the most efficient method for achieving the pulse operating mode of a chemical oxygen-iodine laser. In this paper, a one-dimensional fluid model is developed to study the characteristics of pulsed discharge in CF3I-He mixture. By solving continuity equation, momentum equation, Poisson equation, Boltzmann equation, and an electric circuit equation, the temporal evolution of discharge current density and various discharge products, especially the atomic iodine, are investigated. The dependence of iodine atom density on discharge parameters is also studied. The results show that iodine atom density increases with the pulsed width and pulsed voltage amplitude. The mixture ratio of CF3I and helium plays a more significant role in iodine atom production. For a constant voltage amplitude, there exists an optimal mixture ratio under which the maximum iodine atom concentration is achieved. The bigger the applied voltage amplitude is, the higher partial pressure of CF3I is needed to obtain the maximum iodine atom concentration.

The proposal and realization on more exact modeling of COIL performance

AbstractThe chemical oxygen–iodine laser (COIL) is the shortest-wavelength high-power chemical laser that has been demonstrated. The characteristics, such as good atmospheric propagation, short wavelength and excellent transmission through optical fibers, make the COIL a good candidate for high-power laser application. To model the complete COIL lasing interaction, a three-dimensional formulation of the fluid dynamics, species continuity and radiation transport equations is necessary. The computational effort to calculate the flow field over the entire nozzle bank with a grid fine enough to resolve the injection holes is so large as to preclude doing the calculation. The approach to modeling chemical lasers then has been to reduce the complexity of the model to correspond to the available computational capability, adding details as computing power increased. The modeling of lasing in the COIL medium is proposed, which is coupling with the effects induced by transverse injection of secondary gases, non-equilibrium chemical reactions, nozzle tail flow and boundary layer. The coupled steady solutions of the fluid dynamics and optics in a COIL complex three-dimensional cavity flow field are obtained following the proposal. The modeling results show that these effects have some influence on the lasing properties. A feasible methodology and a theoretical tool are offered to predict the beam quality for large-scale COIL devices.