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Chemical Oxygen Iodine Laser (COIL) is the shortest wavelength (1.315 μm) chemical laser employing singlet oxygen molecules as the pumping species and iodine atoms as lasing species. Singlet Oxygen Generator (SOG) is essentially the heart of this laser device which is basically a gas–liquid phase chemical reactor. SOG facilitates the reaction between a basic hydrogen peroxide solution (BHP, H2O2 + KOH) and chlorine gas to produce singlet oxygen molecules. Centrifugal Bubble Single Oxygen Generator (CBSOG) is a potential candidate for an alternative SOG with better operating conditions for high throughput and high power COIL systems. In CBSOG Chlorine gas is bubbled through a layer of BHP solution and the required reaction takes place at the gas–liquid interface of the formed bubbles under high speed rotation of the chamber for gravity independent operation. The performance of this device largely depends on the bubble formation characteristics and their traverse inside the BHP layer. The aim of this paper is to present the numerical analysis of the mechanics of bubble formation, detachment and movement in the BHP layer for different operating parameters as applicable to COIL. The determination of conditions for the transition from bubbling to the jetting regime at different centrifugal accelerations of high magnitude (G ∼ 204 g, 306 g & 387 g) with low liquid column thickness (∼6–8 mm) operating under low pressure (∼100 torr) is another point of focus. The Volume of Fluid (VOF) method has been used for the 3-D transient interface tracking between the phases. This paper also compares the simulation results for various gas flow rates and centrifugal accelerations with select experimental results reported elsewhere showing reasonably good agreement.

Present paper focuses upon development of thermal stabilization scheme based on pulse width modulation (PWM) controller used for iodine evaporation in flowing chemical laser. Iodine acts a lasing medium in chemical oxygen iodine laser (COIL). In COIL, iodine crystals are put in iodine chambers and needs to be continuously evaporated in order to get vapor iodine. For efficient COIL operation, stabilized iodine evaporation is one of the prime needs. In addition, iodine transportation lines are also required to be heated to ~ 75°C-85°C in order to restrict the iodine deposition during transport. Iodine being hazardous to human beings, the said thermal operation has to be continuously monitored and controlled to provide uniform flow of iodine during safe laser operation. Thermal actions are performed by using several rod heaters and belt heaters. A PWM controller based in house thermal stabilization scheme has been developed using feedback mechanism for iodine evaporation with an accuracy of ±0.5°C instead of using commercially available controllers. It comprises of Operational Amplifier LF 356, Instrumentation Amplifier (IA) AD 620, LM 339 Comparator ICs, K type thermocouple and solid state relay (SSR).The developed hardware has been interfaced with data acquisition system (DAS) and all the temperatures were monitored and recorded online.

In the last century the laser was invented in 1961 after that scientists aspired to produce a high-power laser (HPL) to be used in many fields as communications in a far-field, and for industrial purposes such as carving, cutting, and leveling, and in military applications, a super-powerful laser is used to destroy different enemy targets After several attempts and painstaking experiments, more than one conception was reached to reach a high-power laser, the first of which is the chemical laser, for example, the carbon dioxide laser, the carbon monoxide laser, the hydrogen and fluorine laser, the second type free-electron laser, and finally fiber laser. in this paper a chamber test of a high-power fiber laser beam (CTHPF) measures the absorption and scattering of the laser beam in a case almost real in the far-field, it simulates atmospheric aerosol and the effect of the laser beam after chamber on the piece of solid material like stainless steel and aluminum to measure heat capacities (HC) with a versus temperature (T), which its Produced by the laser beam.

A DF chemical laser can transfer chemical energy into high-power laser beam in the megawatt range, which may be used for industrial manufacturing or military purposes. Reacting flowfield and optical field always interact in the process of optical energy extraction from the chemical laser cavity. On the one hand, nonuniform distribution of gain medium may affect the transmission of light beams, may lead to light deflection and phase deviation furtherly. On the other, power extraction may cause the variation of species and energy distribution in the flowfield. Therefore a numerical simulation is presented for investigating the interaction of chemical reaction flowfield and optical field. An 11-species (including DF molecules in various excited states of energies), 23-step chemistry model is adopted for the chemical reaction of the DF chemical laser system. Meanwhile, laser oscillating in the optical cavity is solved by geometric optical models. Variations of flow and optical fields from the establishment to the stabilization status in the optical cavity are simulated. Major results reveal that stimulated radiation has dominant effects only on the concentrations of the lasing species (DF excited molecules), and it has relatively minor influence on the basic fluid dynamic variables. For the case without lasing, the complete population inversion phenomena could be found in wider range, which does not occur for lasing. The lasing output is based on the partial population inversion of the vibration-rotation transition in DF molecules.

The rate constants for H2 -HF energy transfer processes, especially for those in vibrationally excited states, are very demanding in astrophysics and chemical laser engineering, especially for those in vibrationally excited states. Based on our recent potential energy surface, we used the coupled-states approximation including the nearest neighboring Coriolis couplings with energy-based local basis set to perform dynamics calculation for the H2 -HF energy transfer system. Rate constants for vibrational transitions (1; 3) → (0; 4), (1; 3) → (2; 2), and (0; 3) → (1; 2) were obtained. For state-to-state rate constants, transitions that have no internal angular momentum gap dominate at high temperatures. The vibrational-resolved rate constant for (1; 3) → (0; 4) initially decreases and then increases with the temperature, while those for (1; 3) → (2; 2), and (0; 3) → (1; 2) transitions monotonically increase. The calculated rate constants are in good agreement with the available experimental results. These dynamical data can be further applied to the numerical simulation of hydrogen fluoride chemical laser. © 2018 Wiley Periodicals, Inc.

The chemical kinetics of supersonic hydrogen fluoride (HF) chemical lasers determines combustion characteristics and output power. However, the inherent complexity of chemical reactions and complex structure still challenge the numerical simulations involving a comprehensive chemical mechanism. Therefore, a high fidelity and low computational consuming model is important for design purpose. This paper presents a strategy to generate a reduced mechanism for HF chemical lasers. Based on a detailed HF chemical mechanism consisting of 16 species and 153 elementary reactions, a specific skeletal mechanism including 11 species and 58 elementary reactions is generated. Finally, we obtain a further reduction mechanism including 11 species and 39 elementary reactions by combining sensitivity analysis and rate of production analysis. The computational cost for simulation of supersonic HF chemical lasers with the reduced mechanism is less than that with the detailed model. The principal contribution of the work is to provide a low computational consuming model.

Al is doped into 4H-SiC by irradiating pulsed KrF excimer laser to 4H-SiC immersed in AlCl3 aqueous solution. Impact on doping depth of the use of expanded laser-pulse width is investigated. Expanded laser pulse is produced by splitting and recombining the laser beam with mirrors. The laser pulse width was expanded from its original width of 55–100 ns, while the peak power of the expanded pulse is as half as that of the original pulse under the same laser fluence. Multiple shots of the expanded laser pulses increased the doping depth at the Al concentration of 1×1016 /cm3 to 100 nm from 30 nm of the single shot of the original short, high-peak power laser. The increased doping depth could be due to enhanced diffusion by extra vacancies generated by the repeated laser irradiations. Due to the smaller laser peak power, the expanded pulse laser can suppress damage generation under multiple laser shots and, as a result, leakage current of the pn junction diode is kept low.

An experimental study of combustion-driven HBr chemical laser based on D2/NF3 combustion was carried out. The exotherm of the reaction system was analyzed, and the thermal blockage issue of supersonic flow was solved by adjusting the buffer coefficient ω. By optimizing the laser operating conditions, a maximum HBr laser output of 141W was obtained, with the primary laser lines being HBr P1(5) , P1(6) , and P3(6).

A chemical flow reactor is used to study the vibrational population distribution of CO produced by a reaction between carbon vapor generated in an arc discharge and molecular oxygen. The results demonstrate formation of highly vibrationally excited CO, up to vibrational level v = 14, at low temperatures, T = 400–450 K, with population inversion at v = 4–7, in a collision-dominated environment, 15–20 Torr. The average vibrational energy per CO molecule formed by the reaction is 0.6–1.2 eV/molecule, which corresponds to 10–20% of reaction enthalpy. The results show feasibility of development of a new CO chemical laser using carbon vapor and oxygen as reactants.

In this paper, we report on the characterization of Si thin films doped by wet-chemical laser processing. Using this method, implantation and dopant activation can be performed simultaneously. After laser doping, the mobility, carrier concentration, and resistivity of the films were 74 cm2/V·s, 5.5 × 1017 cm−3, and 0.15 Ω·cm, respectively.

Deuterium compounds were initially used in the military and energy fields, primarily in nuclear weapons, nuclear energy industry, deuterium fluoride-based chemical laser weapons, and so on. Indeed, nuclear fusion research has led to the development of high-power lasers, high-power microwaves, intense beam technology, and cryogenic superconductivity. Later, as a special functional material, deuterated compounds are stable in nature without radioactivity, which play an important role and become more and more widely used in the fields of civil materials, agriculture, fishery, biomedical research, pharmaceutical research, chemical theory research, earth science, analytical testing, new material research and development.

New designs of a defense system using a chemical oxygen iodine laser (COIL) are presented to realize a boost-phase interception of a ballistic missile. Although a space-based laser (SBL), in which the Hydrogen-Fluoride chemical laser is the primary candidate, can realize such a defense system, many SBLs are necessary to cover even a single missile site because they need to continuously go around the earth. This is an expensive system if the potential enemy is a small country. Meanwhile a high energy laser (HEL) carried by a high-altitude airship (HAA) can realize a geostationary defense system if the HEL is quite lightweight. A chemical oxygen-iodine laser (COIL) is suitable since it does not require a heavy electric power supply. But since the COIL should be as light as possible, it would be more advantageous if it can operate without a vacuum pump that requires a large electric-power supply and cooling water. Rate-equation based simulations have been performed to see if it can operate without a vacuum pump by filling a buffer gas at the pressure higher than the outside. The simulation results indicate that it can operate continuously at an altitude of 20 km where the atmospheric pressure becomes ~5,400 Pa (~40 Torr). Moreover, since atmospheric turbulence is greatly reduced at that altitude, adaptive optics is also not necessary for focusing the beam after a long propagation. A simple focusing mirror can focus the beam tightly enough to destroy the target of >100 km away.

Infrared gas lasers find application in numerous civil and military areas. Such lasers are therefore being developed at different institutions around the world. However, the development of chemical infrared gas lasers such as chemical oxygen iodine lasers (COIL) involves the use of several hazardous chemicals. In order to exploit full potential of these lasers, one must take diligent care of the safety issues associated with the handling of these chemicals and the involved processes. The present paper discusses the safety aspects to be taken into account in the development of these infrared gas lasers including various detection sensors working in conjunction with a customized data acquisition system loaded with safety interlocks for safe operation. The developed safety schemes may also be implemented for CO2 gas dynamic laser (GDL) and hydrogen fluoride–deuterium fluoride (HF–DF) Laser.

The 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.