Optimization and limiting characteristics of CO2 lasers

It is shown that the limiting characteristics of CO₂ lasers are determined mainly by two parameters: the specific power of the electric discharge, referred to the square of the active medium pressure, and the product of the pumping time and the gas pressure. An investigation is made of the dependence of the efficiency and the radiation pulse shape over a wide range of the parameters. For the first time it is noted that the energy from the lower laser level can be given to the upper vibrational states of the symmetric and deformed modes, which allows high radiation density, ～0.2 J/cm³ · atm, to be achieved, as is shown by calculation. Because of energy redistribution in the asymmetric mode the limiting gain coefficient in C₀₂ lasers is ～0.12 cm^?1.     

A study into CO2 laser cutting process

Heat and Mass Transfer - ?To improve the laser cutting process, the modeling of the heating mechanism is essential. In the present study a mathematical modeling of CO2 laser cutting process...     

Energy conditions of gas laser cutting of thick steel sheets

Results of experimental determination of the energy balance in oxygen laser cutting of sheets 5–16 mm thick by a CO ₂ laser in the operation regime of high-quality cutting with the minimum possible degree of surface roughness are presented. Oxygen is used as an assisting gas. For sheets 5, 10, and 16 mm thick, the energy power fluxes, which are involved into the energy balance equation, normalized to the unit thickness of the sheet are found to be independent of the latter and to have close values.     

Specific features of laser cutting of steel sheets and monitoring of sample quality after laser influence

An automated laser system with an 8-kW quantum generator with the beam quality not worse than that of a single-mode laser is described. The possibility of using such a system in procurement production for cutting carbon and stainless steel sheets is demonstrated. The quality control of the blank material shows that the properties of the latter satisfy appropriate standards. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 4, pp. 176–184, July–August, 2006.     

Limiting energy characteristics of pulsed tea co2 lasers

The article presents the results of experimental studies on the determination of the characteristics of the process of absorption of large specific electrical energy densities in a wide range of pressures (0.1–0.5 atm CO₂?2N₂?0.5H₂). The presence of limitations (E₀/p ≥45 V/cm · torr, Q/p=? 1 J/cm³ · atm) which are responsible for the region of existence of a diffusional discharge was established, which made it possible to determine the relationship between the limiting electrical energy density which can be absorbed in the discharge, the initial parameters of the system, and the amount of radiated energy.     

Stable transmission characteristics of double-hump solitons for the coupled Manakov equations in fiber lasers

Nonlinear Dynamics - The prime concern of this study is to simulate the joint effect for the presence of two fractional derivative parameters (memory indices) by providing a novel analytical...     

Thermohydrodynamics of continuous-wave CO2 lasers with a closed cycle of the flow

The problem of pressure losses upon gas motion along a closed circuit containing channels in which heat is supplied to and removed from the gas is studied. The object where the pressure losses are studied is a CO₂ laser with a crossflow. Institute of Theoretical and Applied Mechanics, Siberian Division, Russian Academy of Sciences, 630090 Novosibirsk. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 1, pp. 3–13, January–February, 2000.     

Optimization of the parameters of a CO2 gasdynamic laser

In order to maximize the gain coefficient of a CO₂-N₂-He gasdynamic laser, a total optimization of the stagnation parameters, the concentration coefficient, and the parameters which determine the shape of the nozzle (assuming a quasi-one-dimensional flow model) was carried out. The dependence of the optimized parameters on the limitations imposed by the stagnation temperature of the flow and the critical cross section have been determined.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 3–8, September–October, 1974.     

Population inversion and radiation density in a Q-switched CO2 laser

The mechanism of lasing in a steady-state CO₂ laser has been investigated in [1–3]. In this paper we present a numerical analysis of the processes which occur in a CO₂ laser when the resonator is rapidly Q-switched. It is shown that the transition of the laser into the state with a new Q has an oscillatory form.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 6, pp. 18–23, November–December, 1972.We wish to thank R. I. Soloukhin for his interest and help.     

激光器光谱线宽对布里渊光纤谐振腔谐振特性的影响

针对激光器光谱线宽不可能严格为零的问题,在激光相干理论的基础上,采用光波场叠加的方法计算了布里渊光纤谐振腔的循环光强,详细分析了激光器光谱线宽对布里渊光纤谐振腔谐振谱线宽度和精细度的影响,并进一步分析了光谱线宽对谐振腔受激布里渊散射阈值的影响,最后,引入了线宽压缩的概念分析了布里渊光纤陀螺的灵敏度。分析表明,除了耦合器插入损耗外,激光器光谱线宽也是影响精细度的重要因素,具体影响程度与激光器光谱线宽及谐振腔本征谱线宽度间的相对大小有关,受激布里渊散射阈值随激光器线宽的增加而近似线性增加,另外在其他参数相同的情况下,布里渊光纤陀螺的灵敏度比谐振式光纤陀螺高大约三个数量级。本文为布里渊光纤陀螺的光源选择及光路参数的优化设计过程提供了理论依据。     

Effect of flow conditions on the amplification and generation of pulsed gasdynamic lasers in N2O and CO2

The weak signal amplification is studied in jets involving N₂O-N₂He, N₂O-N₂ and CO₂-CO-N₂-He mixtures with installations combining a shock-tube and slit-throat (1.5×40 and 2.5×70 mm²) or two-dimensional wedge (=15°, A/A _* = 15) nozzles. The relationships between amplification and gasdynamic characteristics are elucidated.     

Effect of laser radiation on the vibrational distribution of CO2

In connection with progress in the field of CO₂ lasers, questions of the vibrational kinetics of molecules of CO₂ have been discussed in many communications. In a majority of cases of practical importance, the distribution of CO₂ is due to processes of vibrational exchange (V-V) on which is based the well-known thermodynamic model [1]. In other cases, the V-V exchange does not determine the vibrational distribution, since the perturbation is small; therefore, it is found sufficient to consider a small number of levels of CO₂ (usually three), whose populations satisfy the linear equations of the balance [2]. There is the possibility of conditions where the vibrations are strongly excited and, at the same time, V-V processes are insignificant (a very small CO₂ impurity in the inert gas, with a high degree of ionization). Then the number of equations becomes large. The present article discusses one such case: the excitation of a steady-state vibrational distribution in a glow discharge by laser radiation, whose solution is rather graphic.     

Choice of turbulence model for calculating gas dynamic CO2 lasers with selective thermal excitation

Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 163–168, Septebmar–October, 1990.