优化封离型CO2激光工作气体的动力学机理研究

详细讨论了封离型CO2激光器中CO2,N2和He三混合气体含量被优化组合后的激光动力学机理.气体优化可以提高激光输出功率的主要机理是通过适当增加N2含量,使N2激发态与CO2激光上能级的碰撞频率增加,提高了激光能级粒子数密度和相对布居数.同时,适当减少CO2含量,使总的电子动量输运碰撞频率减小、放电电流增大,导致增加激光上转动能级的弛豫速率和减小能级寿命,从而提高了谐振腔内的激光饱和光强.     

管板式大功率横流CO2激光横模测量及数值模拟

为了提高激光稳定性和激光加工质量,实验测量了大功率横流CO2激光横模,并理论分析了横模形成机理。针对大功率横流CO2激光器管板式电极结构,由麦克斯韦方程给出电场的横向分布,并通过数值计算得到了激光强度的横向分布。实验结果与数值模拟得到的激光能量分布基本一致。结果表明,在给定放电电压条件下,电极结构和气体流动速率决定了激光横模峰值大小,激光峰值的横向位置取决于气体流动的速率。     

管板式大功率横流CO2激光横模测量及数值模拟

为了提高激光稳定性和激光加工质量,实验测量了大功率横流CO2激光横模,并理论分析了横模形成机理。针对大功率横流CO2激光器管板式电极结构,由麦克斯韦方程给出电场的横向分布,并通过数值计算得到了激光强度的横向分布。实验结果与数值模拟得到的激光能量分布基本一致。结果表明,在给定放电电压条件下,电极结构和气体流动速率决定了激光横模峰值大小,激光峰值的横向位置取决于气体流动的速率。     

CO2激光器五种混合气体压强优化

应用遗传算法,以输出激光功率为目标函数,优化确定了普通CO2激光器五种工作气体（CO2, N2, He, Xe, H2）的最佳充气量。对1.2m长谐振腔,在15kV放电条件下,优化的充气量分别为pCO2=1.15×133.3Pa, pN2=7.32×133.3Pa, pHe=12.95×133.3Pa, pXe=0.36×133.3Pa和pH2=0.01×133.3Pa。优化后激光功率比未优化前可提高1.27倍。     

脉冲CO2激光器的多频动力学模型

建立了适用于各种气压下(20×133—20×10⁵ Pa)的脉冲CO₂激光器的六温度多频动力学模型，该模型考虑了增益谱线重叠效应，序列带、热带的影响，以及非洛伦兹线型效应.对模型进行数值求解可以预言和解释不同气压下的脉冲CO₂激光器的输出特性，有助于评价不同的抽运设计和研究可调谐特性，为设计脉冲CO₂激光系统提供理论支持. 关键词： 2激光器')" href="#">CO₂激光器 激光动力学 六温度模型 增益谱线重叠     

优化铜蒸气激光的动力学强化机理研究

研究铜蒸气激光优化后可提高输出功率的激光动力学机理.结果表明,1)优化后储能电容和峰化电容减小,改善了激光头与LC放电电路的匹配,使馈入激光管的功率增加;2)管壁温度适当提高,使铜激光各能级粒子数密度增大;3)电脉冲期间电子温度上升前沿加快,电子密度明显提高 关键词： 铜蒸气激光 动力学强化 优化机理     

光泵气体THz激光器用CO2泵浦源腔内光场模式

CO2泵浦源是光泵气体太赫兹激光器的核心器件之一,其性能直接关系到太赫兹激光器的工作稳定性。CO2泵浦源一般由闪耀光栅作为全反射尾镜,构成特殊的光栅腔实现波长的选支输出。采用传输矩阵的特征向量法对光栅谐振腔的腔内光场模式进行了理论分析与数值模拟,计算了光栅腔的一系列本征模式及相应的衍射损耗。结果表明光栅腔的腔内模式特性等效于一个平凹腔,而对于大菲涅尔数的光栅腔, Littrow波长的附近支线也可能具有衍射损耗较低的低阶模,可能优先于Littrow波长的高阶模起振,导致光栅腔的波长选择性降低。     

光泵气体THz激光器用CO2泵浦源腔内光场模式

CO2泵浦源是光泵气体太赫兹激光器的核心器件之一,其性能直接关系到太赫兹激光器的工作稳定性。CO2泵浦源一般由闪耀光栅作为全反射尾镜,构成特殊的光栅腔实现波长的选支输出。采用传输矩阵的特征向量法对光栅谐振腔的腔内光场模式进行了理论分析与数值模拟,计算了光栅腔的一系列本征模式及相应的衍射损耗。结果表明光栅腔的腔内模式特性等效于一个平凹腔,而对于大菲涅尔数的光栅腔, Littrow波长的附近支线也可能具有衍射损耗较低的低阶模,可能优先于Littrow波长的高阶模起振,导致光栅腔的波长选择性降低。     

V2CO2MXene从CO2/N2混合气体中选择性吸附CO2的第一性原理计算

二氧化碳作为温室气体中最重要的组成部分,其含量的变化将直接影响全球气候变化,在燃烧后气体中选择性捕获CO₂,对减缓因CO₂浓度过高引发的环境问题具有十分重要的意义.本文采用第一性原理计算的方法,研究了V₂CO₂ MXene材料对CO₂的选择性吸附性能.首先研究了不同官能团V₂CT_X MXene材料的结构和性质,发现V₂CO₂具有良好的稳定性.后研究了V₂CO₂对CO₂的吸附行为,结果表明,当CO₂被水平吸附时,V₂CO₂对CO₂气体分子的吸附能力较强且均满足在高性能吸附剂表面吸附CO₂的理想值(-0.42 eV-0.82 eV),可以适用于探测/捕获CO₂气体分子.此外,进一步研究了相同条件下V<...     

CO2激光作用下运动石英玻璃的温度分布

研究了运动石英玻璃板在CO2激光作用下的热效应,在考虑表面辐射和空气对流的情况下建立了数学模型,采用有限元软件ANSYS进行数值计算,得到了运动情况下石英玻璃的温度分布。比较了激光功率、光斑半径和运动速度对温度分布的影响,得到了温度分布与运动速度和激光参数之间的关系。结果显示石英玻璃板的表面温度随激光功率的增加而增加,随光斑半径、运动速度的增加而减小。     

Gas breakdown with nanosecond CO2 laser radiation

The thresholds for CO₂ laser induced breakdown and their variation with pulse width have been measured at various pressures for Ar, N₂ and an 8/1/1 laser mixture of He/CO₂/N₂ using 3–40 ns duration pulses. These measurements indicate that excited state production plays a dominant role in determining the threshold for nanosecond duration pulses. This has been confirmed by the good agreement obtained between the measured and theoretical thresholds.     

CO2 laser cutting of slate

Slate is a natural stone which has the characteristic that shows a well-developed defoliation plane, allowing to easily split it in plates parallel to that plane which are particularly used as tiles for roof building. At present, the manufacturing of slate is mostly manual, being noisy, powdery and unsafe for the worker. Thus, there is a need to introduce new processing methods in order to improve both the working conditions and the quality of the products made of slate.Following the previous work focused on the drilling and cutting of slate tiles using a Nd : YAG laser, we present in this paper the results of the work carried out to explore the possibilities to cut slate plates by using a CO₂ laser. A 1.5 kW CO₂ laser was used to perform different experiments in which, the influence of some processing parameters (average power, assist gas pressure) on the geometry and quality of the cut was studied. The results obtained show that the CO₂ laser is a feasible tool for a successful cutting of slate.     

AC-chopper application for CW CO2 laser

A microprocessor-based algorithm was developed to control the power supply to a CO₂ laser using an AC-chopper method. This system was connected directly to a CO₂ laser tube without the need for a dc-dc converter or the storage capacitance of a multilevel circuit. The typical CO₂ laser power supply system had a full-bridge series resonant inverter or voltage multiplier. AC-to-AC converter schemes using zero voltage switching (ZVS) can be used efficiently and economically for low and medium power applications.This paper reports the performance characteristics of a symmetrical AC-chopper technology that can maintain the quality of the ac output of a CO₂ laser tube, regardless of the amount of switching loss. The laser was operated to an output power, maximum system efficiency total gas mixture of 37.2 W, 92%, and CO₂:N₂:He=1:9:15, respectively. The laser system, AC-chopper power supply and its operation were examined.     

Mathematical modeling of hybrid CO2 laser

A Teller–Landau six-temperature model describing the dynamic emission of single-mode TEA CO₂ laser has been adapted. This model has been also used to describe the mechanism of obtaining relatively high-power output pulses from hybrid TE-TEA or CW-TEA CO₂ laser consisting of high- and low-pressure sections. The suggested mathematical model allows to investigate the mechanism which limits the TEA oscillation to single longitudinal mode (SLM) due to the narrow gain bandwidth of low-pressure section, and also to study the effect of the laser input parameters on the smooth output laser pulse parameters. In addition, numerical solutions of non-linear rate equation system of the suggested model are quantitatively discussed. The solutions describe the radiation field intensity, the population inversion, and the energy transfer processes. The calculated values of maximum peak power, total energy in pulse, pulse width, etc. are in a very good agreement with the observed experimental values.     

Optimization of three gas compositions in a CO2 laser

Three pressures of gases (CO₂, N₂ and He) added into CO₂ laser tube are optimized for obtaining maximal laser output power by applying a genetic algorithm and solving the CO₂ laser kinetics equations. After the optimization, the laser power is increased by 96% as compared with a non-optimal case.     

Intracavity absorption of CO2 laser radiation by chlorofluorocarbon (CFC) gases

Intracavity absorption method was applied to determine the absorption coefficients of trichlorofluorocarbon CCl₃F (CFC-11), dichlorodifluorocarbon CF₂Cl₂ (CFC-12) and chlorodifluorocarbon CHClF₂ (CFC-22) vs. the pressure in the cell inside the cavity of a tunable CO₂ laser at different spectral lines on branches 9R and 10P.The laser output power was measured vs. the gas pressure at different spectral lines on branches 9R, 9P, 10R and 10P of CO₂ molecule transitions. A strong absorption was observed for lines of 9R and 10P branches, whereas a weak absorption was noticed for lines of 9P and 10R branches.The calculation of absorption coefficients was restricted for 9R and 10P due to the oscillating variation of the output power of CO₂ laser vs. the CFC pressure, which was occurred for the lines of 9P and 10R.On the basis of absorption coefficients, the absorption cross-sections for CFC-12 were calculated and compared with the absorption cross-sections found from the previous experiment (where the cell was located outside the cavity), NIST and HITRAN databases, respectively.The obtained data could be useful for CFC gases detection as pollutants in the atmosphere.     

High-power multibeam CO2 laser for industrial applications

Multibeam CO₂ lasers consist of a large number of closely packed parallel glass discharge tubes, all sharing a common plane parallel resonator. This paper describes construction and operation of a CW multibeam CO₂ laser consisting 20 discharge tubes and cooled length of 1500 mm, delivering 1 kW power. A high-frequency pulser is used for producing preionization in all discharge sections for initiating the main DC discharge simultaneously in all discharge tubes. Plane parallel resonator consists of a plane ZnSe mirror of 90 mm diameter having 60% reflectivity and a gold-coated copper mirror of same diameter. This laser operates in waveguide regime and laser power is not critically sensitive to mirror misalignment.     

Optically pumped submillimeter laser lines from CD2Cl2 using a large tunability CW CO2 laser

Twenty-five new laser lines have been obtained in the wavelength region from 155 to 830 μm by optically pumping the CD₂Cl₂ (deuterated dichloromethane) molecule with a CW CO₂ laser having a tunability range of 300 MHz. The wavelength, polarization relative to that of CO₂ pumping radiation, and offset relative to the CO₂ center frequency were determined for all of the new lines and some other already known laser emissions. For all of them we give also the relative intensity and the optimum pressure of operation. Permanent address: Depto de Física e Química da FEIS — UNESP 15.378-000 Ilha Solteira-SP, Brazil     

CO2 laser assisted removal of UO2 and ThO2 particulates from metal surface

Pulsed laser assisted removal of uranium dioxide and thorium dioxide particulates from stainless steel surface have been studied using a TEA CO₂ laser. Decontamination efficiency is measured as a function of laser fluence and number of pulses. Threshold fluence for the removal of UO₂ particulates has been found to be lower than that required for the removal ThO₂ particulates. Usage of a ZnSe substrate, that is transparent to the laser wavelength used here, enabled us to decouple the cleaning effect arising out of absorption in the particulates from that in the substrate and has contributed towards understanding the mechanism responsible for cleaning. The experimental observations are also corroborated by simple theoretical calculations.     

Phase-locking of a multi-channel radial array CO2 laser

A theoretical analysis of phase-locking in a multi-channel radial array CO₂ laser is presented. The concepts are based on the theories of injection phase-locking and matrix optics. The mutual optical coupling occurring within the central region is demonstrated by theoretical deduction. Interrelated graphs of the coupling coefficient and the distance between the coupling position and the cavity mirror are calculated by numerical simulation. The results of the analysis are in accord with experimental results.