Simulation studies of the prepulse-main-pulse XeCl discharge lasers with magnetic switching

A self-consistent model of a self-sustained discharge XeCl laser (Ne/Xe/HCl mixture) with prepulse-mainpulse excitation and magnetic switching which leads to high efficiency operation is described. The validity of the model is confirmed by comparing the results of the calculations with the measured time dependences of discharge voltage, current and lasing pulse for different operation modes as well as by comparing the results with the dependences of the laser output energy and efficiency on the charging voltage and capacitance of the pulse forming network for two different laser heads. The numerical evaluation has shown that our developed laser system operates under optimum conditions.     

C-C转移放电泵浦XeCl准分子激光器能量沉积特性的分析

本文报道了一台使用UV自动预电离,C-C转移放电泵浦的XeCl准分子激光器,并且以激光器放电信号和输出激光信号的同时测量结果为依据,分析了激光器放电的能量沉积过程.可为设计同类型准分子激光器提供一些参考数据.     

同步触发对多电极对激光器输出特性的影响

在研究多电极对激光器输出特性的实验中,在气压、脉冲电压、放电区体积等其他放电参数保持不变的情况下,多组电极对同步触发时,激光器的输出有非线性的脉冲能量增强效应。在总结实验规律的基础上,综合考虑腔内光子数密度和谐振腔效率的影响,深入分析非线性能量增强效应的产生机制,建立了理论模型。将理论计算值与实验测量值相比较,理论分析与实验结果符合较好。     

A new mode to excite a gas-discharge XeCl laser

The charge mode is a new mode to excite a discharge XeCl laser based on the dynamics of a spiker-sustainer circuit with a magnetic pulse compressor. The breakdown voltage is higher than in any other mode, due to a very fast rise time. The higher breakdown voltage provides a wider discharge and we found that more energy can be deposited before discharge instabilities terminate the optical output.     

放电激励重复频率非链式HF激光器

 利用紫外预电离横向放电和气体循环结构建立了一套放电激励重复频率HF激光装置。研究了激光器工作介质SF6/C2H6混合气体放电特性和激光输出特性,获得激光器单次运行的最佳输出参数;通过对激光器重复频率运行时不同气体流速、充电电压与气体总压条件下的放电状态和输出能量的比较,分析了激光器重复频率稳定运行的必要条件。结果表明：所研制的激光器最大单脉冲能量0.6 J,峰值功率3 MW,电光转换效率2.4%;当混合气体工作介质以3.5 m/s的流速循环时,激光器稳定运行的最高工作频率可达50 Hz,脉冲输出能量稳定在0.26 J,平均功率达到13 W。     

表面放电等离子体产生冲击波特性

采用压力传感器,分析XeF(C→A)激光器高电压表面放电光泵浦方式不同位置、不同放电电压条件下冲击波特性。研究结果表明,表面放电等离子体膨胀产生的冲击波持续时间为ms量级,在冲击波过后伴随有相对较弱的压力波。随着充电电压增加,放电过程释放能量增多,冲击波峰值压强也变大,最大压强可达1 MPa,同时冲击波峰值延后,冲击波持续时间变长。     

Electro-optically Q-switched lasers with polarization output coupling and their pulse control

We present a design of E/O Q-switched laser with polarization output coupling. Based on laser rate equations, we analyzed pulse control of this type of laser. A model of laser pulse generating is set up. The relationship between pulse energy and high voltage values is given in this model. The experiments have been carried out. The result fits the theoretical model well.     

0.73 J脉冲能量KrF准分子激光器的特性

研制了一台KrF大能量准分子激光器,激光器采用紧凑型Chang电极与紫外火花预电离的结合, 实现了激活区大面积的均匀辉光放电,利用LC反转倍压以及一级磁脉冲压缩技术在放电电容上实现了峰值电压40 kV、脉冲上升时间约为100 ns的高压快脉冲激励。研究了工作气体含量对激光器能量输出的影响,在总气压3.3105 Pa,F2/He, Kr, Ne体积分数比值为1.97∶3.18∶94.85,充电电压27 kV时,得到了738 mJ的单脉冲能量输出,激光近场光斑30 mm14 mm,在充电电压23 kV时,全电效率最高,达到2.0%。     

High power repetitive TEA CO2 pulsed laser

A high power repetitive spark-pin UV-preionized TEA CO₂ laser system is presented. The discharge for generating laser pulses is controlled by a rotary spark switch and a high voltage pulsed trigger. Uniform glow discharge between two symmetrical Chang-electrodes is realized by using an auto-inversion circuit. A couple of high power axial-flow fans with the maximum wind speed of 80 m/s are used for gas exchange between the electrodes. At a repetitive operation, the maximum average output laser power of 10.4 kW 10.6 ??m laser is obtained at 300 Hz, with an electro-optical conversion efficiency of 15.6%. At single pulsed operation, more pumping energy and higher gases pressures can be injected, and the maximum output laser energy of 53 J is achieved.     

Plasma cathode TEA Ar laser development

The plasma cathode design concept is applied to an Ar laser for the first time. The sliding discharge is used as a plasma cathode for the main laser discharge. The laser operates at atmospheric pressure with a gas mixture of Ar/He/SF₆. Results concerning the dependence of the laser performance on the gas mixture flow rates and charging voltage are presented. The temporal behavior of the laser output is also presented. Output energies as high as 2 mJ, efficiency and specific energy extraction values up to 1.3×10⁻²% and 0.02 J/l respectively, at atmospheric pressure, are obtained. The spectroscopic examination of the output shows that lasing at 1.79 and 1.27 μm is obtained with approximately equal line intensities.     

电泳式He-Sr+复合激光特性研究

设计制作了7mm内径和38cm有效激励长度的电泳式He-Sr⁺激光管,采用修饰Blumlein电路,通过纵向高重复率脉冲放电激励,实现了一价锶离子复合激光430.5nm和R-M跃迁激光1.03μm的同时振荡,其中复合激光占主要成分.测量分析了复合激光输出功率与工作参量(脉冲频率,充电电源电压和氦压)的关系曲线.获得了最大激光功率819mW和56mW/cm³功率密度的实验结果. 关键词： 锶离子激光 电泳 脉冲放电     

Performance improvement of an x-ray preionized XeCl laser of very small discharge volume

Increasing the preionization electron density is found to be an effective method for improving the output performance of discharge-pumped excimer lasers at high gas pressures when the power-supply voltage becomes a limiting factor. In a small volume (2 cm³), x-ray preionized discharge, orders of magnitude improvement in XeCl laser power output (up to 400 kW) and pulse energy (up to 26 mJ) over previously reported results have been found possible using this method. Modifications to the low energy x-ray source and discharge system leading to these improvements are described. Various laser output characteristics are also presented and discussed.     

Laser dye stability,part 12. The pyridinium salts

Improved laser output is demonstrated in KrF and XeCl lasers with x-ray preionization. The influence of gas composition, preionization geometry, x-ray dose,E/p value and temporal delay between x-ray pulse and laser discharge is discussed. In XeCl lasing has been achieved with an x-ray dose of 0.2 mR whereas approx. 3 mR are required for KrF. For both systems, the highest output energy and the lowest possibleE/p ratio were observed with Ne buffered gas mixtures. Dissociative attachment to halogen molecules on a ns time scale supported by a relatively slow laser voltage rise is recognized as the main electron loss channel preventing a long lifetime of the preionization electrons. High preionization intensity is thus desirable at the moment of voltage breakdown.     

电激励脉冲HF激光SF_6/C_2H_6工作气体的放电特性

研究了电激励脉冲HF激光工作介质SF6/C2H6混合气体的放电特性。通过对放电等离子体荧光图像和放电波形的测量,分析比较了不同条件下放电稳定性、剩余电压、能量沉积效率等特性参数的变化情况。实验结果表明:混合气体的放电过程存在主放电、剩余电压维持和电弧放电3个阶段,各阶段的放电特性有所差异;提高充电电压有利于放电能量的有效沉积,也会使不稳定的电弧放电提前;增加C2H6原子分数能起到抑制电弧放电的作用;混合气体总压的增加会导致剩余电压的提高以及辉光放电的能量沉积效率的降低;最佳的能量沉积出现在电弧放电阶段与辉光放电阶段即将融合的临界状态。     

Characteristics of a Cataphoresis He-Ca+ Recombination Laser

A cataphoretic input of calcium vapour into the active volume of pulsed He-Ca^＋ laser is designed and made. The recombination laser at 373.3 nm and the R-M transition laser at 854.6 nm are achieved experimentally with modified Blumlein circuit by high-frequency longitudinal pulsed discharge. The dependences of work parameters such as the pulse frequency, the power supply voltage and the helium pressure on laser output characteristics at 373.3nm line are measured and discussed. The maximum laser output power of 136mW and the specific power of 5.9 m W/cm^3 are obtained, respectively.     

Modeling the plasma kinetics mechanisms of CuBr laser with neon–hydrogen additives

A mathematical model describing the discharge kinetics and lasing characteristics of copper bromide vapor laser with neon and hydrogen additives has been developed. The suggested model is based on a “zero-dimensional” model and offers simple mechanisms to explain discharge kinetics mechanisms, different physical processes and hydrogen additive effects on the copper bromide vapor laser.The model estimates the temporal evolution of discharge voltage and current, population densities, laser beam density, electron temperature and radial distribution of pressure and buffer gas temperature. The suggested mechanism assumes that the electron detachment from negative hydrogen ions does not contribute to the copper ionization process.Numerical solutions of a nonlinear rate equation system predict the generation of nanosecond pulses. The calculated maximum values of discharge voltage, current, average output laser power, electron temperature, etc. are in good agreement with other reported calculated and experimental data.     

用于ps脉冲放大的大口径放电泵浦KrF激光器

 以简单的火花间隙作为放电开关，建立了一种用于ps脉冲激光放大的大口径放电泵浦KrF准分子激光器。该激光器的有效增益口径截面为4cm×3cm，在自由运转情况下最大激光输出能量为1.3J，脉宽20ns。用作ps放大器时，利用光学偏振放大方式获得了激光能量140mJ，脉冲宽度10ps的激光输出。利用XeCl激光泵浦的染料激光作为探针测量了不同放电条件下和不同气分比条件下激光的增益和吸收系数。     

Design and performance characteristics of a krypton chloride (λ = 222 nm) excimer laser

Development of a discharge-pumped krypton chloride (KrCl) laser operating at 222 nm wavelength is demonstrated. In this paper the design, successful realization and operating characteristics of KrCl excimer laser are reported. The laser is driven by a simple and efficient excitation technique using automatic UV pre-ionization with discharge-pumped self-sustained capacitor–capacitor (C–C) energy transfer circuit. The experimental investigations including output laser energy, temporal pulse parameters, emission spectra and beam profile of the KrCl laser were recorded. For high repetition rate operation, in-built, compact gas circulation system using tangential blower was incorporated. The laser was operated at 25 kV discharge voltage, gas mixture of 5 mbar HCl, 160 mbar kypton and neon as balance with a total gas pressure of ～2.5 bar. These experiments produced an efficient and reliable output energy of 25 mJ from an active volume of 60 cm³.     

Observation of vacuum-ultraviolet Kr(2)* laser oscillation pumped by a compact discharge device

We have demonstrated vacuum-ultraviolet (VUV) Kr(2) * laser oscillation as a result of the realization of a stable self-sustained discharge of high-pressure Kr by use of a compact discharge device. Glow discharge was obtained with as much as 10 atm of pure Kr. The VUV emission intensity centered at 147.8 nm abruptly increased when the charging voltage exceeded a certain value. In addition to this threshold behavior, considerable spectral narrowing (4.0?0.4 nm) was observed when the charging voltage increased. The maximum output energy at 148 nm was 150muJ . The gain coefficient was estimated to be 1.1% cm (-1) .     

Long-pulse KrCl laser with a high discharge quality

The discharge quality and optimum pump parameters of a long-pulse high-pressure gas discharge excited KrCl laser are investigated. A three-electrode prepulse–mainpulse excitation circuit is employed as pump source. The discharge volume contains a gas mixture of HCl/Kr/Ne operated at a total pressure of up to 5 bar. For a plane–plane resonator, the divergence of both output laser beams is measured. A low beam divergence of less than 1 mrad is measured as a result of the very high discharge homogeneity. A maximum laser pulse duration of 150 ns (FWHM) is achieved for a pump duration of 270 ns (FWHM) and a power density of 340 kW cm^-3. Pumping the discharge under optimum conditions employing a stable resonator results in a maximum specific energy of 0.45 J/l with a laser pulse duration of 117 ns and an efficiency of 0.63% based on the deposited energy. PACS 42.55.Lt; 52.25.-b; 52.59.Ye