高功率XeCl准分子激光自发辐射放大的三维计算

 采用M – C方法计算了强流电子束泵浦XeCl准分子激光输运过程中生成的放大自发辐射（ASE）在激光腔中的输运过程。该模型考虑了腔壁的反射影响、非饱和吸收和镜反射的作用，计算给出最佳注入通量值。计算结果与文献[2] ~ [5] 给出的理论及实验结果相吻合。可为准分子激光实验提供理论依据和实验参考。并可推广到任何类型的激光器。     

磁约束放电CO激光模型

建立了磁约束放电CO激光的模型.在该模型下分析、计算了CO气体放电系统电子的能量分布 函数;CO分子的电子碰撞激发概率以及CO分子的振动-振动(V-V),振动-平动(V-T)激发概率 ;CO分子各振动态的布居数分布和对应的小信号激光增益系数.研究表明,由于磁场的加入C O分子振动态布居数分布出现凹陷.在该区域获得了更大激光的小信号增益. 关键词： CO激光 磁约束 布居数 小信号增益 激发系数     

电子束泵浦XeCl准分子激光器及应用

为了获得高能紫外激光输出,开展了电子束泵浦XeCl准分子激光技术研究。详细介绍了四向电子束泵浦准分子激光装置的工作原理和结构特征,简述Marx发生器的放电电压、放电电流,激光气室中的沉积能量,激光脉冲能量、脉宽等参数的测量方法;研究了电子束泵浦XeCl准分子激光输出特性,得到了激光脉冲能量随激光气室内混合气体气压变化的规律,当激光器的充电电压为81kV时,获得了能量100J、脉宽200ns的XeCl准分子激光输出,其本征效率约为3.2%。并且开展了XeCl准分子激光辐照涂层材料力学特性研究,采用微型红外通光冲量探头测量不同条件下激光辐照涂层材料的冲量耦合系数,在常压空气环境中的冲量耦合系数约为8.32×10-5 N·W-1。     

电子泵浦KrF准分子激光的一维动力学研究

对电子束泵浦KrF准分子激光进行了一维动力学模拟研究,考虑了24种粒子,119种反应通道。较为细致地研究了一维模型的物理机制及数学处理方法。运用该模型对国外实验结果作了模拟计算,结果符合较好。对原子能院电子束泵浦百焦耳级准分子激光器进行了模拟计算,给出了一些激光参数随时间、纵向位置的变化规律。最后对零维模型和一维模型的计算结果作了比较。     

BFEL激光能量的计算

 为进一步提高BFEL的小信号增益和确定激光能量等性能参数，用定态和非定态程序对BFEL激光的能量进行了计算和分析。计算结果表明:采取适当措施，将电子束的发射度由50 pmm·mrad降低到30 pmm·mrad，电子束宏脉冲宽度由5.0 ms增加到6.5 ms，激光传输效率由40%增加到80%，BFEL的小信号增益将由16%增大到28%，输出激光的能量也将提高近一个量级。     

KrF激光器空间非均匀抽运动力学模拟

提出了模拟KrF激光器的三维动力学方法.该方法与以往的动力学方法的主要区别在于考虑了电子束抽运的空间非均匀性.即将电子束抽运速率作为空间各点(X,Y,Z)及时间(t)的函数.用三维模拟方法对96101702实验进行了计算.总的激光输出及镜面能量分布与实验符合相当好.解决了以往模型理论明显高于实验的问题 关键词： KrF激光器 三维动力学模型 电子束抽运     

XeCl准分子激光器

本文介绍我们对XeCl准分子激光器的实验结果. 在国外,第一台XeCl准分子激光器于1975年制成,激励源是相对论电子束,仅获得50微焦耳能量输出[1].1977年苏联用快速放电得到1毫焦耳输出,效率为0.05%[2].这样XeCl准分子体系便因其效率低、输出小,难于实现振荡而被忽视.但最近有人采用HCl作Cl施主,在紫外光预电离的诀速放电器件中获得了110毫焦耳[3]输出,效率为0.8%,达到与XeF、KrF同等水平,证明了获得高效率、高功率的可能性,重新为人们重视起来. 迄今,已报导的快速放电XeCl激光器采用做口施主的有:Cl2:、CF3Cl、C2F3Cl、CCl2F2、CCl4…     

宽频带聚焦泵浦准稳态受激电子喇曼散射的增益因子和能量转换效率

本文采用Raman-Maxwell-Bloch方程,计算了宽频带聚焦泵浦准稳态受激电子喇曼散射的增益因子和能量转换效率.在计算中考虑了泵浦抽空、喇曼介质对泵浦光的吸收和喇曼介质的泡和效应.计算结果与XeCl激光在钡蒸汽中的受激喇曼散射实验基本上符合.     

XeCl激光诱导的CS_2多光子电离质谱

本文报道了CS_2在XeCl准分子激光(波长为308nm)诱导下的多光子电离质谱实验.我们测量了各种离子(S~ 、CS~ S_2~ 和CS_2~ )强度相对激光强度和样品气量的变化规律,根据这些结果和一些相应的计算确立了CS_2多光子电离的动力学模型和每一种离子的具体生成过程.     

自由电子激光放大器的小信号理论

本文根据单粒子模型阐述了自由电子激光放大器的工作原理,通过将电子运动方程线性化导出了小信号增益。结果表明,当电子束有合适的初速分布,周期静磁场和入射电磁波有确定的相位关系,并且满足电子与波的同步条件和电子回旋谐振条件时,电子能持续地和最有效地将能量交给入射电磁波,从而实现激光放大。     

Method for determination of co-spectral gain and absorption coefficients in high-power lasers

A new method is described for determining the small-signal gain and non-saturable absorption coefficients over the same spectral region for high-power lasers. Preliminary tests of this method on the discharge-pumped XeCl excimer laser have yielded B²σ→X²σ gain coefficients which are comparable to those observed in other experiments under similar excitation conditions. However, the absorption coefficient is found to be a high and nearly constant fraction (~$\text{1}\text{4}$) of the gain. This result suggests that all of the absorption processes are due to excited species, including XeCl B²σ.     

电子束泵浦百焦耳级准分子激光实验研究

利用“闪光二号”相对论电子束加速器研制了百焦耳级ＸｅＣｌ和ＫｒＦ准分子激光器，激光器激活体积２４ｌ，输出口径２０×２０ｃｍ２，泵浦功率密度１．５～２．０ＭＷ／ｃｍ３。ＸｅＣｌ激光器最大能量１３６Ｊ，波长３０８ｎｍ，脉宽５０～１００ｎｓ，峰值功率１．５ＧＷ，采用虚共焦非稳腔技术，束散角达１．３ｍｒａｄ；ＫｒＦ激光最大能量１５７Ｊ，波长２４８ｎｍ，脉宽８０～１００ｎｓ，峰值功率２ＧＷ。     

Comparison of characteristics of an x-ray preionized XeCl laser, pumped by water transmission line and low inductance capacitor bank

With a high uniformity of x-ray preionization, a long pulse duration and a high specific energy (9 J l^-1), an XeCl excimer laser output has been obtained by using a compact low inductance capacitor bank as the laser excitation circuit. The superior features of the low inductance capacitor bank (LICB) compared to the water transmission line (WTL) are attractive for repetitively pulsed XeCl excimer lasers.     

Theoretical modeling of microwave-pumped high-pressure gas lasers

The electron avalanche and laser excitation processes in high-pressure discharges at microwave frequencies are investigated. In our model, the applied electromagnetic field is treated classically and assumed to be monochromatic. The Boltzmann equation for the electron velocity distribution function under the influence of an alternating electric field is numerically solved for a typical XeCl laser gas mixture. All relevant elastic, inelastic and electron-electron collisions are included in solving the Boltzmann equation. The theoretical modeling of microwwave-pumped high-pressure gas lasers are developed based on the first law of thermodynamics in order to determineE _rms/n (root-mean-square field strength/total number density of gas molecules) which is required by the Boltzmann equation to calculate the electron kinetics rates and microwave-power absorption by the plasma. A sample calculation of the microwave-pumped XeCl laser is presented, and a fair agreement between theory and experiment is seen.Paper partially presented at the 10th Int. Conf. on Lasers and Applications, Lake Tahoe, Nevada, USA (1987)     

Laser isotope separation of carbon by multiple IR photon and subsequent UV excitation of CF3I molecules

A new approach to laser isotope separation is considered. It is based on collisionless multiple photon ir laser excitation and subsequent uv laser dissociation of vibrationally excited molecules. TEA CO₂ and excimer XeF, XeCl lasers are used for ir excitation and uv dissociation, respectively. The products of photolysis (C₂F₆) are enriched with¹²C.     

Influence of the laser wavelength on the epitaxial growth and electrical properties of La0.8Sr0.2MnO3 films grown by excimer laser-assisted MOD

Epitaxial La_1−xSr_xMnO₃ (LSMO) films were prepared by excimer laser-assisted metal organic deposition (ELAMOD) at a low temperature using ArF, KrF, and XeCl excimer lasers. Cross-section transmission electron microscopy (XTEM) observations confirmed the epitaxial growth and homogeneity of the LSMO film on a SrTiO₃ (STO) substrate, which was prepared using ArF, KrF, and XeCl excimer lasers. It was found that uniform epitaxial films could be grown at 500 °C by laser irradiation. When an XeCl laser was used, an epitaxial film was formed on the STO substrate at a fluence range from 80 to 140 mJ/cm² of the laser fluence for the epitaxial growth of LSMO film on STO substrate was changed. When the LaAlO₃ (LAO) substrate was used, an epitaxial film was only obtained by ArF laser irradiation, and no epitaxial film was obtained using the KrF and XeCl lasers. When the back of the amorphous LSMO film on an LAO substrate was irradiated using a KrF laser, no epitaxial film formed. Based on the effect of the wavelength and substrate material on the epitaxial growth, formation of the epitaxial film would be found to be photo thermal reaction and photochemical reaction. The maximum temperature coefficient of resistance (TCR) of the epitaxial La_0.8Sr_0.2MnO₃ film on an STO substrate grown using an XeCl laser is 4.0%/K at 275 K. XeCl lasers that deliver stabilized pulse energies can be used to prepare LSMO films with good a TCR.     

Excited singlet-state absorption in laser dyes at the XeCl wavelength

The transmission properties of the laser dyes BBQ, PBD, BPBD, -NPO,p-Quarterphenyl and PPO have been measured using a XeCl (308 nm) excimer laser. A model for the dye saturation which incorporates excited-state absorption was used to estimate the lifetime and the absorption cross section of the first excited singlet-state for each dye.     

低真空下紫外激光烧蚀铜诱导发光的机理

采用时间与空间分辨的光谱测量技术,测量了在低真空下XeCl紫外激光烧蚀金属Cu诱导产生等离子体发光羽的发射光谱随时间和空间的强度分布,利用快速同步照相的方法获得了发光羽的相片,结果发现发光羽的不同区域有不同的颜色特征。根据实验结果建立了非常可能的激光烧蚀诱导发光的理论模型,认为不同区域的主要发光机理不同,连续辐射背景光来自近靶处高能电子的运动而产生的轫致辐射;原子线的产生来自电子碰撞传能以及电子与离子的复合激发;离子线的产生来自电子与离子碰撞传能激发。此模型不仅能解释单一激发模型所能解释的实验现象,而且还能够很好地解释单一模型所不能解释的实验现象,低真空下紫外激光烧蚀铜诱导发光的机理与常压下相似,在此实验条件下可以更准确地揭示诱导发光的机理。