共查询到19条相似文献，搜索用时 375 毫秒
1.
本文系统地讨论了脉冲激光烧蚀固体材料时,随激光能量密度的增加,从正常蒸发转变到相爆炸的全过程。首先提出正常蒸发情况下的烧蚀模型,利用此模型,基于Ni靶材,得到激光的透射率随时间的演化规律,以及烧蚀厚度随激光能量密度的变化规律,将所得结果比实验值进行了详细地比较分析,发现我们的结果与实验值达到令人满意的吻合。其次,还讨论了脉冲激光烧蚀靶材时,随激光能量密度变化,烧蚀过程中将出现的亚表面加热,正常沸腾及相爆炸现象。 相似文献
2.
刘丹 《湖北第二师范学院学报》2008,25(8):20-22
本文系统地讨论了脉冲激光烧蚀固体材料时,随激光能量密度的增加,从正常蒸发转变到相爆炸的全过程。首先提出正常蒸发情况下的烧蚀模型,利用此模型,基于Ni靶材,得到激光的透射率随时间的演化规律,以及烧蚀厚度随激光能量密度的变化规律,将所得结果比实验值进行了详细地比较分析,发现我们的结果与实验值达到令人满意的吻合。其次,还讨论了脉冲激光烧蚀靶材时,随激光能量密度变化,烧蚀过程中将出现的亚表面加热,正常沸腾及相爆炸现象。 相似文献
3.
飞秒脉冲激光烧蚀靶材的研究发现,激光和靶材的相互作用不遵守傅立叶定律,热烧蚀模型不再适用。本文首先分析了研究超短脉冲激光烧蚀过程中电子和离子亚系统之间相互作用程度的双温模型,由此出发,结合飞秒脉冲激光的特点,探讨了非平衡烧蚀机理,并根据相应实验数据说明了飞秒激光烧蚀靶材的机制是非平衡态下的烧蚀。 相似文献
4.
研究激光烧蚀水面下的块体锗靶.研究结果表明,激光烧蚀锗的产量(烧蚀率)随锗基板表面水层厚度变化而变化.对单个激光脉冲为60 mJ能量时,烧蚀出的锗溶液浓度在水层为1.2 mm时最高.它揭示在水约束条件下存在一个最优水层厚度,诱导出的等离子体具有最强的冲击力,这种高压、高温等离子体导致最高的烧蚀率.对各水层厚度下烧蚀的锗颗粒粒径做了分析,得到锗纳米粒径随水层厚度增加而单调减少.XRD表明立方单晶锗经激光烧蚀后成为面心立方多晶锗,且含有亚稳相GeO. 相似文献
5.
利用波长532 nm、脉宽10 ns的短脉冲激光在不同激光能量下对甲醛树脂进行了烧蚀推进研究.通过测量激光烧蚀后的靶动量及质量损失,获得激光与甲醛树脂相互作用的动量耦合系数和比冲. 相似文献
6.
在强激光场中,自由电子的运动主要由激光场来支配,我们可以把自由电子看成经典的自由电子,把自由电子的运动看作完全经典的振动,用经典的方法来描述自由电子的运动图像.通过求解经典牛顿运动方程,求出自由电子运动速度的最大值,以求出相应的最大动能. 相似文献
7.
刘丹 《湖北第二师范学院学报》2011,(2):18-19
本文利用双温模型来分析在超短激光烧蚀金靶材的情况下,针对两种不同的脉冲宽度,靶材表面电子及离子温度随时间的变化规律,从而进一步阐明电声相互作用在非平衡烧蚀中所起的作用。 相似文献
8.
本文通过简化自由电子激光实验中的电磁场模式,考虑到电子的自旋态,得到自由电子在旋转磁场中跃迁辐射几率正比于[Si~2(gB O)t/2/(gB o)~2]的结论。 相似文献
9.
建立了一维固体电枢溶化波烧蚀计算模型,采用有限差分法计算电磁场的扩散,得到了溶化波烧蚀速度和烧蚀深度的变化特性。数值计算结果表明,暴露于强磁场环境下的烧蚀表面产生较高的磁场梯度,电流密度集中在烧蚀表面,焦耳热的剧增导致电枢发生烧蚀。将伪烧蚀算法应用于有限差分的计算,证实其不相容。计算结果对溶化波烧蚀问题的理论及试验研究有重要的指导作用。 相似文献
10.
文军 《渭南师范学院学报》1998,(2)
本文对自由电子激光器的工作原理、实验装置以及自由电子激光辐射的基本特征等进行了详细介绍,在系统综述自由电子激光器的发展动态的基础上,指出了这一研究领域的发展趋势． 相似文献
11.
Dynamic Responses Analysis of a Building Structure Subjected to Ground Shock from a Tunnel Explosion
Dynamic responses of a multi-storey building without or with a sliding base-isolation device for ground shock induced by an in-tunnel explosion are numerically analyzed. The effect of an adjacent tunnel in between the building and the explosion tunnel, which affects ground shock propagation , is considered in the analysis. Different modeling methods, such as the eight-node equal-parametric finite element and mass-lumped system, are used to establish the coupling model consisting of the two adjacent tunnels, the surrounding soil medium with the Lysmer viscous boundary condition, and the multi-storey building with or without the sliding base-isolation device. In numerical calculations , a continuous friction model, which is different from the traditional Coulomb friction model, is adopted to improve the computational efficiency and reduce the accumulated errors. Some example analyses are subsequently performed to study the response characteristics of the building and the sliding base-isolation device to ground shock. The effect of the adjacent tunnel in between the building and the explosion tunnel on the ground shock wave propagation is also investigated. The final conclusions based on the numerical results will provide some guidance in engineering practice. 相似文献
12.
Dynamic Responses Analysis of a Building Structure Subjected to Ground Shock from a Tunnel Explosion
TIAN Li LI Zhongxian HAO Hong 《天津大学学报(英文版)》2006,12(B09):100-106
Dynamic responses of a multi-storey building without or with a sliding base-isolation device for ground shock induced by an in-tunnel explosion are numerically analyzed. The effect of an adjacent tunnel in between the building and the explosion tunnel, which affects ground shock propagation, is considered in the analysis. Different modeling methods, such as the eight-node equal-parametric finite element and mass-lumped system, are used to establish the coupling model consisting of the two adjacent tunnels, the surrounding soil medium with the Lysmer viscous boundary condition, and the multi-storey building with or without the sliding base-isolation device. In numerical calculations, a continuous friction model, which is different from the traditional Coulomb friction model, is adopted to improve the computational efficiency and reduce the accumulated errors. Some example analyses are subsequently performed to study the response characteristics of the building and the sliding base-isolation device to ground shock. The effect of the adjacent tunnel in between the building and the explosion tunnel on the ground shock wave propagation is also investigated. T.he final conclusions based on the numerical results will provide some guidance in engineering practice. 相似文献
13.
The loads of shock wave effect on fabricated anti-blast wall and distribution law around the wall were investigated by using near surface explosion test method and FEM.The pressure-time histories and variety law on the foreside and backside of the anti-blast wall were adopted in the tests of variety of different explosion distances and dynamites,as well as in the comparison between the test and numerical calculation.The test results show that the loads of shock wave effect on the anti-blast wall were essen-tially consistent with calculation results using criterion under surface explosion when explosion distances exceed 2 m,the distribution of overpressure behind wall was gained according to variety law based on small-large-small.It is also demonstrated that the peak overpressure behind wall had commonly appeared in wall height by 1.5--2.5 multiples,and the peak overpressures of protective building behind wall could be reduced effectively by using the fabricated anti-blast wall. 相似文献
14.
本文利用经典三维系综模型,研究了超强线偏振激光作用下核间距对氢分子双电离的影响。结果表明,氢分子双电离率随核间距变化。随着核间距的增大,氢分子双电离率先增大,后减小,在R=4a．u．时取得最大值。 相似文献
15.
Test and Analysis of an Existing Tunnel Vibration Induced by Blasting Construction of Diaphragm Wall
YU Guangxi YU Haitao LIU Xian YUAN Yong WANG Qingguo CHENG Guorong WU Xiaofeng 《天津大学学报(英文版)》2008,14(1)
According to the blasting construction of the diaphragm wall of Puxi approaching section of East Fuxing Road river-crossing tunnel,the monitoring project of the vibration of the existing tunnel induced by the blasting construction is put forward,which includes the sensors' location,monitor method and the vibration monitoring system.Based on the monitoring data of the explosion vibration,the vibration wave forms,velocities,acceleration responses,main frequencies and fields of measure points are analyzed under the conditions of three locations and different charge quantities.According to the safety-judging standard of explosion vibration,the conclusion that the existing tunnel is safe under the explosion vibration is then drawn.Furthermore,the spectrum characteristics of three explosion vibrations and the spectrum changing properties of explosion vibration wave transmitting in different directions are concluded,which can provide reference to similar projects. 相似文献
16.
This paper presents surface modifications of aluminum-alloy induced by laser-shock processing (LSP). In the first part, the basic principles are discussed to provide an overview of the physical processes involved in laser shock processing, and to introduce pressure loadings generated by different laser generators. In the second part, emphases are given to the effects of laser intensity, target material, laser pulse duration and laser wavelength, and uniform and localized modeling of fatigue behavior after LSP. In the third part,experimental results are given to show the laser-induced pure mechanical effects on aluminum-alloy by using LSP. 相似文献
17.
温吉华 《洛阳师范学院学报》1999,(2)
研究了在相对论领域中,氢原子在强激光场中的电离几率变化规律和向外辐射出的高次谐波之间的关系,得出了在氢原子电离几率大时的激光条件下辐射出的高次谐波多。电离几率小时的激光条件辐射出的高次谐波少。 相似文献
18.
Laser shock processing (LSP), also known as laser peening, is a novel surface treatment technique in the past few years. Compressive
residual stresses which imparted by LSP are very important for improving fatigue, corrosion and wear resistance of metals.
Finite element analysis (FEA) simulation using ABAQUS software has been applied to predict residual stresses induced by LSP
on Ti-6Al-4V titanium alloy with laser pulse duration 30 ns and water confined ablation mode. The residual stress field generated
by different shape laser spots was studied, and the square laser spot is shown the most suitability for avoiding stress lack
phenomenon and overlapping LSP. Surface residual stresses and plastically affected depth within single square spot both increased
with the increase of laser intensity and laser shock times. Furthermore, compared with circle and ellipse spot, the residual
stress distribution in overlapping square spots is very uniform only with small overlapping ratio. LSP with square spot can
process advantageous residual stress field, and this technique will be used widely. 相似文献
19.
用高能量钕玻璃激光器烧蚀光谱标钢获得等离子体，以氩气作为保护气体，分析了LTSD(Len To Sample Distance，激光器透镜到样品表面的距离)和环境气压对等离子体激发温度的影响．结果表明，当激光束焦斑围绕样品表面上下移动时，等离子体激发温度的分布具有不对称性：当焦斑样品表面以下0．4mm左右时，等离子体的激发温度接近最大值；随着环境气压的增大，等离子体的激发温度明显增强． 相似文献