超短强激光脉冲传输的有关问题研究
文献类型：学位论文
| 作者 | 张向东 |
| 学位类别 | 硕士 |
| 答辩日期 | 2002 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 王晓方 |
| 关键词 | 啁啾脉冲放大技术 超短强激光 等离子体 尾波场 |
| 其他题名 | Study on Some Problems Related to the Propagation of Ultrashort Intense Laser Pulses |
| 中文摘要 | 该论文主要对利用CPA技术产生强激光超短脉冲及激光脉冲与物质相互作用进行研究.主要的研究成果有1、展宽器群速度色散的几何光学方法分析;展宽器是CPA技术中重要的组成部分,目前常用的展宽器是Martinez于1987年提出的,以及在此基础上改进的各种展宽器.Martinez还用Fresnel-Kirchhoff积分方法分析了他所提出的展宽器(即在一对反平行光栅之间放置折射式望远镜系统)产生的正色散,并给出了相应的群速度色散表达式.我们利用几何光学的方法,分析并推导了Martinez展宽器和其它几种典型的光栅展宽器的群速度色散,给出了解析表达式.结果与Martinez得到的结果一致.2、激光尾波场激发的数值研究;当强激光脉冲在稀薄等离子体中传播时,激光脉冲作用在等离子体上的有质动力使之形成空间电荷分离,在激光脉冲的后面产生等离子体波,即尾波场.利用尾波场的大加速梯度电场可以用来加速电子,我们用一维粒子模拟程序LPC++研究了相对论强度超短激光脉冲与稀薄等离子体相互作用尾波场的激发,给出了尾波场的峰值振幅与激光脉冲宽度之间的关系.当激光脉冲宽度与等离子体波波长相当时,尾波场激发机制为共振激发,而且所得结果与用准静态近似下的一维非线性方程得到的结果一致.当激光脉冲宽度继续增大时,准静态近似不再适用,尾波场激发的机制转变为自调制激发.3、激光在柱状折射率分布的介质中的传播;强激光脉冲在等离子体中传播时,等离子体可以形成对激光脉冲具有导引作用的波导,以及利用毛细管增加作为产生X射线激光增益介质的等离子体的有效长度等等,这些都可归结为光在纤维状介质中传播规律的研究.我们利用光线追踪方法在近轴近似的条件下模拟了高斯光束在不同折射率分布的纤维状介质中的传播,并针对等离子体对激光的导引现象以及操纵粒子的空心环状光束的产生进行了模型化分析和讨论. |
| 英文摘要 | The laser technology was well developed since the first laser made its debut in 1960.In past few years, the output power of laser reached terawat to petawatt in laboratory because of the invention of chirped pulse amplification technique. The field of such high-intense pulse is much greater than the Coulomb field binding the ground state electron in the hydrogen atom, which gives researchers the power to control the movement of the electron in matters and change the properties or phase of matters. This new development brings the chance and challenge to the astrophysics, material sciences, plasmas sciences, laser fusion, nonlinear optics, relativity physics, condensed matter physics, laser physics, high power physics and other subjects. This thesis involved the work as following aspects: 1-, Analysis of Group Velocity Dispersion of Typical Stretchers by Means of Geometric Optics. Stretcher is one of most important components of chirped pulse amplification technique. The stretchers widely used in laser facilities are the one proposed by Martinez and improved versions. Martinez analyzed the positive dispersion produced by stretcher and gave the expression of it with Fresnel-Kirchhoff integral. We analyzed the group velocity dispersion by means of geometric optics. The analytical formulae of group velocity dispersion are given, which are consistent with Martinez's result. 2-, Numerical Study of Wake Field Induced by Ultra-Intense Laser Pulse. When a short intense laser pulse propagates in an under-dense plasma, plasma electrons are expelled by a ponderomotive force of laser pulse. Hence the charge separation is induced, which generates a wake wave behind the intense laser pulse. The electrical field of wake wave is longitudinal field with sharp gradient and can be used to accelerate electrons. We numerically studied the wakefield generation using particle-in-cell simulation. The relationship between maximum amplitude of wakefield and laser pulse width was given. The result is consistent with which was obtained by using nonlinear theory under quasistatic approximation when the pulse width is close to the wavelength of plasma wave. When the pulse width increases, the wakefield is generated by self-modulation of the laser pulse. 3 The Analysis of the Propagation of Light in Media with Cylindrical Refractive Index Distributions. When high intense laser pulse travels in plasma, laser pulse can be guided by plasma waveguide. The laser pulse propagates in capillary, which is used to lengthen the effective length of gain material, plasma, to generate X ray. All above can fall into the study of propagation of light in fiber matters. We analyzed the propagation of a Gaussian beam in fiber media with ray tracing under the paraxial approximation. Using different refractive index distributions, we discussed the phenomena of plasma waveguide and the application of a ring-shaped beam in the manipulation of particles, separately. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16586]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 张向东. 超短强激光脉冲传输的有关问题研究[D]. 中国科学院上海光学精密机械研究所. 2002. |
入库方式： OAI收割
来源：上海光学精密机械研究所
浏览0
下载0
收藏0
其他版本
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。