神光II升级项目终端靶场优化设计研究
文献类型：学位论文
| 作者 | 乔战峰 |
| 学位类别 | 硕士 |
| 答辩日期 | 2008 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 朱宝强 |
| 关键词 | 高功率激光装置 靶场终端系统 终端光学组件 导光反射镜 真空靶室 靶室中心参照系统 有限元分析 |
| 其他题名 | The optimizing design for target area system in SGII-U |
| 中文摘要 | 高功率激光装置作为光机电一体的大型精密光学设备，主要用于惯性约束聚变（Inertial Confinement Fusion，ICF）研究。作为物理实验的实施场所，靶场系统需要保证各路激光按照要求高精度地作用于靶面。一般来说，ICF物理实验要求高功率激光装置具有高质量的焦斑性能和激光弹着点控制精度。影响焦斑性能的主要因素是波前畸变，通常使用自适应光学系统予以校正。但是，由于变形镜的校正范围有限，而高功率激光放大链中光学元件数量又很庞大，尤其是靶场系统光路复杂，使用的大口径光学元件（特别是大口径反射元件）数量众多，如不加以控制，焦斑性能难以得到保证。影响激光弹着点精度的因素较多，对于靶场系统来说，主要受到大口径光学元件稳定性以及靶定位瞄准监视系统光学分辨率的限制。而提高光学元件稳定性主要依靠优化机械调整架及其支撑系统（包括桁架和靶室等）设计来实现。 本论文正是针对上述因素，在神光II升级项目靶场分系统的设计中，通过对靶场中关键元器件的优化设计，以提高焦斑性能和激光弹着点控制精度，使其满足系统设计的要求，为项目的顺利实施提供必要的设计参考数据。 由于神光II升级项目为了提高激光器件的工作效率和节约工程成本，激光束采用正方形光束。我们通过立体几何与三维仿真设计相结合的方法得出了神光II升级项目八路纳秒脉冲在传输到终端光学组件时的旋转角度为：第1、4、6、7路光束旋转角度为顺时针旋转23.95°；第2、3、5、8光束旋转角度为逆时针旋转7.42°。 导光反射镜是终端靶场系统完成激光导引的最主要光学元件，其表面装夹变形直接影响到激光的波前分布。项目总体设计指标要求靶场单块反射镜的整体装夹变形量δ≤λ/6（λ＝0.6328μm）。通过有限元分析软件，运用有限元静力学方法对神光II升级项目终端靶场导光反射镜在不同装夹方式下的静力变形进行了分析。最终确定了每一块导光反射镜的装夹方式以及最佳镜片厚度。 真空靶室作为高功率激光与物质的作用场所，其设计的准则是要具有高稳定性和小的应力变形。我们首先运用有限元静态分析方法对神光II升级项目真空靶室进行分析，了解到在安装有终端光学组件的真空法兰与真空靶室连接处出现比较大的应力集中。通过应力卸载的方法，使得局部应力集中得到了改善。通过输入激励载荷对真空靶室进行了频谱分析，得出由靶镜稳定性产生的激光弹着点精度误差为1.18μm，满足系统要求的靶镜瞄准误差小于1.9μm的设计要求。 作为直接影响到靶瞄准精度的靶室中心参照系统（简称CCRS）来说，不但要求其有较长的工作距离和高的光学分辨率，还要具有角分辨率功能。由于市场上并没有满足要求的成熟产品，我们通过对Questar显微望远镜的改造设计，增加了望远镜的角分辨率功能。并对其进行了技术指标测试。 本文通过对靶场系统中影响到激光波前分布和激光弹着点控制精度的关键因素的分析，确定了：1.八路方形纳秒脉冲在传输到终端光学组件处的旋转角度；2. 影响到激光的波前分布的靶场导光反射镜的装夹方式和最佳镜片厚度；3. 真空靶室的结构设计准则；4. 关系到靶瞄准精度的CCRS系统中的望远镜的改进设计。 关键词：高功率激光装置，靶场终端系统，终端光学组件，导光反射镜，真空靶室，靶室中心参照系统，有限元分析 |
| 英文摘要 | The high power laser facility is a high precise optical instrument, and mostly be used for Inertial Confinement Fusion (ICF). For the requirements of physical experiments, target area system must ensure that each laser beam should be conducted to the target accurately. In general, physical experiments require high-performance laser focus, high accurate laser alignment and target position. The wave-front distortion will affect the distribution of focus, which could be corrected by adaptive optical system. But on the one hand, the adjusted range of deformable mirror is limited. On the other hand, there are so many optical elements used in high power laser facility. Particularly in target area, in order to realize high precision beam conduction, lots of large-aperture optical elements (especially lots of large-aperture reflector) are used, which would increase wave-front aberration significantly. So the quality of optical elements must be controlled. There are many factors to influence the accuracy of laser alignment and target position. In target area system, the stability of large-aperture optical elements and the optical resolution of monitor system are two key factors. Fine stability of the optical elements depends on the optimizing design for mechanical framework and support system (mirror support structures and target chamber etc). In this paper, aimed at requirements mentioned above, we optimize the key element in target area to improve the performance of the laser focus, the accuracy of laser alignment and target position. In order to improve performance-cost ratio of SGII-U facility, the shape of laser beam is square. By using solid geometry and 3-D design, we have obtained the circumvolving angle of each laser beam at the Final Optical Assembly (FOA): the 1st, 4th, 6th, 7th beam circumvolving angle are 23.95 degree in clockwise direction, and 2nd, 3rd, 5th, 8th beam circumvolving angle are 7.42 degree in counter-clockwise direction. The reflector is the important optical element to conduct the laser beam into target chamber in target area. The deformation of its surface caused by assembly and gravity will lead to increasing of wave-front distortion. By analysis, the deformation of each reflector’s surface must be less than λ/6 (λ=0.6328μm) in target area system. Finite element analysis has been used to evaluate different assembling mode of reflector in static state. Finally we have obtained the best assembling mode and optimal thickness for each kind of reflector. Target chamber is the place of physical experiments. It should have high stability and small stress distortion. Firstly, Finite element analysis has been used to evaluate target chamber of the SGII-U in static state, the results shows that the stress on the joint between the target chamber and the flange of the FOA is very high. By means of optimal design, the stress has been decreased. Secondly, by PSD analysis with dynamic power of environment, we find out that the accuracy of laser alignment caused by stability of target lens is 1.18μm, which could satisfy the requirment. The Chamber Central Reference System (CCRS) is the key device for target position. It has not only long work distance, but also high optical resolution and angle resolution. Because there isn’t ready-mode product in market, we upgraded Questar telescope. And measurement result shows it could satisfy the requirements. In this paper, we have analyzed a few key elements that affect the wave-front distortion and the accuracy of laser alignment and target position, and obtain some results: 1)the circumvolving angle of each laser beam at FOA, 2)the best assembling mode and optimal thickness of the reflector, 3)the rules of target chamber’s structure design, 4)upgrading design of Questar telescope for the CCRS. Key words: the high power laser facility, target area system, FOA, reflector, target chamber, CCRS, the finite element analysis. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16652]  |
| 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 | 乔战峰. 神光II升级项目终端靶场优化设计研究[D]. 中国科学院上海光学精密机械研究所. 2008. |
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。