甚多束阵列式激光放大技术研究
文献类型：学位论文
| 作者 | 陈亚林 |
| 文献子类 | 硕士 |
| 导师 | 王江峰 |
| 关键词 | 惯性聚变能源 Inertial fusion energy 高效重频固体激光驱动器 High efficiency and high energy solid-state laser driver 甚多束阵列式激光放大模块 Multi-beam array laser amplifier 光束传输 Beam propagation 热效应 Thermal effect |
| 其他题名 | Research on Multi-beam Array Laser Amplification Technology |
| 英文摘要 | 实现惯性聚变能源技术，提供洁净能源，是激光驱动器发展的终极目标。传统激光驱动的惯性约束聚变技术及惯性聚变能源技术发展过程中存在的诸多技术难点：能量、功率、重复频率等达不到技术指标，打靶过程中的激光等离子体不稳定性难以克服等。针对当前高功率激光驱动器存在的限制，美国David Eimerl?E.等人提出StarDriver新型激光驱动器的设想，这种采用多路光束结构的设想为下一代激光驱动器的发展提供了一种新的技术路线。本文基于StarDriver新型激光驱动器的设想，创新性地提出甚多束阵列式激光放大技术，探索下一代激光驱动器中放大器的热管理与光束传输方案。 甚多束阵列式激光放大器的主要特点在于其增益介质是由多根相同的方形棒状激光增益介质阵列式排布而成，一对一地匹配阵列式光束进行传输放大。本方案结合当前高效重复频率固体激光放大器中存在的诸多技术难点针对性地提出解决方案。为提高散热能力，在方形棒状激光增益介质横向侧面之间以光胶等技术手段加入高热导率材料；为抑制寄生振荡，该高热导材料还需满足对泵浦光透射、对信号光吸收的条件；为对阵列式激光放大器实现有效的热管理，将棒上下侧面之间的间隙作为冷却液流通道；为使增益介质吸收的泵浦能量尽量均匀，提高阵列式激光放大器的输出性能，将阵列式的激光棒进行梯度掺杂。主要研究内容如下： 1、阵列式激光放大模块的设计。主要包括：增益介质选材、结构设计，泵浦结构设计，冷却循环系统设计。为保证每根增益介质棒吸收的泵浦能量较均匀，对增益介质棒的激活离子浓度进行梯度掺杂设计。为保证每束激光均能完整通过阵列式激光放大器，机械设计时确保每根增益介质棒平行且间距相等。为保证每根增益介质棒散热均匀，对冷却液体流道进行优化设计。 2、阵列式光束传输理论建模分析。在激光光学系统中，为抑制衍射效应对光束传输的影响，一般采用4f像传递系统进行光束传输。为探索阵列式光束传输与传统单光束传输的区别，分别建立了阵列式光束传输模型与同尺寸的单光束传输模型。对比分析可知阵列式光束的远场焦斑形态与传统单光束的区别很大，其形态随着阵列式光束的填充因子及相位分布而变化，远场能量集中度很差。因此，在甚多束阵列式光束传输系统中，需要探索新的空间滤波与波前补偿技术。 3、阵列式激光放大模块热效应模型的数值分析与实验验证。建立了1×11的阵列式激光放大模块热效应数值模型，从理论上对多根增益介质棒的激活离子浓度进行梯度掺杂设计。参考当前LIFE等重频固体激光驱动器的设计指标设置产热率2.7×106 W/m3，建立该梯度掺杂的阵列式激光放大模块的热效应数值模型。为验证其热效应模型，结合实际条件，设计了1×4的阵列式激光放大器，建立数值模型并进行实验，测得了其1~10Hz重频时的热波前畸变。当重频为10Hz时，平均产热率为4.6×105 W/m3，该激光头的最大热波前畸变为2.08波长 。1×4阵列式激光头的实际热效应模型与其数值模型比较吻合，初步验证阵列式激光放大模块的热效应模型与该技术方案的可行性。; The realization of inertial fusion energy technology and the provision of clean energy are the ultimate goal of laser drivers. Traditional laser-driven inertial confinement fusion technology and inertial fusion energy technology have many technical difficulties such as: substandard energy, power and repetition rate,insoluble laser plasma instability. Concerning the limitations of current high-power laser drivers, David Eimerl?E. et al. proposed the new StarDriver laser driver. This laser driver with multiple beams provide a new technical route for the next-generation laser drivers.In order to realize the idea of StarDriver laser driver,we innovatively propose a multi-beam array laser amplification technology, explore the thermal management method, and offer beam paopagation solutions for it. The main feature of the multi-beam array laser amplifier is that the gain medium is a square laser rod array, which matches the laser beam array.We provide solutions to many technical difficulties in current high efficiency, high repetition rate solid-state laser amplifiers. In order to improve the heat dissipation capability, a high thermal conductivity material is added between the lateral sides of the square laser rods. In order to suppress the parasitic oscillation, the high thermal conductivity material should have high absorption of signal light and low absorption of pump light. In order to realize effective thermal management of the amplifier, the gap between the upper and lower sides of the rods is used as coolant flow channel.In order to make thermal deposition as uniform as possible,laser rods are gradient doped. The main research content is as follows: 1.The design of multi-beam array laser amplifier mainly includes: gain medium selection, structural design, pump structure design and cooling system design. In order to ensure that the pump energy absorbed by each gain medium rod is relatively uniform, the active ion concentration of the laser rods are gradient doped. In order to ensure that each laser beam can pass through the amplifier completely, the laser rods are parallel to each other with equal intervals. In order to ensure uniform cooling of each laser rod, the cooling liquid flow path is optimized. 2. Numerical analysis of beam array propagation is showed. A 4f image-relay system which can suppress diffraction effect is generally used in laser system. In order to explore the difference between beam array propagation and single beam propagation in image-relay system, we establish numerical models of them respectively. The results show that the far-field focal spot of beam array is quite different from single beam. Its shape changes with filling factor and phase distribution of the beam array, besides, its far-field energy concentration is very poor. Therefore, a new spatial filter technology and wavefront compensation techniques need to be explored. 3. Numerical analysis and experimental verification of thermal effect of muti-beam array laser amplifier is showed. We establish a numerical model of a 1×11 beam array amplifier with heat generation power 2.7×106 W/m3, and analyse the gradient doping theory. In order to verify the numerical model of thermal effect, a 1×4 array laser amplifier is designed. In the experiment , the thermal wavefront distortion from 1 to 10 Hz is measured. When the repetition rate is 10 Hz, the average heat generation power is 4.6×105 W/m3, and the maximum thermal wavefront distortion of this laser head is 2.08 wave. The actual thermal effect model of the 1×4 array laser head is consistent with its numerical model. |
| 学科主题 | 光学工程 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31080]  |
| 专题 | 中国科学院上海光学精密机械研究所 |
| 作者单位 | 中国科学院上海光学精密机械研究所 |
| 推荐引用方式 GB/T 7714 | 陈亚林. 甚多束阵列式激光放大技术研究[D]. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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