【作者】 周华珍；

【导师】 王世绩； 蔡希洁；

【作者基本信息】 中国工程物理研究院北京研究生部 ， 等离子体物理， 2003， 硕士

【摘要】 惯性约束核聚变不仅对辐照靶面的激光能量均衡性而且对任意时刻的功率均衡性都有很高的要求，因此功率平衡是多路激光驱动器精密化升级改造的重要环节。功率平衡作为对称性惯性约束聚变的必要条件，它是指多路激光脉冲到靶点的精确同步、能量平衡且波形一致，即瞬时功率平衡。“神光—Ⅱ”装置90％的激光能量由同轴双程主放大器提供，同时增益饱和效应产生脉冲波形畸变也主要发生在主放大器阶段，因此应用组合式角变反镜(AVM，Angular Variable Mirror)独立精密控制主放大器各路的增益性能是实现“神光—Ⅱ”装置精密化功率平衡的关键。 目前主放大器的发展主流是组合式多程放大器，因此在组合式放大器中插入AVM功率平衡新方案具有重要的应用价值。AVM实质上是大口径、高功率负载、透过率连续可调的组合式精密薄膜衰减器，通过调节AVM各单元偏转角度大小来独立控制住放大器各路的增益。 本论文在国外参考资料极其有限和国内空白的条件下，结合其他科研同志的前期预研成果，完成了AVM功率平衡新方案总体实验研究，在国际上首次实现了组合式主放大器单元增益的独立控制，并通过这种控制达到激光系统的高精度功率平衡。尽管在“神光—Ⅱ”主放大器加入AVM的工程实现难度很大，经过积极深入地展开从工程设计改进到总体实验的全面研究，在有限的实验里具体取得了以下成果： 1．系统论述和发展了功率平衡物理，为功率平衡总体实验提供了必要的理论准备；通过改进角变反镜的膜系设计要求等技术措施，基本解决了AVM新方案的安全问题，使AVM新方案总体实验成为可能。 2．获得了在线测量的大口径AVM透过率曲线精密数据，为进一步展开工作奠定了基础。考核了带有AVM主放大器在高能实验下的运行安全性，这是其可行性的前提。顺利地实现了AVM对2、4两路的200/70透过率平衡控制，并且首次完成了总体高能能量平衡实验，良好的实验结果表明了AVM调节的精密性、连续性和稳定性。首次实现了AVM对神光n输出脉冲波形的控制，获得了较好的脉冲波形畸变一致性，最终实现了多程主放大器的AVM功率平衡控制。独立负责进行了两路单台放大器系统的功率平衡实验，达到了高精度功率平衡指标，为神光n装置高精度功率平衡积累了经验。根据对功率失衡的认识和功率平衡控制的经验，认真地提出了给新建装置的功率平衡总体考虑的建议。更多还原

【Abstract】 Not only the uniformity of laser energy on the target surface, but also the high uniformity of laser intensity at any time is needed for ICF (Inertial Confinement Fusion), so power balance is the important stage of the precision upgraded modification to multi-beams high power laser driver. Power balance is necessary to ICF, including the energy balance and pulse shape uniformity at the target. 90 percent of the output energy of "SG-II" comes from its double-pass coaxial array main amplifiers, and pulse shape distortion caused by gain saturation also occurs mostly in there. Therefore precise control of gain performance of the main amplifiers by AVM(Angular Variable Mirror)is the key to the precise power balance of "SHENGUANG-II".The built-up and multi-pass amplifier is the mainstream of main amplifier nowadays, so the new scheme that is inserting the AVM in the main amplifiers has important application value. AVM is essentially a precision array film attenuator ,which has a big diameter , high power load, continuous adjustment. The gain of each beam of the main amplifiers is controlled independently by the adjusting the angle of each cell of AVM.Under the conditions of limited overseas reference, the engineering application research is studied by combining the theory research result in advance, it is in the highest flight in the world. Although it is much difficult to attain the engineering realization of AVM in "SG-II" main amplifiers, some important results have been achieved through the deep and full study of AVM which is from the its engineering design improvement to the overall experiments. The achievements are as follows:1. The AVM film coefficient was selected accurately , and made its work much appropriately;2. The precision date of the big diameter AVM transmissivity curves was gained on line,which was the necessary base of further work ;3. The security of AVM to the system was checked under the high energy experiments, which mean the preface of the feasibility of AVM ;4. The transmissivity balance between the output of Rod70 amplifiers and main amplifiers of beam 2 and 4 is controlled by the AVM successively, and the overall high energy balance was firstly done with AVM. The good results showed the precision , continuity and stability of the AVM adjustment;5. The pulse shape of "SG-II" laser was controlled triumphantly by AVM, attaining a better uniformity of multi-beam pulse shapes, and realizing the power balance control of multi-pass main amplifiers eventually ;6. 2 beams power balance experiment of single amplifier system was presided over independently by me, gaining the high precision power balance target and accumulating the experience for "SG-II" power balance ;7. According to the knowledge of power unbalance and the experience of power balance control , suggestion to the power balance of the newly built laser driver facility is seriously put forward .更多还原