小尺度靶丸冲击波调控的冲击波测量技术优化及应用  

Optimization and application of shock wave measurement technology for shock-timing experiments on small-scale capsules

作　　者：杨为明[1,2] 段晓溪 张琛[1,2] 理玉龙 刘浩[1,2] 关赞洋 章欢 孙亮[1,2] 董云松 杨冬 王哲斌[1,2] 杨家敏 Yang Wei-Ming;Duan Xiao-Xi;Zhang Chen;Li Yu-Long;Liu Hao;Guan Zan-Yang;Zhang Huan;Sun Liang;Dong Yun-Song;Yang Dong;Wang Zhe-Bin;Yang Jia-Min(Research Center of Laser Fusion,China Academy of Engineering Physics,Mianyang 621900,China;National Key Laboratory of Plasma Physics,China Academy of Engineering Physics,Mianyang 621900,China)

机构地区：[1]中国工程物理研究院,激光聚变研究中心,绵阳621900 [2]中国工程物理研究院,等离子体物理全国重点实验室,绵阳621900

出　　处：《物理学报》2024年第12期267-276,共10页Acta Physica Sinica

基　　金：等离子体物理全国重点实验室基金(批准号:6142A04230101);国家自然科学基金(批准号:12074351,12275029,12205276);国防基础科研计划(批准号:JCKY2023212801)资助的课题。

摘　　要：激光聚变研究中,冲击波调控技术是实现靶丸压缩过程的熵增调谐,保证高性能内爆的关键实验技术.本文在十万焦耳激光装置上首次实现了0.375 mm半径小尺度内爆靶丸下双台阶辐射驱动的高精度冲击波调控实验测量.针对小靶丸下任意反射面速度干涉仪(VISAR)诊断有效反射区域不足的问题,通过建立的球形反射面VISAR图像光强的理论计算方法,提出了利用锁孔(keyhole)锥反射效应提升VISAR诊断空间区域的实验技术路线,使得小靶丸尺度下有效VISAR数据区域提升了近3倍.在实验中首次获得了整形内爆实验条件下低温液氘靶的冲击波测量实验数据,实现了高精度冲击波调控实验测量.实验发现,小时空尺度内爆设计条件下,由于反射冲击波的作用,激光参数的较小偏差都会对冲击波追赶后的传输行为产生显著影响,揭示了我国当前小靶丸尺度下高性能整形内爆物理过程中冲击波传输的多因素敏感性,以及冲击波调控实验对于内爆设计验证的重要性.本文提出的小靶丸冲击波调控实验技术,不仅为我国十万焦耳激光装置上整形脉冲下熵增调谐实验的开展提供了技术基础,也对基于球汇聚压缩的超高压物理研究具有重要意义.In laser fusion research,the precision of shock-timing technology is pivotal for attaining optimal adiabatic tuning during the compression phase of fusion capsules,which is crucial for ensuring the high-performance implosion.The current main technological approach for shock-timing experiments is to use keyhole targets and VISAR(velocity interferometer system for any reflector)diagnostics to measure the shock velocity history.Nonetheless,this approach encounters limitations when scaling down to smaller capsules,primarily due to the reduced effective reflection area available for VISAR diagnostics.In this work,a novel high-precision shocktiming experimental methodology is used to realize a double-step radiation-driven implosion of a 0.375 mm radius capsule on a 100 kJ laser facility.By calculating the intensity of VISAR images with spherical reflective surfaces,a new experimental technical route is proposed,i.e.using the keyhole cone reflection effect to enhance the VISAR diagnostic spatial area,which can effectively increase the effective data collection region by nearly threefold for small-scale capsules.The technique has been adeptly used to measure shock waves in cryogenic liquid-deuterium-filled capsules under shaped implosion experimental conditions,thus obtaining high-precision shock-timing experimental data.The experimental data reveal that the application of this technology can markedly enhance both the image quality and the precision of data analysis for shock wave velocity measurements in small-scale capsules.Furthermore,it is discovered that under similar laser conditions,there exist considerable variations in the shock velocity profiles.Simulation analysis shows that the difference in chasing behavior of the“N+1”reflected shock wave caused by small changes in laser intensity is the main reason for the significant difference in merging speed.It is demonstrated that small changes in laser parameters can significantly affect the transmission behavior of the shock wave.This experiment highlights the co

关 键 词：惯性约束聚变 冲击波调控 整形激光 任意反射面速度干涉仪 

分 类 号：TL632.1[核科学技术—核技术及应用]