Author Affiliations
Abstract
1 National Laboratory on High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 Key Laboratory of High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
3 Shanghai Institute of Laser Plasma, China Academy of Engineering Physics, Shanghai 201800, China
The Shen-Guang II Upgrade (SG-II-U) laser facility consists of eight high-power nanosecond laser beams and one short-pulse picosecond petawatt laser. It is designed for the study of inertial confinement fusion (ICF), especially for conducting fast ignition (FI) research in China and other basic science experiments. To perform FI successfully with hohlraum targets containing a golden cone, the long-pulse beam and cylindrical hohlraum as well as the short-pulse beam and cone target alignment must satisfy tight specifications (30 and $20~\unicode[STIX]{x03BC}\text{m}$ rms for each case). To explore new ICF ignition targets with six laser entrance holes (LEHs), a rotation sensor was adapted to meet the requirements of a three-dimensional target and correct beam alignment. In this paper, the strategy for aligning the nanosecond beam based on target alignment sensor (TAS) is introduced and improved to meet requirements of the picosecond lasers and the new six LEHs hohlraum targets in the SG-II-U facility. The expected performance of the alignment system is presented, and the alignment error is also discussed.
laser drivers petawatt lasers spherical hohlraum target alignment target area High Power Laser Science and Engineering
2018, 6(1): 01000e10
Author Affiliations
Abstract
1 Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
2 Research Center of Laser Fusion, Chinese Academy of Engineering Physics, Mianyang 621900, China
3 Center for Applied Physics and Technology, Peking University, Beijing 100871, China
4 Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, Shanghai 200240, China
5 China Academy of Engineering Physics, Mianyang 621900, China
The octahedral spherical hohlraums have natural superiority in maintaining high radiation symmetry during the entire capsule implosion process in indirect drive inertial confinement fusion. While, in contrast to the cylindrical hohlraums, the narrow space between the laser beams and the spherical hohlraum wall is usually commented. In this Letter, we address this crucial issue and report our experimental work conducted on the SGIII-prototype laser facility which unambiguously demonstrates that a simple design of cylindrical laser entrance hole (LEH) can dramatically improve the laser propagation inside the spherical hohlraums. In addition, the laser beam deflection in the hohlraum is observed for the first time in the experiments. Our 2-dimensional simulation results also verify qualitatively the advantages of the spherical hohlraums with cylindrical LEHs. Our results imply the prospect of adopting the cylindrical LEHs in future spherical ignition hohlraum design.
Spherical hohlraum Laser propagation Cylindrical laser entrance hole Laser spot movement Matter and Radiation at Extremes
2016, 1(1): 2
Author Affiliations
Abstract
National Laboratory on High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800, China
With the increasing number of laser beams, the main difficulty in arranging beam guiding systems (BGSs) involves determining the corresponding relationships between the output and input ports to realize the identified light path length of all beams. Given the basic constraints of geometric arrangement, a BGS model is established, and a base-line algorithm is proposed to address the difficulty mentioned above. Boundary conditions of target area and target chamber are discussed to increase the number of laser beams, and a maximum value exists for a specific target area. Finally, the compatibility of a cylindrical hohlraum target chamber with a spherical hohlraum is analyzed, and a moveable final optics assembly is proposed to execute the switch between the two different targets.
beam guiding system laser drivers spherical hohlraum target areas Collection Of theses on high power laser and plasma physics
2015, 13(1): e12
针对间接驱动装置中球形腔结构及其光路排布，并基于光谱角色散、连续相位板(CPP)和偏振控制板联用的束匀滑方案，建立了球形腔内激光束的传输模型。由于球形腔和光路排布的高度球对称性，在对激光束经过注入孔的传输特性进行分析时，选取注入孔所在平面作为观察面，并主要对其“堵孔”问题进行分析；在对腔内的传输及腔壁的辐照特性进行分析时，选取了一系列同心球面作为观察面，以分析其均匀性。计算结果表明当不同入射角度的激光集束采用相同的CPP 设计时，随集束入射角度的增大，在注入孔处，激光的注入率降低，更易导致“堵孔”现象，但激光集束在腔内的交叉重叠会逐渐减少，其在腔壁上的光斑均匀性有所改善，且整体光斑的占空比较有所提高，更利于靶丸均匀辐照。当不同入射角度的激光集束采用不同的CPP 来优化光斑时，在注入孔的“堵孔”问题得到改善，而腔壁的占空比有所降低。在实际工作中，应综合考虑注入孔的注入率和堵孔问题、腔内的交叉、腔壁上的光斑均匀性及占空比，对球形腔中集束的入射角度进行合理设计。
激光光学 激光束特性 间接驱动 球形腔 均匀性 入射角度 中国激光
2015, 42(12): 1202006
Author Affiliations
Abstract
National Laboratory on High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800, China
With the increasing number of laser beams, the main difficulty in arranging beam guiding systems (BGSs) involves determining the corresponding relationships between the output and input ports to realize the identified light path length of all beams. Given the basic constraints of geometric arrangement, a BGS model is established, and a base-line algorithm is proposed to address the difficulty mentioned above. Boundary conditions of target area and target chamber are discussed to increase the number of laser beams, and a maximum value exists for a specific target area. Finally, the compatibility of a cylindrical hohlraum target chamber with a spherical hohlraum is analyzed, and a moveable final optics assembly is proposed to execute the switch between the two different targets.
beam guiding system laser drivers spherical hohlraum target areas High Power Laser Science and Engineering
2015, 3(1): e12
