In indirect-driven laser fusion experiments,the movement of the laser absorption layer will distort the radiation uniformity on the capsule.The gold foam has advantages in symmetry control and lowering wall plasma blo...In indirect-driven laser fusion experiments,the movement of the laser absorption layer will distort the radiation uniformity on the capsule.The gold foam has advantages in symmetry control and lowering wall plasma blowoff when used in an inertial confinement fusion(ICF)hohlraum.This work investigates the motion of the laser absorption cutoff position using lowdensity foam gold walls.It is found that the motion of the laser absorption cutoff position can be significantly mitigated through optimal initial low density,tailored to a specific laser shape.For a short square laser pulse,the laser absorption cutoff position remains almost stationary at an initial density of approximately 0.6 g cm^(-3).For a long-shaped laser pulse,the minimal motion of the laser absorption cutoff position is observed at an initial density of about 0.1 g cm^(-3).This approach allows for the adjustment of the symmetry of the hohlraum radiation source.The insights gained from this study serve as a crucial reference for optimizing the hohlraum wall density.展开更多
针对从基于压缩超快成像(Compressed Ultrafast Photography,CUP)的任意反射面速度干涉仪(Velocity Interferometer System for Any Reflector,VISAR)中获得的压缩图像中重构出冲击波二维条纹图像的问题,提出一种基于卡尔曼滤波的双约...针对从基于压缩超快成像(Compressed Ultrafast Photography,CUP)的任意反射面速度干涉仪(Velocity Interferometer System for Any Reflector,VISAR)中获得的压缩图像中重构出冲击波二维条纹图像的问题,提出一种基于卡尔曼滤波的双约束图像重构算法。该算法首先基于条纹图像具有的稀疏性和平滑性,将问题转化为基于小波与全变分双先验约束的优化问题,然后,考虑到实际成像的噪声问题,采用加权卡尔曼滤波对图像已有信息进行预测和调整,最后将卡尔曼滤波引入二步迭代阈值算法的迭代过程中,进而求解该双约束优化问题,实现压缩图像的精确重构。在大噪声仿真实验中,该算法重构图像的峰值信噪比和结构相似度分别提高了4.8 dB和14.81%,显著提高了图像重构质量。在实际实验中,该算法重构出了清晰的冲击波条纹图像,且将冲击波速度最大相对误差降低了9.57%和平均相对误差降低了2.2%,验证了该算法的可行性。展开更多
基金supported by the Presidential Foundation of China Academy of Engineering Physics (No. YZJJLX 2018011)National Natural Science Foundation of China (Nos. 11775204, 11734013, 12105269 and 12004351)
文摘In indirect-driven laser fusion experiments,the movement of the laser absorption layer will distort the radiation uniformity on the capsule.The gold foam has advantages in symmetry control and lowering wall plasma blowoff when used in an inertial confinement fusion(ICF)hohlraum.This work investigates the motion of the laser absorption cutoff position using lowdensity foam gold walls.It is found that the motion of the laser absorption cutoff position can be significantly mitigated through optimal initial low density,tailored to a specific laser shape.For a short square laser pulse,the laser absorption cutoff position remains almost stationary at an initial density of approximately 0.6 g cm^(-3).For a long-shaped laser pulse,the minimal motion of the laser absorption cutoff position is observed at an initial density of about 0.1 g cm^(-3).This approach allows for the adjustment of the symmetry of the hohlraum radiation source.The insights gained from this study serve as a crucial reference for optimizing the hohlraum wall density.
文摘针对从基于压缩超快成像(Compressed Ultrafast Photography,CUP)的任意反射面速度干涉仪(Velocity Interferometer System for Any Reflector,VISAR)中获得的压缩图像中重构出冲击波二维条纹图像的问题,提出一种基于卡尔曼滤波的双约束图像重构算法。该算法首先基于条纹图像具有的稀疏性和平滑性,将问题转化为基于小波与全变分双先验约束的优化问题,然后,考虑到实际成像的噪声问题,采用加权卡尔曼滤波对图像已有信息进行预测和调整,最后将卡尔曼滤波引入二步迭代阈值算法的迭代过程中,进而求解该双约束优化问题,实现压缩图像的精确重构。在大噪声仿真实验中,该算法重构图像的峰值信噪比和结构相似度分别提高了4.8 dB和14.81%,显著提高了图像重构质量。在实际实验中,该算法重构出了清晰的冲击波条纹图像,且将冲击波速度最大相对误差降低了9.57%和平均相对误差降低了2.2%,验证了该算法的可行性。
