Research into CUP-VISAR velocity reconstruction based on weighted DRUNet and total variation joint optimization.

This Letter proposes a CUP-VISAR data reconstruction algorithm for laser-driven inertial confinement fusion (ICF) research. The algorithm combines weighted deep residual U-Net (DRUNet) and joint optimization with total variation (TV) to improve shockwave velocity fringe image reconstruction. The simulation results demonstrate that the proposed algorithm outperforms the ADMM-TV and enhanced 3D total variation (E-3DTV) algorithms, enhancing the quality of the reconstructed images and thereby improving the accuracy of velocity field calculations. Furthermore, it addresses the challenges of the high compression ratio caused by the diagnostic requirements of the larger number of sampling frames in the CUP-VISAR system and the issues of aliasing within a large encoding aperture. The proposed algorithm demonstrates good robustness to noise, ensuring reliable reconstruction even under Gaussian noise with a relative intensity of 0.05. This algorithm contributes to ICF diagnostics in complex environmental conditions and has theoretical significance and practical application value for achieving controlled thermonuclear fusion.

Lensless computationally defined confocal incoherent imaging with a Fresnel zone plane as coded aperture.

We present a Fresnel zone plate (FZP) mask-based system for single-shot lensless confocal imaging. The system uses an FZP as coded aperture, which allows each point source to cast a unique pattern onto the sensor, representing their horizontal and axial positions. This results in a 2D sensor measurement comprising a series of FZP patterns, which records the spatial intensity distribution of the incoherent illuminant. The reconstruction process is facilitated by an algorithm based on compress sensing (CS) theory and the use of the nuclear norm of gradient scanning and hologram segmentation technology for autofocusing. The simulative and experimental results of this study align well with the expectation that every layered scene can be accurately recovered at the corresponding depth, without undesirable signals from other layers. Additionally, we analyze the deviation of the reconstruction results in the experiment, which emphasizes the need to consider the thickness of the FZP for a precise forward propagation model.

Experimental confirmation of driving pressure boosting and smoothing for hybrid-drive inertial fusion at the 100-kJ laser facility.

In laser-driven inertial confinement fusion, driving pressure boosting and smoothing are major challenges. A proposed hybrid-drive (HD) scheme can offer such ideal HD pressure performing stable implosion and nonstagnation ignition. Here we report that in the hemispherical and planar ablator targets installed in the semicylindrical hohlraum scaled down from the spherical hohlraum of the designed ignition target, under indirect-drive (ID) laser energies of ~43-50 kJ, the peak radiation temperature of 200 ± 6 eV is achieved. And using only direct-drive (DD) laser energies of 3.6-4.0 kJ at an intensity of 1.8 × 1015 W/cm2, in the hemispherical and planar targets the boosted HD pressures reach 3.8-4.0 and 3.5-3.6 times the radiation ablation pressure respectively. In all the above experiments, significant HD pressure smoothing and the important phenomenon of how a symmetric strong HD shock suppresses the asymmetric ID shock pre-compressed fuel are demonstrated. The backscattering and hot-electron energy fractions both of which are about one-third of that in the DD scheme are also measured.