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Reducing hohlraum wall loss is one of the most important ways to improve hohlraum coupling efficiency in laser indirect drive inertial-confinement fusion. It is appeared that a high Z metallic foam as hohlraum wall material will reduce wall loss. By adjusting initial hohlraum wall density distribution along radial axes to ρ0(r)=kr, the numerical simulation results show that it can indeed bring best savings of ∼40% general wall loss. We conclude that absorbed energy mainly decreases by restraining rarefactions, and a proper slope k can optimize internal energy loss of low density and increased kinetic loss by subsonic. Also saved energy ratio reduces with source temperature decreasing. This approach would cut the reactor driver that needs quite substantially if experiments demonstrate it. [ABSTRACT FROM AUTHOR]

The first implosion tuning experiment with a shaped pulse driven was performed on the SGIII laser facility by using 2D X-ray radiography. Under the careful design, we obtained the driven symmetry both in the picket and peak. The experimental results show that the P2/P0 asymmetry can be tuned by varying the fraction energy in the inner cone both in the picket and peak. The radiation symmetry at the peak is consistent with our simulation. However, the radiation symmetry in first 0.5 ns (picket) had an unexpected negative P2/P0, which is different from the simulation; it may be caused by inner cone absorption in the tent which supported the capsule. [ABSTRACT FROM AUTHOR]

The M-band X-ray (1.6–4.4 keV) preheating and shock temperature of aluminum (Al) foil coated on a thick polystyrene (CH) layer is experimentally measured using a streaked optical pyrometer system (SOP) in the SG-III prototype laser facility for the first time. Multi-group hydrodynamic simulation captures the main characteristics of rear surface emission. Compared with the unpreheated target with bromine (Br) doped, M-band X-rays have a large impact on shock propagation inside the undoped target. Preheating changes target the initial state and generate a broader shock front, resulting in drastic variation in rear surface emission features. By comparing sensitivity analysis in the simulation and experimental uncertainty range, it is found that the SOP measurement could achieve valuable information on the shock transition time and unique emission profile, offering reliable boundary and benchmarks for simulation and analysis. Proper evaluation on the radiation source, including both the flux and the spectrum, and material opacities is essential for data interpretation. This study could promote our understanding and predictive capability required for inertial confinement fusion studies. [ABSTRACT FROM AUTHOR]

Quantitative evaluation of the fractions of high energy x-rays in a hohlraum is crucial to the indirect driven-drive scheme of inertial confinement fusion and many other applications in high energy density physics. Preheat of a sample due to x-rays sensitively depends on optical thin photons. Analyzing the motion of a sample due to preheat can thus provide valuable information of those x-rays. In this article, we propose a method to infer the temporal evolution of the x-ray fluxes in the bands of our interest. By matching the simulation results to the motions of an aluminum sample, we can infer the time-resolved x-ray fluxes around the aluminum K-edge and the gold M-band inside the hohlraum. [ABSTRACT FROM AUTHOR]