Recent diagnostic developments at the 100 kJ-level laser facility in China

A 100 kJ-level laser facility has been designed to study inertial confinement fusion physics in China.This facility incorporates various diagnostic techniques,including optical,x-ray imaging,x-ray spectrum,and fusion product diagnostics,as well as general diagnostics assistance systems and central control and data acquisition systems.This paper describes recent developments in diagnostics at the facility.

Study of the asymmetry of hot-spot self-emission imaging of inertial confinement fusion implosion driven by high-power laser facilities

Implosion asymmetry is a crucial problem quenching ignition in the field of inertial confinement fusion.A forward-calculation method based on 1D and 2D hydrodynamic simulations has been developed to generate and study the x-ray images of hot-spot self-emission,indicating asymmetry integrated over the entire drive pulse.It is shown that the x-ray imaging photon energy should be higher to avoid the influence of the remaining shell.The contour level(percentage of the maximum emission intensity)and spatial resolution should be as low as possible,optimally less than 20%and 3μm,for characterization of higher-mode signatures such as Ps-P12 by x-ray self-emission images.On the contrary,signatures of lower-mode such as P2 remain clear at all contour levels and spatial resolutions.These key results can help determine the optimal diagnostics,laser,and target parameters for implosion experiments.Recent typical hot-spot asymmetry measurements and applications on the Shenguang 100 kJ class laser facility are also reported.

Theoretical and simulation research of hydrodynamic instabilities in inertial-confinement fusion implosions

Inertial fusion energy(IFE)has been considered a promising,nearly inexhaustible source of sustainable carbon-free power for the world's energy future.It has long been recognized that the control of hydrodynamic instabilities is of critical importance for ignition and high-gain in the inertial-confinement fusion(ICF)hot-spot ignition scheme.In this mini-review,we summarize the progress of theoretical and simulation research of hydrodynamic instabilities in the ICF central hot-spot implosion in our group over the past decade.In order to obtain sufficient understanding of the growth of hydrodynamic instabilities in ICF,we first decompose the problem into different stages according to the implosion physics processes.The decomposed essential physics processes that are associated with ICF implosions,such as Rayleigh-Taylor instability(RTI),Richtmyer-Meshkov instability(RMI),Kelvin-Helmholtz instability(KHI),convergent geometry effects,as well as perturbation feed-through are reviewed.Analytical models in planar,cylindrical,and spherical geometries have been established to study different physical aspects,including density-gradient,interface-coupling,geometry,and convergent effects.The influence of ablation in the presence of preheating on the RTI has been extensively studied by numerical simulations.The KHI considering the ablation effect has been discussed in detail for the first time.A series of single-mode ablative RTI experiments has been performed on the Shenguang-Ⅱlaser facility.The theoretical and simulation research provides us the physical insights of linear and weakly nonlinear growths,and nonlinear evolutions of the hydrodynamic instabilities in ICF implosions,which has directly supported the research of ICF ignition target design.The ICF hot-spot ignition implosion design that uses several controlling features,based on our current understanding of hydrodynamic instabilities,to address shell implosion stability,has been briefly described,several of which are novel.