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Recent progress in high-gain direct-drive inertial confinement fusion with the laser Megajoule is reviewed. A new baseline direct-drive target design is presented which implodes with a two-cones irradiation pattern of indirect-drive beam configuration and zooming. Perturbation amplitudes and correlated growth rates of hydrodynamic instabilities in the compressed core of a directly driven inertial confinement fusion capsule are analyzed in planar and spherical geometries, with and without heat conduction, in the unsteady state regime of the deceleration. Shock propagation in heterogeneous media is addressed in the context of first shock. The neutron and photon emissions of high-gain direct-drive target are characterized. Numerical interpretations of directly driven homothetic cryogenic D2 target implosion experiments on the Omega facility are presented.

A new solution for high-gain direct-drive fusion with the indirect drive beam irradiation of the Laser Megajoule is presented here. This solution uses 2 rings per hemisphere at polar angles of 49° and 59.5°. The 2D calculations with the hydrodynamics code FCI2 lead to a thermonuclear energy of 32 MJ with less than 1 MJ incident laser energy.

The adoption of a non-uniform dopant profile has substantially increased the tolerance to high mode deformations of our baseline indirect-drive design. In addition, a low deuterium–tritium (DT) gas density, obtained by 'dynamic quenching' at 2.3 K below triple point, could partly compensate for the decrease in robustness due to DT ageing. Finally, the net margin regarding all laser and target technological defects is about 2. As soon as a sufficient amount of laser beams and diagnostics is available, we will shoot pre-ignition experiments to tune the point design. We are studying new targets which need less energy for these campaigns.We have estimated different direct-drive schemes using indirect-drive beams. The optimal LMJ polar direct-drive configuration is a 2-cone one and leads to marginally igniting targets. A new 2-cone direct-drive scheme, associated with focal spot zooming, allows us to reach ignition with enough margin.

International audience; In a paper dated 2000 [1], a fully analytical theory of the radiative shock has been presented. This early model had been used to design [2] radiative shock experiments at the Laboratory for the Use of Intense Lasers (LULI) [3 5]. It became obvious from numerical simulations [6, 7] that this model had to be improved in order to accurately recover experiments. In this communication, we present a new theory in which the ionization rates in the unshocked (bar{Z_1}) and shocked (bar{Z_2} neq bar{Z_1}) material, respectively, are included. Associated changes in excitation energy are also taken into account. We study the influence of these effects on the compression and temperature in the shocked medium.

International audience; This paper deals with radiative shocks from both theoretical and experimental viewpoints. First, experimental results obtained at Laboratoire d'Utilisation des Lasers Intenses (LULI) at high (E˜400-800 J) energies are presented. The modeling of these phenomena is mainly performed through numerical simulations (1D and 2D calculations). We compare simulations given by several radiative hydrodynamics codes and discuss numerical methods employed. The lateral radiative looses are examined. A major point for discussion is the physical data (EOS, ionization, opacities) included in these codes. It is shown that the radiative precursor length depends on the dimensionality of codes and on the opacities employed. Additional quantities (temperature of the shock, electron density in the precursor) are also calculated and good agreement is obtained with the experimental data.