[en] The nominal configuration of inertial confinement fusion with the Laser Megajoule (LMJ) uses a cylindrical hohlraum with two polar holes for the entrance of 60 laser quads. But the LMJ facility makes it possible to use a spherical hohlraum with more than two holes. We have studied two alternate configurations, in which 56 and 44 laser quads enter a spherical hohlraum through four and six holes respectively, with the same wall surface as in the nominal cylindrical hohlraum. We have estimated the intrinsic and random radiation asymmetries on the nominal capsule A1040 in these two configurations. (authors)

[en] In order to examine if the reaction rates uncertainties could account for the discrepancy between theoretical predictions and observations, the authors performed independent calulations of the abundances of these elements in the frame of the hot Standard Big-Bang. In this contribution, the authors also took into account the uncertainties on the nuclear reaction rates involved in these computations. (Auth.)

[en] The destruction rates of lithium, beryllium and boron inside a 1 solar mass star are calculated using the nuclear reaction rates recently updated. The isotopic and elemental composition of the material ejected by the star inside the interstellar medium at the end of its life is determined, in order to evaluate its influence on the galactic evolution of the ratios ⁷Li/⁶Li, ¹¹B/¹⁰B and Li/B

[en] The Laser Megajoule (LMJ) facility is under construction and will deliver up to 2 MJ of 0.35 μm light in 240 beams. Four similar beams are now available on the Ligne d'Integration Laser (LIL) facility, and the first LIL plasma experiments were completed this winter. On this paper, we will focus on LMJ design studies in indirect-drive configuration. Different capsules with CH(Ge) ablator are studied. Laser plasma instabilities will be smaller in 250 eV targets whereas 350 eV capsules will be more tolerant to initial roughness. A global model enables us to minimize these risks inside possible laser domain. Our nominal design A1040 has similar margins regarding these two uncertainties. LMJ ignition studies aim to quantify more precisely these risks with specific codes and experiments on Omega and LIL facilities. 2D-hydrodynamic instability simulations were performed with different CH and DT roughness. Sensitivity of hydro instability growth to DT gas density, which depends on the cryogenic temperature, is evaluated with a 1D-mixed model. The same target, with graded dopant instead of uniform one, is less sensitive to ablator roughness. Low mode deformations of the DT shell are estimated at maximum velocity. The main causes of deformation are CH thickness defects for modes 1-2 and intrinsic X-ray non-uniformities for modes 4-10. Effects of random errors as laser mis pointing, imbalance and hohlraum geometrical defects are fewer, according to LMJ specifications. Intrinsic and random radiation asymmetry due to a tetraedrical hohlraum compatible with direct-drive configuration (beams at angles of 49 degree centigree from the vertical shifted at 78 degree centigree) has been estimated. The comparison of second and third harmonic light potentialities is in progress. (Author)

[en] Numerical studies show that a rugby-shaped hohlraum for indirect drive laser ignition has some advantages: it allows a better symmetry for the X-ray irradiation of the central target and it required less laser power. Rugby-shaped cavities have been tested successfully at the Omega facility. The energetic advantage is all the more important as the cavity is bigger. Simulations have shown that a rugby-shaped hohlraum plus adequate materials for the intern wall plus an optimization of the central target could open the way to an ignition with only 160 laser beams at the LMJ (Megajoule Laser) facility. (A.C.)

[en] Our study is in line with the robustness of the LMJ target and the definition of safety margins. It is based on the determination of the 'acceptable gain', defined as 75% of the nominal gain. We have tested the sensitivity of the gain to physical and numerical parameters in the case of deteriorated implosions, i.e. when implosion conditions are not optimized. Moreover, we have simplified the radiative transport model, which enabled us to save a lot of computing time. All our calculations were done with the Lagrangian code FCI2 in a very simplified configuration. (authors)

[en] Globular clusters provide information on the early evolution of the Galaxy. Correlations between kinematics and composition might allow us to probe the most active period of Galactic Chemo-Dynamics (GCD). If the sub-class of low metallicity globulars traces the star formation history of the halo, we can use them to investigate the chemical evolution of the collapsing proto-galaxy. The absence of an observed radial metallicity gradient presents a constraint on collapse models. Following cluster orbits during collapse, when the potential changes rapidly, and in a static potential thereafter, we find only a small present-day metallicity gradient. Therefore, the absence of a pronounced metallicity gradient is not a strong argument against ELS scenarios of halo formation

[en] A novel rugby-ball shaped hohlraum is designed in the context of the indirect-drive scheme of inertial-confinement fusion (ICF). Experiments were performed on the OMEGA laser and are the first use of rugby hohlraums for ICF studies. Analysis of experimental data shows that the hohlraum energetics is well understood. We show that the rugby-ball shape exhibits advantages over cylinder, in terms of temperature and of symmetry control of the capsule implosion. Simulations indicate that rugby hohlraum driven targets may be candidates for ignition in a context of early Laser MegaJoule experiments with reduced laser energy

[en] A model is presented to evaluate the variation with depth of Cosmic Ray particle fluxes as they propagate inside spherical solid bodies. This model is used to calculate the production rates of spallogenic nuclei inside spherical meteorites of various sizes and compositions and the resulting abundances are compared to rare gases data in the iron meteorite Grant. It is shown that a preatmospheric map of the meteorite's slice used for measurements can be established if a more refined modelization of the secondary particles production is used and if more precise data along various radii of the meteorite become available

[en] The LMJ experimental plans include the attempt of ignition and burn of an ICF capsule with 40 laser quads, delivering up to 1.4MJ and 380TW. New targets needing reduced laser energy with only a small decrease in robustness are then designed for this purpose. A first strategy is to use scaled-down cylindrical hohlraums and capsules, taking advantage of our better understanding of the problem, set on theoretical modelling, simulations and experiments. Another strategy is to work specifically on the coupling efficiency parameter, i.e. the ratio of the energy absorbed by the capsule to the laser energy, which is with parametric instabilities a crucial drawback of indirect drive. An alternative design is proposed, made up of the nominal 60 quads capsule, named A1040, in a rugby-shaped hohlraum. Robustness evaluations of these different targets are in progress