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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.

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Gaussian processes (GP) are widely used as a metamodel for emulating time-consuming computer codes. We focus on problems involving categorical inputs, with a potentially large number L of levels (typically several tens), partitioned in G L groups of various sizes. Parsimonious covariance functions, or kernels, can then be defined by block covariance matrices T with constant covariances between pairs of blocks and within blocks. We study the positive definiteness of such matrices to encourage their practical use. The hierarchical group/level structure, equivalent to a nested Bayesian linear model, provides a parameterization of valid block matrices T. The same model can then be used when the assumption within blocks is relaxed, giving a flexible parametric family of valid covariance matrices with constant covariances between pairs of blocks. The positive definiteness of T is equivalent to the positive definiteness of a smaller matrix of size G, obtained by averaging each block. The model is applied to a problem in nuclear waste analysis, where one of the categorical inputs is atomic number, which has more than 90 levels.

First we report two studies aimed at preparing laser integration line (LIL) experiments (LIL is the prototype of LMJ): deflection of a beam with and without ‘longitudinal’ smoothing (associated with focusing by gratings) and the radiation temperature, Tr, in a hohlraum with long pulses (10–20 ns). Experimentally, we did not see any Langmuir decay instability able to saturate the stimulated Raman scattering in a gas bag irradiated with the Omega laser. Next, in our hydro-code FCI2, we implemented an improved version of the non-LTE atomic physics model: the change in Tr in the hohlraum is negligible, but now the simulations are in agreement with experiments on x-ray conversion and on Rayleigh–Taylor instabilities (RTIs) in a spherical geometry. The RTIs in polyimide foil at 70 µm were understood, but not those at 30 µm. Finally, for the target design, we confirm the hydro-stability of the four targets of the operational domain of LMJ: the doped CH ablator of the nominal target can withstand a roughness in the range 50–100 nm. The robustness studies use 19 uncertainties coming from the laser power, the beam pointing and the target fabrication. Finally, the burning of DT has been studied in detail, identifying three regimes.