[en] One of source term of Z-Pinch experiments is the gas puff density profile. In order to characterize the gas jet, an experiment based on interferometry has been performed. The first study was a point measurement (a section density profile) which led us to develop a global and instantaneous interferometry imaging method. In order to optimise the nozzle, we simulated the experiment with a flow calculation code (ARES). In this paper, the experimental results are compared with simulations. The different gas properties (He, Ne, Ar) and the flow duration lead us to take care, on the one hand, of the gas viscosity, and on the other, of modifying the code for an instationary flow

[en] We present some plate impact experiments on a commercial grade of graphite. The dynamic loadings range between 0.3 and 14 GPa under shock, and reach 23 GPa under reshock in the samples, which were approximately 20% porous and macroscopically isotropic. Material velocity at the sample rear surface is measured and recorded optically with Visar or Perrot-Fabry interferometers. These experimental results are then compared to hydrodynamic simulations, where we use a model that takes porosity into account. Our model is also compared to previously published experimental data. The overall agreement is good.

[en] For many years, spall fracture of shock-loaded materials has been one of the most widely studied phenomena in shock physics, for both fundamental and technological motivations. Laser driven shocks provide a means to investigate this process over ranges of extremely high strain rates and short durations, and they allow recovering spalled samples more easily than plate impact or explosive loading techniques. In this paper, we present laser shock experiments on gold and aluminium in cryogenic conditions (relevant in the context of inertial confinement fusion), and on iron at high temperatures up to about 1000 K. Time-resolved measurements of the free surface velocity are used to determine the evolution of the spall strength with sample temperature. They are complemented by post-test observations of the recovered targets, which reveal clear changes in fracture surface morphology in the spall craters. In the case of iron, possible influences of pressure-induced phase transformations prior to tensile loading are discussed on the basis of hydrodynamic simulations

[en] Interaction of a laser beam with a target may generate a high velocity expanding plasma plume, solid debris, and liquid nano- and microparticles. They can be produced from plasma recombination, vapor condensation or by a direct expulsion of the heated liquid phase. Two distinct sizes of particles are observed depending on the temperature achieved in the plasma plume: Micrometer-size fragments for temperatures lower than the critical temperature, and nanometer-size particles for higher temperatures. The paper presents experimental observations of fragments and nanoparticles in plasma plumes created from gold targets. These results are compared with theoretical models of vapor condensation and microparticle formation

[en] With the development of high energy laser facilities dedicated to inertial confinement fusion, the question of debris ejection from metallic shells subjected to intense laser irradiation has become a key issue. We have used two diagnostics to investigate fragmentation processes. Recovery of ejected fragments has been performed in a highly transparent gel of density 0.9 g/cm³. Fragments sizes, shapes, and penetration depths, can be easily observed with a spatial resolution of micrometer-order. Complementary data are provided by transverse shadowgraphy which allows to obtain quasi-instantaneous, successive pictures of the debris clouds and mean ejection velocities.

[en] The debris and shrapnel generated by laser targets will play an increasingly major role in the operation of large laser facilities such as NIF, LMJ, and Orion. Past experience has shown that it is possible for such target debris/shrapnel to render diagnostics inoperable and also to penetrate or damage optical protection (debris) shields. We are developing the tools to evaluate target configurations, in order to better mitigate the generation and impact of debris/shrapnel, including development of dedicated modelling codes. In order to validate these predictive simulations, we briefly describe a series of experiments aimed at determining the amount of debris and/or shrapnel produced in controlled situations. We use glass plates and aerogel to capture generated debris/shrapnel. The experimental targets include hohlraums, halfraums, and thin foils in a variety of geometries. Post-shot analysis includes scanning electron microscopy and x-ray tomography. We show results from a few of these experiments and discuss related modelling efforts

[en] We present an overview of recent experiments fielded on the LIL facility. A key issue for mega-joule class laser facilities is shrapnel fragment generation. A specific collector was therefore developed to capture debris in aerogel and dedicated shots were done to quantitatively evaluate target fragmentation phenomena. The LIL panel of transmitted and backscattered light diagnostics is well suited for laser-plasma interaction (LPI) experiments. This include gas-filled hohlraum configurations relevant to Indirect Drive ignition targets in order to test the specific LMJ longitudinal SSD technique, as well as LPI experiments with foam targets for laser beam smoothing in underdense plasma in the context of Direct Drive. After Visar commissioning a campaign was dedicated to boron Equation of State (EOS).

[en] The generation of neutron/gamma radiation, electromagnetic pulses (EMP), debris and shrapnel at mega-Joule class laser facilities (NIF and LMJ) impacts experiments conducted at these facilities. The complex 3D numerical codes used to assess these impacts range from an established code that required minor modifications (MCNP - calculates neutron and gamma radiation levels in complex geometries), through a code that required significant modifications to treat new phenomena (EMSolve - calculates EMP from electrons escaping from laser targets), to a new code, ALE-AMR, that is being developed through a joint collaboration between LLNL, CEA, and UC (UCSD, UCLA, and LBL) for debris and shrapnel modelling.