We create hot (Te > 200 eV) and dense (Ne > 1023 cm−3) plasmas in the colliding zone of two thin foils accelerated by two laser beams of the LULI facilities. Three spectroscopic diagnostics (two 1D space-resolved spectrographs and a 2D monochromatic imaging) are used to drive the efficiency of the compression. We show that 2D effects are important. Realistic simulations of these experiments must be done, taking into account the inhomogeneity of the laser intensity in the focal spot, the foil distorsion, the plasma lateral expansion, and the lateral thermal conduction. Two-dimensional LASNEX code results are in good agreement with our experimental results. The optimized compressed plasmas generated are favorable for the exhibition of dense plasma effects due to molecular formations, and they reproduce in laboratory some astrophysical situations.

Radial inhomogeneity diagnostics in hot and dense laser plasmas are presented. By means of an analysis of the spatially resolved X-ray transverse emission of the plasma and of a theoretical modeling, we can access directly to the radial emission coefficient and to the transverse gradients. The intense aluminum Lyβ line has been chosen for this study, and different structured targets have been used to control the radiative transfer in the transverse direction. These targets (large or narrow emissive strips) give complementary results for the emission in the core (i.e., near the laser-target axis) or in the border of the plasma.