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A significant effort has been made recently at CEL-V to improve laser facilities. OCTAL, the eight beam, 2 kJ laser, has been equipped with phosphate glass and KDP frequency tripling systems. PHEBUS, a two beam 20 kJ neodymium glass laser based on NOVA technology was denned and built and will be tested in early 1986 in close collaboration with Lawrence Livermore National Laboratory.In the field of diagnostics, the development of soft X-ray emission analysis has been emphasized.Most of the recent experimental results have been obtained at a short wave-length (0·35 μm). They deal with the effect of non-uniform illumination, 2D hydrodynamics with either plane or spherical targets, and the study of thermal transport inhibition.

ond, the short-time dynamics of all the simple fluids over remarkably large ranges of density and temperature are quantitatively described by Eq. (1) which should serve as an important benchmark for theories of the dynamics of dense fluids. Third, the phenomenon of melting has a negligible effect on the short-time dynamics-in marked contrast to the large discontinuities it causes in static properties. Fourth, the measured scattering efficiencies have confirmed recent theoretical estimates for the solid and provide insight into the mechanisms of nonlinear optical effects in simple condensed media.

The effect of laser-beam spatial modulations on plane targets is analyzed as a function of modulation scale length and target material by means of x-ray shadowgraphy. At short laser wavelength it is shown that lateral energy smoothing is clearly improved because of the strong x-ray emission from the irradiated high-Z side of layered targets. The results, interpreted in terms of radiation-driven thermal transport, are in agreement with numerical simulations. PACS numbers: 52.50.Jm, 44.40. + a, 52.25.Fi, 52.55.Mg

1.3-keV X-ray backlighting of microballoons imploded with 0.8-TW, 50-ps Nd-glass-laser pulses has been performed early during the irradiation. Transmission measurements have been interpreted in terms of fast-electron energy deposition. Targets with the thinnest walls are shown to be pre-heated up to more than 200 eV.

Microballoons filled with an equimolar deuterium-tritium mixture and coated with a plastic ablator of variable thickness are imploded by the eight-beam Octal laser (X = 1.06 jum; 0.6 TW). An X-ray r diagnostic with space-time resolution is used to analyse the implosion of the targets designed to the highest /pdr. The experimental results are compared with numerical simulations performed by a one-dimensional J Lagrangian code. A DT density of about 2 gem" 3 is obtained; the transition from an exploding-pusher regime to a more ablative one is analysed on the basis of the evolution of the preheat, the hydrodynamic efficiency and the density and temperature performance.

No abstract

Phys. 42, 1378. 3~In the two-fluid model of superfluid helium the superfluid density is identified with the square of the order parameter (see for example, Bef. 21}.We have obtained some evidence of the induced scattering of an electromagnetic wave by Compton collisions, and of its nonlinear propagation in a plasma. The interpretation of the modified spectral profile of the interacting radiation is compatible with plasma parameters.