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The SEPAGE spectrometer (Spectrometre Electrons Protons A Grandes Energies) was realized within the PETAL+ project funded by the French ANR (French National Agency for Research). This plasma diagnostic, installed on the LMJ-PETAL laser facility, is dedicated to the measurement of charged particle energy spectra generated by experiments using PETAL (PETawatt Aquitaine Laser). SEPAGE is inserted inside the 10-meter diameter LMJ experimental chamber with a SID (Diagnostic Insertion System) in order to be close enough to the target. It is composed of two Thomson Parabola measuring ion spectra and more particularly proton spectra ranging from 0.1 to 20 MeV and from 8 to 200 MeV for the low and high energy channels respectively. The electron spectrum is also measured with an energy range between 0.1 and 150 MeV. The front part of the diagnostic carries a film stack that can be placed as close as 100 mm from the target center chamber. This stack allows a spatial and spectral characterization of the entire proton beam. It can also be used to realize proton radiographies.

In recent years, shock waves driven by high power lasers have become a reliable tool for the study of the equation of state (EOS) of material sin the Megabar pressure range, where they become strongly correlated, degenerate, dense plasmas. The EOS of water at very high pressures plays a very important role in astrophysics. In particular, the large magnetic field measured on Uranus and Neptune by Voyager 2 is assumed to be generated in the 'ice' layers where pressures up to 6 Mbar are reached. Recent calculations predict an insulator-metallic phase transition of water in this regime. Here, we present some preliminary results form a recent experiment on water EOS performed with the laser PHEBUS and funded by the European Union in the framework of the 'Access to Large Scale Facilities' program. In the experiment, structured targets made of an Aluminium step followed by a water layer are irradiated by the laser at an intensity approximately equals 4.1014 W.cm-2 to generate a shock wave. Velocities are measured in the two materials using a VISAR interferometric diagnostic for water, and a streak camera to measure target emission for Al. EOS points for water are obtained with the impedance mismatch method using Al EOS as a reference. Water reflectivity was also measured.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Experiments were performed in indirect drive at the Phebus laser facility to study the ablation front Rayleigh-Taylor instability. Brominated plastic targets with sinusoidal modulations were accelerated with a temporally shaped soft x-ray pulse created in a hohlraum. The growth of the perturbations was observed by face-on radiography using a new Wolter-like microscope and the acceleration was derived from separate side-on velocity measurements.

A toroidal crystal spectrometer was designed with the purpose of measuring the aluminum K-absorption edge shift, in the wavelength range around 7.9 angstroms, in highly compressed matter. The expected shift is about 100 mA (approximately 20 eV). The x-ray reflected from the crystal are focused onto a streak camera slit of 16 mm high and 100 micrometers width, to obtain a time resolved spectrum. High resolution value and dispersion of about 1 angstrom/16 mm on the detection window is hence required. A crystal with a toroidal surface is used to enhance the focusing power in the spatial dimension as in the spectral one. Numerical simulations are performed by means of 1D and 2D codes for the determination of the crystal characteristics like the dimension and the curvature radius with respect to the geometric constraints. Some results will be presented concerning the obtained spectra.