Fast electron transport and heating in solid-density matter

Two experiments have been performed to investigate heating by high-intensity laser-generated electrons, in the context of studies of the fast ignitor approach to inertial confinement fusion (ICF). A new spectrometer and layered targets have been used to detect Kα emission from aluminum heated by a fast electron beam. Results show that a temperature of about 40 eV is reached in solid density aluminum up to a depth of about 100 μm

Erratum: Refraction index of shock compressed water in the megabar pressure range

Original article: EPL, 112 (2015) 3600

Refraction index of shock compressed water in the megabar pressure range

We compressed water to megabar pressures by laser-driven shock waves and evidenced transparent, opaque and reflecting phases as pressure increases. The refraction index of water in the first two states was measured using a VISAR system. At high compression a sharp increase of the real and imaginary part of the refraction index is observed. Experiments were performed at the LULI and RAL laboratories

Erratum: Refraction index of shock compressed water in the megabar pressure range

We compressed water to megabar pressures by laser-driven shock waves and evidenced transparent, opaque and reflecting phases as pressure increases. The refraction index of water in the first two states was measured using a VISAR system. At high compression a sharp increase of the real and imaginary part of the refraction index is observed. Experiments were performed at the LULI and RAL laboratories

High density energy physics experiments on LULI 2000 facility

We present here a summary of various and preliminary experiments performed on the new facility LULI 2000. Four topics in the High Density Energy Physics have been investigated:
a– Equation of State: we studied pre-compressed water, one of most abundant component of Uranus and Neptune's mantle. We used a recent technique based on generating a shock into a diamond anvil cell pre-compressed target. Some new data on EOS surface in the range 2-3 Mbar have been obtained.
b– X-ray Thomson scattering: a strongly coupled and degenerated Aluminum plasma has been produced and probed by Ti He-alpha radiation. By using a curved spectrometer, the scattered spectrum has been measured a Compton shift from electrons has been put in evidence.
c– Astrophysics in the laboratory: A radiative supercritical shock has been produced into a gas cell filled with a low density of Xenon (0.1-0.3 bar). Various diagnostics have been implemented to determine electron density variation, precursor and shock velocities, the 2D shape of the shock at different times and electron temperature.
d– Laser accelerated flyer: different flyer plate targets have been tested. Typical shock loaded material was fused-quartz plate. Flyer velocities up to 55 km/s have been measured.

Direct Observation of strong coupling in a laser-shock compressed plasma

In this Letter we report on a near collective x-ray scattering experiment on shock-compressed targets. A highly coupled Al plasma was generated and probed by spectrally resolving an x-ray source forward scattered by the sample. A significant reduction in the intensity of the elastic scatter was observed, which we attribute to the formation of an incipient long-range order. This speculation is confirmed by x-ray scattering calculations accounting for both electron degeneracy and strong coupling effects. Measurements from rear side visible diagnostics are consistent with the plasma parameters inferred from x-ray scattering data. These results give the experimental evidence of the strongly coupled ionic dynamics in dense plasmas

Optical shadowgraphy and proton imaging as diagnostics tools for fast electron propagation in ultrahigh-intensity laser-matter interaction

International audienceThis paper reports the results of some recent experiments performed at the LULI laboratory (Palaiseau, France) concerning the propagation of large relativistic electron currents in a gas jet. We present our experimental results according to the type of diagnostics used in the experiments: (1) time resolved optical shadowgraphy and (2) proton imaging. Proton radiography images did show the presence of very strong fields in the gas probably produced by charge separation. In turn, these imply a slowing down of the fast electron cloud as it penetrates in the gas. Indeed, shadowgraphy images show a strong inhibition of propagation and a strong reduction in time of the velocity of the electron cloud from the initial value, which is of the order of a fraction of c