D. Batani

Recent experiments on the hydrodynamics of laser-produced plasmas conducted at the PALS laboratory

We present a series of experimental results, and their interpretation, connected to various aspects of the hydrodynamics of laser produced plasmas. Experiments were performed using the Prague PALS iodine laser working at 0.44 μm wavelength and irradiances up to a few 10 14 W/cm 2 . By adopting large focal spots and smoothed laser beams, the lateral energy transport and lateral expansion have been avoided. Therefore we could reach a quasi one-dimensional regime for which experimental results can be more easily and properly compared to available analytical models.

A laser experiment for studying radiative shocks in astrophysics

In this article, we present a laboratory astrophysics experiment on radiative shocks and its interpretation using simple modelization.The experiment is performed with a 100-J laser ~pulse duration of about 0.5 ns! which irradiates a 1-mm 3 xenon gas-filled cell. Descriptions of both the experiment and the associated diagnostics are given. The apparition of a radiationprecursorintheunshockedmaterialisevidencedfrominterferometrydiagrams.Amodelincludingself-similar solutions and numerical ones is derived and fairly good agreements are obtained between the theoretical and the experimental results.

Simulation of preheating effects in shock wave experiments

We have analyzed the shock wave propagation experiments performed at LULI and presented at ECLIM94. The targets were aluminium foils with thickness from 5 to 25 μm. Simulations were performed with the SARA-1D multigroup radiation code. We have shown a small level of preheating caused by the absorption of X-rays with energies close to the K-edge of aluminum. Several sets of opacities were used in order to study this effect, including experimental values for cold aluminum. Simulations show a small level of visible emission induced by X-ray preheating before the arrival of the shock.

Simulations of shock generation and propagation in laser-plasmas

We analyze the results of a recent experiment performed at the PALS laboratory and concerning ablation pressure at 0.44xa0µm laser wavelength measured at irradiance up to 2xa0×xa01014xa0W/cm2. Using the code “ATLANT,” we have performed two-dimensional (2D) hydrodynamics simulations. Results show that 2D effects did not affect the experiment and also give evidence of the phenomenon of delocalized absorption of laser light.

Laser-induced forward transfer (LIFT) of material using ablation of thin films

We show the controlled transfer of thin films of different metallic materials to a receiving substrate. Single pulses from a mode locked (40 ps pulse), frequency-doubled Nd:YAG laser (energy flux ≈ 13 J/cm2 at 532 nm) were used. Receiving substrates (metals, semiconductors or crystals) were placed parallel, at a close proximity to the thin film. Optical and scanning electron microscopy (SEM) as well as EDAX analysis were performed, showing evidence of the production of micrometric scale patterns. In particular, we studied the transfer of precious metal to metal/crystals for possible application in the jewellery industry.

Time‐Resolved Analysis of High‐Power‐Laser Produced Plasma Expansion

We consider the results of an experimental investigation of the temporal evolution of plasmas produced by high power laser irradiation of various materials. The experiment was done at the LULI Laboratory (Ecole Polytechnique, Paris). A comparative analysis is presented.

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

This 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.