PhaseX: an X-ray phase-contrast imaging simulation code for matter under extreme conditions.

We present PhaseX, a simulation code for X-ray phase-contrast imaging (XPCI), specially dedicated to the study of matter under extreme conditions (of pressure and density). Indeed, XPCI can greatly benefit the diagnosis of such states of matter. This is due to the noticeable contrast enhancement obtained thanks to the exploitation of both attenuation and phase-shift of the electromagnetic waves crossing the sample to be diagnosed. PhaseX generates synthetic images with and without phase contrast. Thanks to its modular design PhaseX can adapt to any imaging set-up and accept as inputs objects generated by hydrodynamic or particle-in-cell codes. We illustrate Phase-X capabilities by showing a few examples concerning laser-driven implosions and laser-driven shock waves.

Enhanced relativistic-electron beam collimation using two consecutive laser pulses.

The double laser pulse approach to relativistic electron beam (REB) collimation in solid targets has been investigated at the LULI-ELFIE facility. In this scheme two collinear laser pulses are focused onto a solid target with a given intensity ratio and time delay to generate REBs. The magnetic field generated by the first laser-driven REB is used to guide the REB generated by a second delayed laser pulse. We show how electron beam collimation can be controlled by properly adjusting the ratio of focus size and the delay time between the two pulses. We found that the maximum of electron beam collimation is clearly dependent on the laser focal spot size ratio and related to the magnetic field dynamics. Cu-Kα and CTR imaging diagnostics were implemented to evaluate the collimation effects on the respectively low energy (≤100 keV) and high energy (≥MeV) components of the REB.

Use of multilayer targets for achieving off-Hugoniot states.

We present an approach for the realization of extreme off-Hugoniot states of matter in laser-driven shock experiments. The method is based on the application of impedance-mismatch effect in sandwich targets. In order to verify this model we have realized numerical simulations using the two-dimensional hydrocode multi in three-layer targets (gold-aluminum-gold) with laser intensities ∼ 10(14) W/cm(2) and obtained pressures ∼ 10 Mbar. Results show the possibility of obtaining high pressures with relatively small temperatures for a low-impedance material sandwiched between layers with high density material.

Read-out of soft X-ray contact microscopy microradiographs by focused ion beam/scanning electron microscope.

A novel focused ion beam-based technique is presented for the read-out of microradiographs of Caenorhabditis elegans nematodes generated by soft x-ray contact microscopy (SXCM). In previous studies, the read-out was performed by atomic force microscopy (AFM), but in our work SXCM microradiographs were imaged by scanning ion microscopy (SIM) in a focused ion beam/scanning electron microscope (FIB/SEM). It allows an ad libitum selection of a sample region for gross morphologic to nanometric investigations, with a sequence of imaging and cutting. The FIB/SEM is less sensitive to height variation of the relief, and sectioning makes it possible to analyse the sample further. The SXCM can be coupled to SIM in a more efficient and faster way than to AFM. Scanning ion microscopy is the method of choice for the read-out of microradiographs of small multicellular organisms.