Development of x-ray radiography for high energy density physics

Abstract

We describe an experiment performed at the LULI laser facility using an advanced radiographic technique that allowed obtaining 2D, spatially resolved images of a shocked buried-code-target. The technique is suitable for applications on Fast Ignition as well as Warm Dense Matter research. In our experiment, it allowed to show cone survival up to Mbar pressures and to measure the shock front velocity and the fluid velocity associated to the laser-generated shock. This allowed obtaining one point on the shock polar of porous carbon.

Effects of target heating on experiments usingKαandKβdiagnostics

“…The role of electron refluxing was studied in [22]. Finally Cu Kα emission was also used as a diagnostic of fast electrons in experiments using cone-guiding targets (one of the most studied variants of fast ignition) either in spherical integrated experiments with imploding targets [23], in planar experiments using cone targets [24], or in the configuration of a wire attached to a cone [25].…”

Electron acceleration at grazing incidence of a subpicosecond intense laser pulse onto a plane solid target

“…In this paper, the generation of hot electrons at grazing incidence of a subpicosecond intense laser pulse onto a plane solid target is analyzed for the parameters of the petawatt high-energy laser for heavy ion experiments (PHELIX) (Bagnoud et al, 2010;Wagner et al, 2014a) using three-dimensional (3D) particle-in-cell (PIC) modeling (Pukhov, 1999) and a wide-range hydro modeling (Povarnitsyn et al, 2012a) of the preplasma expansion under the action of the laser prepulse. Elaboration of wide-range models of the laser-matter interaction is necessary for planning and interpretation of experiments carried out in view of different applications aimed for the development of secondary sources of high energy particles and hard radiation (Morace et al, 2014;Brabetz et al, 2015;Rusby et al, 2015;Vaisseau et al, 2015). Surface acceleration and transport of energetic electrons in intense laser-matter interactions at the grazing incidence were investigated experimentally for femtosecond laser pulses of hundreds mJ energy in (Wang et al, 2013;Mao et al, 2015) and for hundred joule subpicosecond laser pulses of the laser system PHELIX in paper (Gray et al, 2011).…”

Collimated Propagation of Fast Electron Beams Accelerated by High-Contrast Laser Pulses in Highly Resistive Shocked Carbon

“…Given the longer propagation distance, this is still fairly close to the cone-tip diameter. For ∆t ≥ 3 ns the emission from the Cu tracer can no longer be distinguished from the emission of the cone tip as the distance between them, as predicted by the hydro simulation and target radiography results [33], is smaller than the ∼ 10 µm-resolution of the Cu-K α imager. The tip fluorescence yield reaches its highest value at ∆t = 3 ns due to the peak Cu-density under the shock.…”

“…The chosen ∆t were determined by a simulation of the shock formation and compression using the 2D radiative-hydrodynamic Lagrangian code chic [32], benchmarked by shock-breakout measurements on Al foils. The description of the shocked cone-targets' hydrodynamics was further benchmarked in a previous experiment by streaked optical pyrometry of the inner-cone tip and target side-on radiography using Cu K-shell ionization fluorescence as backlighter [33].…”