Target Design for XUV Probing of Radiative Shock Experiments

Radiative shocks are strong shocks characterized by plasma at a high temperature emitting an important fraction of its energy as radiation. Radiative shocks are commonly found in many astrophysical systems and are templates of radiative hydrodynamic flows, which can be studied experimentally using high-power lasers. This is not only important in the context of laboratory astrophysics but also to benchmark numerical studies. We present details on the design of experiments on radiative shocks in xenon gas performed at the kJ scale PALS laser facility. It includes technical specifications for the tube targets design and numerical studies with the 1-D radiative hydrodynamics code MULTI. Emphasis is given to the technical feasibility of an XUV imaging diagnostic with a 21 nm (~58 eV) probing beam, which allows to probe simultaneously the post-shock and the precursor region ahead of the shock. The novel design of the target together with the improved X-ray optics and XUV source allow to show both the dense post-shock structure and the precursor of the radiative shock.Comment: 12 pages, 4 figure

Counter-propagating radiative shock experiments on the Orion laser and the formation of radiative precursors

We present results from new experiments to study the dynamics of radiative shocks, reverse shocks and radiative precursors. Laser ablation of a solid piston by the Orion high-power laser at AWE Aldermaston UK was used to drive radiative shocks into a gas cell initially pressurised between $0.1$ and $1.0 \ bar with different noble gases. Shocks propagated at {80 \pm 10 \ km/s} and experienced strong radiative cooling resulting in post-shock compressions of { \times 25 \pm 2}. A combination of X-ray backlighting, optical self-emission streak imaging and interferometry (multi-frame and streak imaging) were used to simultaneously study both the shock front and the radiative precursor. These experiments present a new configuration to produce counter-propagating radiative shocks, allowing for the study of reverse shocks and providing a unique platform for numerical validation. In addition, the radiative shocks were able to expand freely into a large gas volume without being confined by the walls of the gas cell. This allows for 3-D effects of the shocks to be studied which, in principle, could lead to a more direct comparison to astrophysical phenomena. By maintaining a constant mass density between different gas fills the shocks evolved with similar hydrodynamics but the radiative precursor was found to extend significantly further in higher atomic number gases (\sim$$4$ times further in xenon than neon). Finally, 1-D and 2-D radiative-hydrodynamic simulations are presented showing good agreement with the experimental data.Comment: HEDLA 2016 conference proceeding

ELI Gammatron Beamline: A Dawn of Ultrafast Hard X-ray Science

The realization of compact X-ray sources is one of the most intriguing applications of laser-plasma based electron acceleration. These sources based on the oscillation of short micron-sized bunches of relativistic electrons provide femtosecond X-ray pulses that are collimated, bright, and partially coherent. The state-of-the-art laser plasma X-ray sources can provide photon flux of over 1011 photons/shot. The photon flux can further be enhanced with the availability of high repetition rate, high-power lasers, providing capacities complementary to the large scale facilities such as synchrotrons and X-ray free-electron lasers. Even though the optimization of such sources has been underway for the last two decades, their applications in material and biological sciences are still emerging, which entail the necessity of a user-oriented X-ray beamlines. Based on this concept, a high-power-laser-based user-oriented X-ray source is being developed at ELI Beamlines. This article reports on the ELI Gammatron beamline and presents an overview of the research accessible with the ultrashort hard X-ray pulses at the ELI Gammatron beamline

Stable electron beams from laser wakefield acceleration with few-terawatt driver using a supersonic air jet

International audienceThe generation of stable electron beams produced by the laser wakefield acceleration mechanism with a few-terawatt laser system (600 mJ, 50 fs) in a supersonic synthetic air jet is reported and the requirements necessary to build such a stable electron source are experimentally investigated in conditions near the bubble regime threshold. The resulting electron beams have stable energies of (17.4 +/- 1.1) MeV and an energy spread of (13.5 +/- 1.5) MeV (FWHM), which has been achieved by optimizing the properties of the supersonic gas jet target for the given laser system. Due to the availability of few-terawatt laser systems in many laboratories around the world these stable electron beams open possibilities for applications of this type of particle source

X-ray phase contrast imaging of biological samples using a betatron X-ray source generated in a laser wakefield accelerator

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ELI Gammatron Beamline: A Dawn of Ultrafast Hard X-ray Science

The realization of compact X-ray sources is one of the most intriguing applications of laser-plasma based electron acceleration. These sources based on the oscillation of short micron-sized bunches of relativistic electrons provide femtosecond X-ray pulses that are collimated, bright, and partially coherent. The state-of-the-art laser plasma X-ray sources can provide photon flux of over 1011 photons/shot. The photon flux can further be enhanced with the availability of high repetition rate, high-power lasers, providing capacities complementary to the large scale facilities such as synchrotrons and X-ray free-electron lasers. Even though the optimization of such sources has been underway for the last two decades, their applications in material and biological sciences are still emerging, which entail the necessity of a user-oriented X-ray beamlines. Based on this concept, a high-power-laser-based user-oriented X-ray source is being developed at ELI Beamlines. This article reports on the ELI Gammatron beamline and presents an overview of the research accessible with the ultrashort hard X-ray pulses at the ELI Gammatron beamline

Simulation of radiative shock waves in Xe of last PALS experiments

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