Bernhard Zielbauer

Optical generation of energetic particle bunches requires high-power laser facilities operating in picosecond or femtosecond temporal domain. It is therefore preferable to use also short laser pulses in all-optical platforms providing quasistationary electromagnetic fields for guiding and focusing of such particle beams, increasing their brightness and decreasing their angular divergence. In this work, theoretical and experimental results are discussed for a novel electromagnetic guiding setup based on a shaped spiral-like "snail" target with a relatively large focusing aperture in comparison with the previous studies. Due to the diameter increased to a submillimeter scale, wider particle bunches may be efficiently focused, as shown with theoretical modeling using the field distributions, consistent with the presented experimental data.

We report on commissioning experiments at the high-energy, high-temperature (HHT) target area at the GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany, combining for the first time intense pulses of heavy ions from the SIS18 synchrotron with high-energy laser pulses from the PHELIX laser facility. We demonstrate the use of X-ray diagnostic techniques based on intense laser-driven X-ray sources, which will allow probing of large samples volumetrically heated by the intense heavy-ion beams. A new target chamber as well as optical diagnostics for ion-beam characterization and fast pyrometric temperature measurements complement the experimental capabilities. This platform is designed for experiments at the future Facility for Antiproton and Ion Research in Europe GmbH (FAIR), where unprecedented ion-beam intensities will enable the generation of millimeter-sized samples under high-energy-density conditions.

A new high energy proton radiography facility PRIOR-II (Proton Microscope for FAIR) has been designed, constructed, and successfully commissioned at the GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany) pushing the technical boundaries of charged particle radiography with normal conducting magnets to the limits. The setup is foreseen to become a new and powerful user facility for carrying out fundamental science experiments in the fields of plasma and shock wave physics, material science, and medical physics. It will help address several unsolved scientific challenges, which require high-speed and precise non-invasive diagnostic methods capable of probing matter with up to 100 g/cm2 areal density. PRIOR-II is specifically designed to utilize the full timing capabilities of the SIS-18 synchrotron at GSI for ultra-fast dynamic experiments with up to 4 GeV protons and will also be fielded at the future FAIR facility, where higher proton energies and beam intensities will be available. This will enable experiment geometries with even higher areal densities, more flexible experiment timing, and further enhanced spatial resolution.

Single-shot X-ray phase-contrast imaging is used to take high-resolution images of laser-driven strong shock waves. Employing a two-grating Talbot interferometer, we successfully acquire standard absorption, differential phase-contrast, and dark-field images of the shocked target. Good agreement is demonstrated between experimental data and the results of two-dimensional radiation hydrodynamics simulations of the laser–plasma interaction. The main sources of image noise are identified through a thorough assessment of the interferometer’s performance. The acquired images demonstrate that grating-based phase-contrast imaging is a powerful diagnostic tool for high-energy-density science. In addition, we make a novel attempt at using the dark-field image as a signal modality of Talbot interferometry to identify the microstructure of a foam target.

We present in situ measurements of spectrally resolved X-ray scattering and X-ray diffraction from monocrystalline diamond samples heated with an intense pulse of heavy ions. In this way, we determine the samples’ heating dynamics and their microscopic and macroscopic structural integrity over a timespan of several microseconds. Connecting the ratio of elastic to inelastic scattering with state-of-the-art density functional theory molecular dynamics simulations allows the inference of average temperatures around 1300 K, in agreement with predictions from stopping power calculations. The simultaneous diffraction measurements show no hints of any volumetric graphitization of the material, but do indicate the onset of fracture in the diamond sample. Our experiments pave the way for future studies at the Facility for Antiproton and Ion Research, where a substantially increased intensity of the heavy ion beam will be available.

We have recently proposed a new technique of plasma tailoring by laser-driven hydrodynamic shockwaves generated on both sides of a gas jet [Marquès et al., Phys. Plasmas 28, 023103 (2021)]. In a continuation of this numerical work, we study experimentally the influence of the tailoring on proton acceleration driven by a high-intensity picosecond laser in three cases: without tailoring, by tailoring only the entrance side of the picosecond laser, and by tailoring both sides of the gas jet. Without tailoring, the acceleration is transverse to the laser axis, with a low-energy exponential spectrum, produced by Coulomb explosion. When the front side of the gas jet is tailored, a forward acceleration appears, which is significantly enhanced when both the front and back sides of the plasma are tailored. This forward acceleration produces higher-energy protons, with a peaked spectrum, and is in good agreement with the mechanism of collisionless shock acceleration (CSA). The spatiotemporal evolution of the plasma profile is characterized by optical shadowgraphy of a probe beam. The refraction and absorption of this beam are simulated by post-processing 3D hydrodynamic simulations of the plasma tailoring. Comparison with the experimental results allows estimation of the thickness and near-critical density of the plasma slab produced by tailoring both sides of the gas jet. These parameters are in good agreement with those required for CSA.

This article was originally published online on 21 July 2023 with typesetting errors. These errors have been corrected. AIP Publishing apologizes for the errors

Laser-driven x-ray backlighting can be used to image fast dynamic processes like the propagation of laser-driven shock waves in matter. We demonstrate and evaluate the feasibility of operating the JUNGFRAU detector designed by PSI, a direct detecting x-ray detector, in environments with extreme electromagnetic pulses. The electromagnetic pulse-protective housing is specifically designed for this detector and optimized for pump-probe experiments at the Petawatt High-Energy Laser for Heavy Ion EXperiments (PHELIX) facility at the GSI Helmholtzzentrum für Schwerionenforschung GmbH. The beryllium x-ray entrance window of the protective housing has a high x-ray transmission of 94% at 8 keV. Measurements have shown that the housing simultaneously provides a relative damping of the electromagnetic field on average higher than 1000 in the frequency range of 100 MHz to 5 GHz. The results demonstrate the feasibility of operating digital detectors in experiments where strong electromagnetic pulses are present.

In this paper we report the perspectives of the development of the XUV laser sources and applications using High-power laser facilities. We focus our paper on the present status of the French LASERIX facility and more especially about its role in the development of the XUV laser sources considering the French "Institut de la Lumière Extrême " (ILE) and the potential European project Extreme Light Infrastructure (ELI). Finally, we present the scientific perspectives of X-ray laser sources developments using these laser facilities.