The investigation of superintense laser-driven ion sources and their potential applications offers unique opportunities for multidisciplinary research. Plasma physics can be combined with materials and nuclear science, radiation detection and advanced laser technology, leading to novel research challenges of great fundamental and applicative interest. In this paper we present interesting and comprehensive results on nanostructured low density (near-critical) foam targets for TW and PW-class lasers, obtained in the framework of the European Research Council ENSURE project. Numerical simulations and experimental activities carried out at 100 s TW and PW-class laser facilities have shown that targets consisting of a solid foil coated with a nanostructured low-density (near-critical) foam can lead to an enhancement of the ion acceleration process. This stimulated a thorough numerical investigation of superintense laser-interaction with nanostructured near-critical plasmas. Thanks to a deep understanding of the foam growth process via the pulsed laser deposition technique and to the complementary capabilities of high-power impulse magnetron sputtering, advanced multi-layer targets based on near-critical films with carefully controlled properties (e.g. density gradients over few microns length scales) can now be manufactured, with applications outreaching the field of laser-driven ion acceleration. Additionally, comprehensive numerical and theoretical work has allowed the design of dedicated experiments and a realistic table-top apparatus for laser-driven materials irradiation, ion beam analysis and neutron generation, that exploit a double-layer target to reduce the requirements for the laser system.

Laser-driven ion sources are interesting for many potential applications, from nuclear medicine to material science. A promising strategy to enhance both ion energy and number is given by Double-Layer Targets (DLTs), i.e. micrometric foils coated by a near-critical density layer. Optimization of DLT parameters for a given laser setup requires a deep and thorough understanding of the physics at play. In this work, we investigate the acceleration process with DLTs by combining analytical modeling of pulse propagation and hot electron generation together with Particle-In-Cell (PIC) simulations in two and three dimensions. Model results and predictions are confirmed by PIC simulations—which also provide numerical values to the free model parameters—and compared to experimental findings from the literature. Finally, we analytically find the optimal values for near-critical layer thickness and density as a function of laser parameters; this result should provide useful insights for the design of experiments involving DLTs.

This paper presents a laboratory-scale experimental investigation about the laser cleaning of diagnostic first mirrors from tokamak-like contaminants, made of oxidized tungsten compounds with different properties and morphology. The re-deposition of contaminants sputtered from a tokamak first wall onto first mirrors’ surfaces could dramatically decrease their reflectivity in an unacceptable way for the proper functioning of plasma diagnostic systems. The laser cleaning technique has been proposed as a solution to tackle this issue. In this work, pulsed laser deposition was exploited to produce rhodium films functional as first mirrors and to deposit onto them contaminants designed to be realistic in reproducing materials expected to be re-deposited on first mirrors in a tokamak environment. The same laser system was also used to perform laser cleaning experiments, exploiting a sample handling procedure that allows one to clean some cm2 in a few minutes. Cleaning effectiveness was evaluated in terms of specular reflectance recovery and mirror surface integrity. The effect of different laser wavelengths ( λ = 1064 , 266 nm) on the cleaning process was also addressed, as well as the impact of multiple contamination/cleaning cycles on the process outcome. A satisfactory recovery of pristine mirror reflectance (⩾90%) was obtained in the vis–NIR spectral range, avoiding at the same time mirror damaging. The results here presented show the potential of the laser cleaning technique as an attractive solution for the cleaning of diagnostic first mirrors.

This paper presents a laboratory-scale experimental investigation of laser cleaning of diagnostic First Mirrors (FMs). Redeposition of contaminants sputtered from tokamak first wall onto FMs surface could dramatically decrease their reflectivity in an unacceptable way for the functioning of the plasma diagnostic systems. Laser cleaning is a promising solution to tackle this issue. In this work, pulsed laser deposition was exploited to produce rhodium films functional as FMs and to deposit onto them carbon contaminants with tailored features, resembling those found in tokamaks. The same laser system was also used to perform laser cleaning experiments by means of a sample handling procedure that allows to clean some cm 2 in few minutes. The cleaning effectiveness was evaluated in terms of specular reflectivity recovery and mirror surface integrity. The effect of different laser wavelengths (λ = 1064, 266 nm) on the cleaning process is also addressed.

Among the existing elemental characterization techniques, particle-induced x-ray emission (PIXE) and energy-dispersive x-ray (EDX) spectroscopy are two of the most widely used in different scientific and technological fields. Here, we present the first quantitative laser-driven PIXE and laser-driven EDX experimental investigation performed at the Centro de Láseres Pulsados in Salamanca. Thanks to their potential for compactness and portability, laser-driven particle sources are very appealing for materials science applications, especially for materials analysis techniques. We demonstrate the possibility to exploit the x-ray signal produced by the co-irradiation with both electrons and protons to identify the elements in the sample. We show that, using the proton beam only, we can successfully obtain quantitative information about the sample structure through laser-driven PIXE analysis. These results pave the way toward the development of a compact and multifunctional apparatus for the elemental analysis of materials based on a laser-driven particle source.