The recent achievement of fusion ignition with laser-driven technologies at the National Ignition Facility sets a historic accomplishment in fusion energy research. This accomplishment paves the way for using laser inertial fusion as a viable approach for future energy production. Europe has a unique opportunity to empower research in this field internationally, and the scientific community is eager to engage in this journey. We propose establishing a European programme on inertial-fusion energy with the mission to demonstrate laser-driven ignition in the direct-drive scheme and to develop pathway technologies for the commercial fusion reactor. The proposed roadmap is based on four complementary axes: (i) the physics of laser–plasma interaction and burning plasmas; (ii) high-energy high repetition rate laser technology; (iii) fusion reactor technology and materials; and (iv) reinforcement of the laser fusion community by international education and training programmes. We foresee collaboration with universities, research centres and industry and establishing joint activities with the private sector involved in laser fusion. This project aims to stimulate a broad range of high-profile industrial developments in laser, plasma and radiation technologies along with the expected high-level socio-economic impact.

String instruments are complex mechanical vibrating systems, in terms of both structure and fluid–structure interaction. Here, a review study of the modeling and simulation of stringed musical instruments via the finite element method (FEM) is presented. The paper is focused on the methods capable of simulating (I) the soundboard behavior in bowed, plucked and hammered string musical instruments; (II) the assembled musical instrument box behavior in bowed and plucked instruments; (III) the fluid–structure interaction of assembled musical instruments; and (IV) the interaction of a musical instrument’s resonance box with the surrounding air. Due to the complexity and the high computational demands, a numerical model including all the parts and the full geometry of the instrument resonance box, the fluid–structure interaction and the interaction with the surrounding air has not yet been simulated.

The elastoplastic dynamic mechanical behavior of thin metallic films excited by a nanosecond laser pulse is studied. The dynamic response of the metal films is numerically described by a coupled thermal–structural, transient three-dimensional model based on the finite element method. The developed finite element model takes into account the temperature-dependent true stress–strain curves, the temperature-dependent thermal properties and matters phase changes. Since the numerical simulations include the dynamic changes of the metallic materials mechanical properties, the obtained spatiotemporal numerical solutions provide detailed descriptions of their elastoplastic response. Thus, the experimentally validated model is able to diagnose and predict spatiotemporally matters elastic and plastic deformations that occur during the interaction with a nanosecond laser pulse. Gold, copper, and aluminum thin metallic films are used as test cases to demonstrate the effectiveness of the proposed finite element modeling and simulation.

The surface photoelectric effect induced by 500 fs excimer laser pulses in a gold metallic target has been studied. Unexpectedly high current densities of 4 kA/cm², induced by laser intensities in the 3 GW/cm² range have been measured. Intense photoelectron emission could also be observed at laser intensities up to 10 GW/cm² without plasma formation. Furthermore, an electron angular distribution of 18°±2° was obtained for laser intensities in the range of 1–3 GW/cm². These results are compared to those obtained in previous work for single‐photon and multiphoton photoeffects by using longer laser pulses, and their potential exploitation for free‐electron laser and accelerator applications is discussed.

Fusion energy research is delivering impressive new results emerging from different infrastructures and industrial devices evolving rapidly from ideas to proof-of-principle demonstration and aiming at the conceptual design of reactors for the production of electricity. A major milestone has recently been announced in laser fusion by the Lawrence Livermore National Laboratory and is giving new thrust to laser-fusion energy research worldwide. Here we discuss how these circumstances strongly suggest the need for a European intermediate-energy facility dedicated to the physics and technology of laser-fusion ignition, the physics of fusion materials and advanced technologies for high-repetition-rate, high-average-power broadband lasers. We believe that the participation of the broader scientific community and the increased engagement of industry, in partnership with research and academic institutions, make most timely the construction of this infrastructure of extreme scientific attractiveness.

We present an integrated study on the scalability and performance of particle-in-cell (PIC) code simulations on CPU and GPU architectures of high parallelization focused on target normal sheath acceleration (TNSA) and laser wakefield acceleration (LWFA) experiments. The developed models follow the experimental specifications of the high-power lasers systems hosted at the infrastructures of the Institute of Plasma Physics & Lasers of the Hellenic Mediterranean University in Crete, Greece and the Extreme Light Infrastructure - Nuclear Physics in Romania. The simulations are implemented on the High-Performance Computer for Advanced Research Information System of the Greek National Infrastructures for Research and Technology. Two representative experiments for TNSA and for LWFA are initially simulated by 2D models with the minimum computational resource demands and the results are used as a reference for the scalability and performance investigation. We further extend our study to 3D models aiming to reproduce the physics involved in both laser-plasma particle accelerators. A detailed analysis of the simulation results, accompanied with the computational demands, scalability and performance of the CPU and the GPU architectures, is provided. Our research findings highlight the key features and parameters of the physical and numerical models which drive simulations to converge to reliable results by means of physics, computational and runtime demands and shed light on their influence on the efficiency and performance of the PIC simulations.