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Although the impact of the lightning electromagnetic pulse can be well approximated by using fullwave methods, generally the simulations demand a long computation time and large memory requirements, due to the number of elements that have to be included in the model of the electromagnetic environment. In this paper, we present an optimization technique to simplify the 3-D representation of the reinforcement, in case of a direct strike. By reducing the multilayered steel grid into a single-layered grid, a solution for all points in the environment can still be obtained, using less computational resources.

Quasi-static magnetic-fields up to $800\,$T are generated in the interaction of intense laser pulses ($500\,$J, $1\,$ns, $10^{17}\,$W/cm$^2$) with capacitor-coil targets of different materials. The reproducible magnetic-field peak and rise-time, consistent with the laser pulse duration, were accurately inferred from measurements with GHz-bandwidth inductor pickup coils (B-dot probes). Results from Faraday rotation of polarized optical laser light and deflectometry of energetic proton beams are consistent with the B-dot probe measurements at the early stages of the target charging, up to $t\approx 0.35\,$ns, and then are disturbed by radiation and plasma effects. The field has a dipole-like distribution over a characteristic volume of $1\,$mm$^3$, which is coherent with theoretical expectations. These results demonstrate a very efficient conversion of the laser energy into magnetic fields, thus establishing a robust laser-driven platform for reproducible, well characterized, generation of quasi-static magnetic fields at the kT-level, as well as for magnetization and accurate probing of high-energy-density samples driven by secondary powerful laser or particle beams., 16 pages, 7 figures

Commissariat a l’Energie Atomique et aux Energies Alternatives has developed the ARGOS X-ray framing camera to perform two-dimensional, high-timing resolution imaging of an imploding target on the French high-power laser facility Laser MegaJoule. The main features of this camera are: a microchannel plate gated X-ray detector, a spring-loaded CCD camera that maintains proximity focus in any orientation, and electronics packages that provide remotely-selectable high-voltages to modify the exposure-time of the camera. These components are integrated into an “air-box” that protects them from the harsh environmental conditions. A miniaturized X-ray generator is also part of the device for in situ self-testing purposes.

Interaction of high-intensity laser pulses with solid targets results in generation of large quantities of energetic electrons that are the origin of various effects such as intense x-ray emission, ion acceleration, and so on. Some of these electrons are escaping the target, leaving behind a significant positive electric charge and creating a strong electromagnetic pulse long after the end of the laser pulse. We propose here a detailed model of the target electric polarization induced by a short and intense laser pulse and an escaping electron bunch. A specially designed experiment provides direct measurements of the target polarization and the discharge current in the function of the laser energy, pulse duration, and target size. Large-scale numerical simulations describe the energetic electron generation and their emission from the target. The model, experiment, and numerical simulations demonstrate that the hot-electron ejection may continue long after the laser pulse ends, enhancing significantly the polarization charge.

In this paper we perform exploratory study of short pulses of 14 MeV neutron obtained by laser inertial confinement fusion. We focus on the neutron Radiation-Induced Conductivity (n-RIC) and we show similarities and differences with the classical RIC obtained from photon or charged particles (electron) beams. The n-RIC responses of two insulating linear polymers is experimentally compared: polyethylene (CH2)n and polytetrafluoroethylene (CF2)n.

The paper describes the preparation of the short-pulse high-energy laser PETAL that will be coupled to the French megajoule laser (LMJ) of CEA. The LMJ/PETAL facility will be opened to academic access for the international research community. In parallel diagnostics are being developed within the PETAL project and many physical problems are being addressed ranging from the study of the problems of radiation generation and activation issues to the problem of generation of large amplitude electromagnetic pulses.

We propose a model of currents induced by 14 MeV neutrons in dielectrics, which agrees well with observed data for the first time in the range of large fluxes (above 1018 n/cm2/s). We propose simple analytical model and numerical calculation using Geant4 consistent with experiments done at OMEGA Inertial Confinement Fusion facility.

In this paper we present a FDTD local space-time mesh refinement method for electromagnetic 3D simulations. The algorithm is based on the method developed which is an adaptation to FDTD of the "Adaptative Mesh Refinement" algorithm originally developed for the numerical resolution of hyperbolic conservation laws. The algorithm is only presented in 2 space dimensions with a refinement ratio of 2. Here we propose a generalisation of this method in 3 space dimensions with any refinement ratio. In the first section we explain the broad outlines of the refinement algorithm. Section 2 presents some numerical tests that we performed to check the accuracy and the stability of the method. The last section presents an application to problem of EMC in ignition laser facilities chambers.

In the field of Electromagnetic compatibility, the difficulty of the coupling of wave parasites arises on complex objects. The multiscale aspect makes impossible of modeling by only one method. Also, the purpose of this paper is to propose original solutions for several levels of coupling: structure, cable, printed circuit boards.

Results of an experiment to characterise a MeV Bremsstrahlung x-ray emission created by a short (

When high intensity (≥1019 W cm−2) laser light interacts with matter, multi-MeV electrons are produced. These electrons can be utilized to generate a MeV bremsstrahlung x-ray emission spectrum as they propagate into a high-Z solid target positioned behind the interaction area. The short duration (

The diagnostic designs for the Laser Megajoule (LMJ) will require components to operate in environments far more severe than those encountered in present facilities. This harsh environment will be induced by fluxes of neutrons, gamma rays, energetic ions, electromagnetic radiations, and, in some cases, debris and shrapnel, at levels several orders of magnitude higher than those experienced today on existing facilities. The lessons learned about the vulnerabilities of present diagnostic parts fielded mainly on OMEGA for many years, have been very useful guide for the design of future LMJ diagnostics. The present and future LMJ diagnostic designs including this vulnerability approach and their main mitigation techniques will be presented together with the main characteristics of the LMJ facility that provide for diagnostic protection.