PPPS-2013: New fast and accurate numerical method for laser-produced relativistic electrons beams transport in the context of ICF — Applications to fast and shock ignition

Abstract

Summary form only given. One major issue to address in Inertial Confinement Fusion (ICF) is the detailed description of the kinetic transport of laser generated fast electrons in the time and space scales of the hydrodynamic evolution of the imploded target. We have developed, at CELIA, a fast reduced kinetic model for relativistic electrons transport based on the angular moments of the relativistic Fokker-Planck equation, the M1 model1. This model takes into account the slowing down of fast electrons through collisions with plasma electrons (free and bounded), plasmons and the elastic scattering of fast electrons on plasma ions and electrons. The self-consistent magnetic and electric fields are computed thanks to a generalized Ohm law. This module has been implemented into the 2D radiation hydrodynamic code CHIC2. The M1 model is used as well as for the Fast Ignition (FI) than for the Shock Ignition (SI) schemes. A recent experiment of relativistic electrons transport through Aluminum foils is analyzed thanks to this multi-scales tool. Because of its computing speed, various initial configurations have been tested to reproduce experimental data. In addition, due to its structure, the effects of electric and magnetic fields can easily be highlighted and so the resistive fast electrons losses are directly compared to the collisional losses. Concerning Shock Ignition scheme, it is shown that the energy transfer by fast electrons from the corona to the compressed shell is a important mechanism in the creation of ablation pressure. A 30 keV energy electron beam of 2 - 5 PW/cm2 energy flux may create a pressure amplitude of more than 300 Mbar within few tens of ps in a precompressed solid material3. The dynamics of the ablation layer and the shock evolution are also presented in realistic configurations.