Section: Overall Objectives

Overall Objectives

Controlled fusion is one of the major challenges of the 21st century that can answer the need for a long term source of energy that does not accumulate wastes and is safe. The nuclear fusion reaction is based on the fusion of atoms like atoms of deuterium and tritium. This reaction does not produce long-term radioactive wastes, unlike today’s nuclear power plants which are based on nuclear fission.

In order either to achieve a sustained fusion reaction or simply to obtain a positive energy balance, it is necessary to confine sufficiently the plasma for a long enough time. This is one of the main issue in the ability to produce energy from fusion reaction. If the confinement density is higher, the confinement time can be shorter but the product of both quantities needs to exceed some threshold values.

Two major research approaches are currently followed towards the objective of fusion based nuclear plants and both of them will be considered in the present project KALIFFE :

• Magnetic Fusion (ITER Program in Cadarache). The idea behind magnetic fusion is to use large toroidal devices called tokamaks in which the plasma can be confined thanks to large applied magnetic field. The international project ITER is based on this idea and aims to build a new tokamak which could demonstrate the feasibility of the concept.

• Inertial Confinement Fusion (ICF - Laser Méga-Joules in Bordeaux). The inertial fusion concept consists in using intense laser beams or particle beams to confine a small target containing the deuterium and tritium atoms. For instance, the Laser Mégajoule which is being built at CEA in Bordeaux will be used for experiments using this approach

Both approaches lead to study hot plasmas, which constitute an important field in physics and applied mathematics, spanning many different length and time scales. Accurately simulating hot plasmas requires solving the physics of hydrodynamics, radiation and electron transport, wave-wave interactions, wave-particle interactions and particle-particle interactions, to name a few processes.

Performing such a calculation that solves such physics at all these length and time scales remains computationally unfeasible even with an exa-scale capability. Thus, it is important to differentiate between the physics that must be fully solved, and the physics that can be included with a reduced model description in a fully integrated simulation.

This project is intended to be focused on the fundamental computational challenges that arise when simulating high energy plasmas. This includes aspects of five and six-dimensional formulations of plasma transport theory, plasma-waves interactions, and the design of robust analytic techniques for software verification. These are all "multi-physics" problems, involving electromagnetic interactions, turbulent fluid behavior, and collisions. These problems are also "multiscale", requiring multi-resolution and hybrid algorithms coupling the different scales. Therefore, different numerical methods for the simulation of the governing integro-differential equations that scale with problem size and are suitable for high-performance computing will be developed. This work in modeling and numerical simulation of plasmas will be applied to problems like fast ignitor concept in the laser fusion research. Another application is devoted to the development of Vlasov codes in a toroidal configuration in the framework of the magnetic fusion program in collaboration with several Inria projects.