Atomic physics in ultra-dense plasmas
The question of the emissivity of hot dense matter is essential not only in the context of Inertial Confinement Fusion but also in stellar physics and planetology. The LULI has developed for more than twenty years an experimental and theoretical expertise on these research topics.
Theoretical efforts are also carried out at LULI to improve the understanding of the atomic physics of hot matter at densities higher than the density of the solid.
The impact of density on the properties of hot matter is an intense research topic, driven by the development of free electron lasers. When the density is increased and the temperature is lowered, the plasma starts to show elements characteristic of condensed matter, where short and long range forces are important. In this regime, called "strongly coupled", quantum statistics and dynamical effects have to be taken into account and the interaction between atomic physics, molecular physics and nuclear physics becomes a major problem.
What we have done at LULI :
The manifestations of induced perturbations on atoms, such as ionization potential depression (IPD) and spectral shift, are currently the subject of renewed, and sometimes controversial, discussions. A big step forward has been made thanks to the development of the ASP (Atomic-Solid-Plasma) model within the PAPD team of F. Rosmej and of the b-potential method, which has led to a very good agreement between numerical calculations and experimental data.