Ultra-high-intensity (UHI) lasers can deliver petawatt (10^15 W) beams over ultra-short durations (from femtoseconds to picoseconds). The interaction of such a laser with a solid target allows the study of matter under extreme conditions, i.e., at solid densities brought to temperatures close to 10^7 K. These dense and hot plasmas have radiative properties (X-ray emission/absorption) that provide information about their state (temperature, etc.) and that can be measured experimentally. However, the physical mechanisms governing the heating and radiative properties are not yet fully understood.
The thesis aims to simulate the laser-target interaction using the CALDER code, a Particle-In-Cell (PIC) type code developed at the CEA. The PhD student will study the physics of isochoric heating with this code and seek to understand the predominant physical effects in these plasmas. He will model recent experiments aimed at studying these plasmas and conducted on academic laser facilities. Prospective simulations will help prepare future experiments, such as those planned on the PETAL laser at the CEA. Atomic physics codes may be used to refine the simulated X-ray spectra. The work will also include adapting CALDER to better model this physics. The results will contribute to a better understanding of the interaction between ultra-high-intensity laser-plasma and the radiative properties of irradiated solid targets.