In laser-driven inertial confinement fusion, the energy coupling between laser beams and fusion target involves many complex processes at different spatial and temporal scales, such as the laser energy deposition and heat transport. On the one hand, the driver laser beams can deposit their energy into plasma via the inverse bremsstrahlung absorption (or collisional absorption) process, and then the deposited laser energy can be further transported to the high-density region of the fuel target via the electron heat conduction or X-ray radiation to drive the ablation and implosion. On the other hand, the interactions between the driver laser beams and the plasma will produce anomalous absorption processes by various parametric instabilities such as stimulated Raman scattering (SRS), stimulated Brillouin scattering (SBS), and two-plasmon decay (TPD). There parametric instabilities not only lead to substantial laser energy loss and radiation asymmetry but also generate hot electrons that may preheat the target and hence affect the compression efficiency and fusion energy gain.

In this report, we will first introduce how to simultaneously address the collisional absorption and parametric instabilities at large spatial and temporal scales, so as to obtain a more accurate and self-consistent description of the energy coupling between the driver laser and the fusion target. Subsequently, the strategies to mitigate parametric instabilities will be delineated, aiming to enhance the efficiency and quality of the energy coupling between the laser and fusion target.
 

Inertial confinement fusion,parametric instabilities,collisional absorption,stimulated Raman scattering,hot electron generation