Time-dependent modeling of heat and gain spatial distributions of high-energy lasers

The quest for inertial fusion energy motivates the development of high-energy lasers with high repetition rates. This requires the design of solid-state amplifiers with well-controlled spatial distributions of heat load and gain. As a necessary support, a complete theoretical and numerical description of the pumping process that would include the pump illumination, its absorption by the gain medium, and the radiative and non-radiative losses is needed. In this work, we present a numerical model that takes into account the whole complex architecture of an amplifier cell to compute the time-dependent evolution of the gain and the heat spatial distributions. This method leverages the association of a ray-tracing software with a so-called “flux approach” that we have developed for modeling the amplified spontaneous emission process. We implement this model in the case of a neodymium phosphate glass 2D slab pumped with flashlamps. This hybrid method enables the analysis of complex architectures at a low computational cost which therefore allows for advanced parametric studies and optimization of solid-state laser amplifiers.