The objective of this internship is to study by digital simulation different optical smoothing configurations achievable on the LMJ in order to optimize the current smoothing. During the internship the candidate will become familiar with the different optical smoothing techniques and the phenomena of parametric instabilities involved in laser/plasma interaction. Then he/she will seek, through hydrodynamic simulations, to improve the propagation of a laser beam by optimizing the optical smoothing parameters. The internship will be organized as follows: Bibliographic study through theses and scientific articles (in English) in order to discover the context of laser/plasma interaction. Getting started with digital tools (Linux, supercomputer, code, code chaining, diagnosis) on 2D and possibly 3D cases. Numerical studies of different smoothings. writing an internship thesis (continuously during the internship). In accordance with the commitments made by the CEA in favor of the integration of people with disabilities, this job is open to everyone. Participating in national protection, an administrative investigation is carried out for all CEA employees in order to ensure the integrity and security of the nation.