Laser-driven ion acceleration (LDIA) presents a compact and cost-effective alternative to traditional particle accelerators. Recent developments have enabled proton energies up to 160 MeV using ultra-thin foil targets irradiated by ultra-intense laser pulses, exploiting relativistic transparency regimes. This regime occurs when the laser pulse penetrates a near-critical plasma, generated by tailoring target thickness to the laser parameters, enabling multi-stage acceleration and enhancing proton energies without the need for contrast-enhancing techniques like plasma mirrors. This PhD project aims to further optimize proton acceleration in the transparency regime, with the goal of achieving 200 MeV energies using high-repetition-rate laser systems.

The first phase involves 3D Particle-In-Cell (PIC) simulations with Smilei, focusing on the sensitivity of laser-target interaction to temporal laser profiles for robust acceleration. The second phase investigates cryogenic hydrogen ribbon targets, developed by CEA, as an alternative to solid foils. These targets are near-critical in density, tunable in thickness, and compatible with high-repetition-rate operation, while providing mono-species proton beams. Experimental work will be conducted in collaboration with LULI and CEA, with preparations for experiments at the Apollon facility.