Theoretical Study of Laser Energy Absorption Towards Energetic Proton and Electron Sources
Résumé
Our main goal is to describe and model the energy transfer from laser to particles, from the transparent to less transparent regime of laser-plasma interaction in the ultra-high intensity regime, and using the results obtained to optimize laser ion acceleration. We investigate the case of an ultra high intensity (10²² W/cm²) ultra short (20 fs) laser pulse interacting with a near-critical density plasma made of electrons and protons of density 5 n_{c} (where n_{c} = 1.1·10²¹ cm⁻³ is the critical density for a laser wavelength of 1 µm). Through 2D particle-in-cell (PIC) simulations, we study the optimal target thickness for the maximum conversion efficiency of the laser energy to particles. Theoretical modelling of the predominant laser-plasma interaction mechanisms predicts the particle energy and conversion efficiency optimization. Our studies led to an optimization of the target thickness for maximizing electron and proton acceleration.