Ion acceleration in ultra-high contrast regime

In this work, we demonstrate that the contrast of high intensity laser pulses is a key issue for many problems dealing with high-field interaction with solid-density matter. As an example, we will discuss the interaction of an Ultra-High-Contrast (UHC), Ultra-Intense, 65 fs laser pulse with an overdense plasma through the proton acceleration from ultra-thin foils (from 0.08 μm to 105 μm). The symmetric feature of the ion beams emitted from both faces of the target will be demonstrated as well as the dominant role of the p component of the electric field rather than the ponderomotive force. Simulations performed with a 2D particle-in-cell code are in close agreement with all experimental data. UHC experiments prove to be a good as benchmarks for theories and models.