Investigation of Light-sail and Hole-boring Radiation Pressure Accelerations upon the Interaction of Ultra-intense Laser Pulses with Thin Targets

The radiation pressure acceleration (RPA) scheme with a circularly polarized laser pulse is well-known to provide an efficient generation of intense, energetic quasi-monochromatic ion beams. Depending on the thickness of targets, the RPA appears in two distinct modes: the light-sail (LS) RPA, which develops in ultrathin targets, and the hole-boring (HB) RPA, which develops in relatively thick targets. In this work, we investigated the ion acceleration dynamics of the LS-RPA and the HB-RPA through a fully relativistic particle-in-cell (PIC) simulation. The transition and competition between LS- and HB-RPA modes are investigated with suitable explanations of a one-dimensional (1D) theoretical model. To check the validity of the 1D results and investigate the multi-dimensional effects, two-dimensional simulations are also carried out. The present work may provide a deeper understanding of RPA and useful guidelines for generating high-quality and high-fluence ion beams.