Proton Beam Generated by Multi-Lasers Interaction with Rear-Holed Target

Multi-lasers are proposed to enhance the proton acceleration in laser plasma interaction. A rear-holed target is illuminated by three lasers from different directions. The scheme is demonstrated by two-dimensional particle-in-cell simulations. The electron cloud shape is controlled well and the electron density is improved significantly. The electrons accelerated by the three lasers induce an enhanced target normal sheath acceleration (TNSA) which suppresses the proton beam divergence and improves the maximum proton energy. The maximum proton energy is 22.9 MeV, which increased significantly than that of a single-laser target interaction. Meanwhile, the average divergence angle (22.3°) is reduced. The dependence of the proton beam on the length of sidewall is investigated in detail and the optimal length is obtained. (paper)