New Scheme For Enhancement Of Maximum Proton Energy With A Cone-Hole Target Irradiated By A Short Intense Laser Pulse

Improvement of proton energy from short intense laser interaction with a new proposal of a conehole target is investigated via two-dimensional particle-in-cell simulations. The configuration of the target is a cone structure with a hole of changeable diameter through the center of the tip, with proton layers contaminated both on the target rear surface and at the rear part of the hole. In the interacting process, the cone-hole geometry enables the focus of the laser pulse by the cone structure and the consequent penetration of the intensified laser through the tip along the hole instead of reflection, which can increase the energy coupling from laser field to plasmas. The heated electrons, following the target normal sheath acceleration scheme, induce a much stronger electrostatic field in the longitudinal direction at the rear surface of the target than that in the traditional foil case. The simulation results indicate that the accelerated proton beam from the cone-hole target has a cutoff energy about 5.7 and 2.1 times larger than the foil case and the hollow cone case, respectively. Furthermore, the case of the cone-hole target without the proton layer in the hole is also analyzed to demonstrate the effect of the proton layer position and the results show that not only can the existence of the central proton layer improve the proton energy but also lead to a better collimation. The dependence of proton energy on the hole diameter and the scaling law of the maximum proton energy relative to laser intensity are also presented. Published by AIP Publishing.