Enhanced laser-driven ion acceleration from a low-density-PMMA coated metal-foil

Abstract

Strong enhancement in proton energy was investigated from a two-dimensional particle-in-cell simulation where an ultraintense laser pulse irradiates a 2-mu m thick metal foil coated with a low density, 1-mu m thick PMMA (polymethylmathacrylate - C5H8O2) on the rear surface. The reduction of PMMA density effectively increases resistivity of hot electrons, which results in the generation of a strong electrostatic field at the metal-PMMA interface in addition to the sheath electrostatic field at the PMMA-vacuum boundary. The interaction of each proton beam accelerated by the two electrostatic fields leads to the enhancement of energy for the protons originated from the PMMA-vacuum side. With a laser intensity of 1 x 10(20) W/cm(2), maximum proton energy of 80 MeV was investigated with a modulation in energy spectrum, which is 2.2 times higher than those from a metal-contamination layer target or a metal-high density PMMA target. It is also interesting that there is an energy peak around 18 MeV, which is caused by an interaction with heavier ions. (c) 2019 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).