High-quality GeV proton beam generation from multiple-laser interaction with double-layer target

Abstract

A scheme for significantly enhancing the beam quality of laser-driven proton acceleration is proposed and investigated with particle-in-cell simulation: two linearly polarized Gaussian laser pulses obliquely irradiate a double-layer target that acquires a periodic surface structure that reduces the reflection, improves the focusing, and enhances the energy coupling of the third, or main, laser pulse that follows. The oblique pulses also provide some initial kinetic energy to the initially static target electrons and thus protons, which is very crucial for efficient acceleration. As a result, a proton beam of 1.15 GeV peak energy, very low energy spread ∼4%, and small divergence angle ∼5° can be obtained with laser intensities of 1021 W cm−2, which is significantly lower than that of the other recently proposed schemes.