Collimated proton beam from an ultra-intense laser pulse irradiating parallel to the plasma interface

M Masum Haider,Zheng-Mao Sheng

doi:10.1063/5.0028014

Abstract

Recently, there has been some works on surface plasma waves excited by a laser obliquely irradiating on a thin foil target, which can cause stronger target normal sheath acceleration of protons but cannot be excited by a grazing incidence laser. Here, we demonstrate that a large amplitude Interface Plasma Wave (IPW) can be excited by a relativistic laser pulse irradiating parallel (or grazing incidence) to the interface of a solid aluminum and low density hydrogen layer. This IPW markedly enhances the sheath electric field to accelerate protons and reduce reflection of the laser pulse to improve the coupling efficiency. As a result, a collimated high energetic and lower energy spread proton beam can be efficiently achieved.

Highlights

In the early 90s of the last century, the introduction of the chirped-pulse-amplification technique to generate high power, short pulse lasers opened a new era in ion acceleration from laser–solid interactions
Et al showed that the maximum detectable proton energy varies from 0.6 MeV to 4 MeV for an aluminum foil thickness of 30 μm–0.1 μm for a laser intensity of ∼ 1019 W cm−234 whereas Liao et al reported that enhanced target normal sheath acceleration (TNSA) proton beams are successfully collected with 4 MeV–9 MeV proton energy during the interaction of an ultra-intense (6 × 1019 W cm−2) femtosecond laser pulse and a 2.5 μm aluminum target with a contaminated hydrogen layer at the rear surface.[35]
A TNSA proton acceleration of 5 MeV–9 MeV was reported for a 6 μm Al foil exposed to an ultra-intense (∼ 1020 W cm−2) laser pulse in an experimental work carried out by Ter-Avetisyan et al.[36]

Summary

INTRODUCTION

In the early 90s of the last century, the introduction of the chirped-pulse-amplification technique to generate high power, short pulse lasers opened a new era in ion acceleration from laser–solid interactions. One of the foremost accelerations of the rear surface is target normal sheath acceleration (TNSA).[10,11] Due to low experimental requirements compared with other schemes (e.g., radiation pressure acceleration and collisionless shock acceleration), TNSA is the most studied laser-induced proton acceleration mechanism.[9,12] In this mechanism, an intense ultrashort laser pulse irradiates a solid foil with hydrogen contamination or an absorbing layer on the rear. It quickly converts the foil into an overdense plasma and penetrates the skin layer, where the laser field falls off rapidly with depth.

SIMULATION PARAMETER

RESULTS

CONCLUSION