Optimisation of Thin Plastic Foil Targets for Production of Laser-Generated Protons in the GeV Range

TL;DR

This paper combines hydrodynamic and particle-in-cell simulations to optimize thin plastic foil targets, enabling the production of laser-generated protons reaching up to 600 MeV with high-power lasers.

Contribution

It introduces a comprehensive simulation approach to optimize target conditions for high-energy proton acceleration in laser-plasma interactions.

Findings

Protons up to ~25 MeV predicted for 40 TW lasers.

Protons up to ~600 MeV predicted for 4 PW lasers.

Hydrodynamic simulations improve understanding of preplasma effects.

Abstract

In order to realistically simulate the interaction of a femtosecond laser pulse with a nanometre-thick target it is necessary to consider a target preplasma formation due to the nanosecond long amplified-spontaneous-emission pedestal and/or prepulse. The relatively long interaction time dictated that hydrodynamic simulations should be employed to predict the target particles' number density distributions prior the arrival of the main laser pulse. By using the output of the hydrodynamic simulations as input into particle-in-cell simulations, a detailed understanding of the complete laser-foil interaction is achieved. Once the laser pulse interacts with the preplasma it deposits a fraction of its energy on the target, before it is either reflected from the critical density surface or transmitted through an underdense plasma channel. A fraction of hot electrons is ejected from the target leaving the foil in a net positive potential, which in turn results in proton and heavy ion ejection. In this work protons reaching ~25 MeV are predicted for a laser of ~40 TW peak power and ~600 MeV are expected from a ~4 PW laser system.