High Energy electron and proton acceleration by circularly polarized laser pulse from near critical density hydrogen gas target

Ashutosh Sharma

doi:10.1038/s41598-018-20506-x

Abstract

Relativistic electron rings hold the possibility of very high accelerating rates, and hopefully a relatively cheap and compact accelerator/collimator for ultrahigh energy proton source. In this work, we investigate the generation of helical shaped quasi-monoenergetic relativistic electron beam and high-energy proton beam from near critical density plasmas driven by petawatt-circularly polarized-short laser pulses. We numerically observe the efficient proton acceleration from magnetic vortex acceleration mechanism by using the three dimensional particle-in-cell simulations; proton beam with peak energy 350 MeV, charge ~10nC and conversion efficiency more than 6% (which implies 2.4 J proton beam out of the 40 J incident laser energy) is reported. We detailed the microphysics involved in the ion acceleration mechanism, which requires investigating the role of self-generated plasma electric and magnetic fields. The concept of efficient generation of quasi-monoenergetic electron and proton beam from near critical density gas targets may be verified experimentally at advanced high power – high repetition rate laser facilities e.g. ELI-ALPS. Such study should be an important step towards the development of high quality electron and proton beam.

Highlights

Ion acceleration with high-intensity lasers has attracted a great deal of attention because accelerated ion beams have extreme laminarity, ultrashort duration and high particle number in MeV energy range
In comparison to typical ion acceleration experiments which utilizes a laser-thin solid foil interaction; magnetic vortex acceleration (MVA) in near critical density (NCD) plasmas may be realized in a high density gas jet[25] which are considered to have an advantage of higher laser-plasma coupling
We focused on the aspect of efficient proton acceleration from MVA mechanism where we have used the circularly polarized (CP) laser pulse interaction with NCD plasma target

Summary

Introduction

Ion acceleration with high-intensity lasers has attracted a great deal of attention because accelerated ion beams have extreme laminarity, ultrashort duration and high particle number in MeV energy range. The use of NCD target allows the MVA mechanism to generate high-energy ions at high repetition from a high purity proton source, which is attractive for applications required high repetition rate with the solid-state lasers. MVA mechanism, employing the NCD target interaction with the linearly polarized (LP) laser pulses has been investigated theoretically[21,22,23,24] and experimentally[26,27] and attracted a great deal of attention due to its prediction for achieving sub-relativistic to relativistic electron and proton source. For the detailed review of laser-driven ion acceleration see refs[4,30]

Methods

Results

Conclusion