On very short and intense laser-plasma interactions

TL;DR

This paper investigates the effects of very short, intense laser pulses on low-density plasmas, modeling electron acceleration and phenomena like wakefields and the slingshot effect using simplified Hamiltonian systems.

Contribution

It introduces a simplified MFD model to describe laser-plasma interactions and predicts the wakefield and slingshot electron expulsion phenomena.

Findings

Electrons can be accelerated to relativistic energies.

The wakefield behind the laser pulse is characterized.

The slingshot effect involves backward electron expulsion.

Abstract

We briefly report on some results regarding the impact of very short and intense laser pulses on a cold, low-density plasma initially at rest, and the consequent acceleration of plasma electrons to relativistic energies. Locally and for short times the pulse can be described by a transverse plane electromagnetic travelling-wave and the motion of the electrons by a purely Magneto-Fluido-Dynamical (MFD) model with a very simple dependence on the transverse electromagnetic potential, while the ions can be regarded as at rest; the Lorentz-Maxwell and continuity equations are reduced to the Hamilton equations of a Hamiltonian system with 1 degree of freedom, in the case of a plasma with constant initial density, or a collection of such systems otherwise. We can thus describe both the well-known "wakefield" behind the pulse and the recently predicted "slingshot effect", i.e. the backward expulsion of high energy electrons just after the laser pulse has hit the surface of the plasma.