Electron Acceleration by Relativistic Surface Plasmons in Laser-Grating Interaction

Abstract

The generation of energetic electron bunches by the interaction of a short, ultraintense (I>10(19) W/cm(2)) laser pulse with "grating" targets has been investigated in a regime of ultrahigh pulse-to-prepulse contrast (10(12)). For incidence angles close to the resonant condition for surface plasmon excitation, a strong electron emission was observed within a narrow cone along the target surface, with energy spectra peaking at 5-8 MeV and total charge of ∼100 pC. Both the energy and the number of emitted electrons were strongly enhanced with respect to simple flat targets. The experimental data are closely reproduced by three-dimensional particle-in-cell simulations, which provide evidence for the generation of relativistic surface plasmons and for their role in driving the acceleration process. Besides the possible applications of the scheme as a compact, ultrashort source of MeV electrons, these results are a step forward in the development of high-field plasmonics.

Table-top laser-based proton acceleration in nanostructured targets

“…As there are several laser absorption mechanisms in overdense plasmas, such as the generation of surface plasma waves (SPW) [13,15,16,29,[31][32][33][34][35], resonant absorption, vacuum heating or J×B heating [36][37][38], one can use nanostructures with properties especially suited to enhance a particular absorption mechanism. Our aim is to optimize the acceleration of electrons in the vacuum gaps of a periodic structure, so-called vacuum heating [17,21,27].…”

Amplification of Relativistic Electron Bunches by Acceleration in Laser Fields

“…Such a situation is given when electrons are scattered out of a focal region due to the ponderomotive potential [21]. In order to obtain more energy from the laser field, additional concepts are exploited [2,3,9,11,18,19]. For example, the deceleration can be avoided when either the light field is reflected out of the electron trajectory [6,12,15,22] or when the electron is injected into the light field with a specific initial momentum [2,3,23,24].…”

“…The efficiency of the relativistic backscattering process is dependent on a high density and narrow spectral distribution of the electron layer. These requirements reason recent interests in investigating laser accelerated electron bunches from solid bulk targets [2,3,18] and from ultra-thin foil targets [9,19,20].…”

Targets for high repetition rate laser facilities: needs, challenges and perspectives

“…electron bunches in the interaction of relativistic laser pulses with solid surfaces has been recently observed and attributed to vacuum acceleration of electrons emitted by a plasma mirror [58] and to the excitation of high field plasmons from a modulated surface [59] .…”