Quasimonoenergetic Electron Beams with Relativistic Energies and Ultrashort Duration from Laser-Solid Interactions at 0.5 kHz

Mordovanakis, Aghapi; Easter, James; Naumova, Natalia; Popov, Konstantin; Masson-Laborde, P. E.; Hou, Bixue; Соколов, И. В.; Mourou, G.; Glazyrin, I. V.; Rozmus, W.; Bychenkov, V. Yu.; Nees, J.; Krushelnick, K.

doi:10.1103/physrevlett.103.235001

Cited by 75 publications

(63 citation statements)

References 23 publications

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“…1b). Although there have been some observations of electron ejection from solid surfaces [30][31][32][33], the experimental parameters did not permit to reach the VLA regime we have identified in this work, the intensity being too low (< 10 19 W/cm 2 ) or the gradient scale length too long.…”

Section: Plasma Mirrors As Electron Injectorsmentioning

confidence: 86%

Vacuum laser acceleration of relativistic electrons using plasma mirror injectors

et al. 2015

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Accelerating particles to relativistic energies over very short distances using lasers has been a long standing goal in physics. Among the various schemes proposed for electrons, vacuum laser acceleration has attracted considerable interest and has been extensively studied theoretically because of its appealing simplicity: electrons interact with an intense laser field in vacuum and can be continuously accelerated, provided they remain at a given phase of the field until they escape the laser beam. But demonstrating this effect experimentally has proved extremely challenging, as it imposes stringent requirements on the conditions of injection of electrons in the laser field. Here, we solve this long-standing experimental problem for the first time by using a plasma mirror to inject electrons in an ultraintense laser field, and obtain clear evidence of vacuum laser acceleration.With the advent of PetaWatt class lasers, this scheme could provide a competitive source of very high charge (nC) and ultrashort relativistic electron beams.1 arXiv:1511.05936v1 [physics.plasm-ph] 18 Nov 2015Femtosecond lasers currently achieve light intensities at focus that far exceed 10 18 W/cm 2 at near infrared wavelengths [1]. One of the great prospects of these extreme intensities is the laser-driven acceleration of electrons to relativistic energies within very short distances.At present, the most advanced scheme consists of using ultraintense laser pulses to excite large amplitude wakefields in underdense plasmas, providing extremely high accelerating gradients in the order of 100 GV/m [2]. However, over the past decades, the direct acceleration of electrons by light in vacuum has also attracted considerable interest and has been extensively studied theoretically [3][4][5][6][7][8][9][10][11]. These investigations have been driven by the fundamental interest of this most elementary interaction, and by its potential for extreme electron acceleration through electric fields of > 10's TV/m that ultraintense laser pulses provide.The underlying idea is to inject free electrons into an ultraintense laser field so that they always remain within a given half optical cycle of the field, where they constantly gain energy until they leave the focal volume. 1D Analytical calculations [3] show that for relativistic electrons, the maximum energy gain from this process is ∆E ∝ mc 2 γ 0 a 2 0 , where γ 0 is the electron initial Lorentz factor, and a 0 is the normalized laser vector potential, m the electron mass, and c the vacuum light velocity. Reaching high energy gains thus requires high initial energies γ 0 1 and/or ultrahigh laser amplitudes (a 0 1).In contrast with the large body of theoretical work published on this vacuum laser acceleration (VLA) of electrons to relativistic energies, experimental observations have largely remained elusive [12][13][14][15][16][17] -sometimes even controversial [18,19]-and have so far not demonstrated significant energy gains. This is because VLA occurs efficiently only for electrons injected in t...

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Section: Plasma Mirrors As Electron Injectorsmentioning

confidence: 86%

Vacuum laser acceleration of relativistic electrons using plasma mirror injectors

et al. 2015

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“…20 The diversity in the results can be explained by the fact that these experiments used different gradient scale lengths and intensities. Experiments with a controlled gradient 18,21 as well as numerical simulations showed that the electron emission is more efficient when the gradient scale length is around L ' k 0 =10. Evidently, the gradient scale length is a crucial parameter as it determines the dominant laser absorption mechanism: J Â B heating 22 and vacuum heating [23][24][25] at short L, resonant absorption 26 at intermediate L, or parametric instabilities at longer L.…”

Section: Articles You May Be Interested Inmentioning

confidence: 99%

“…[13][14][15][16][17] to few MeV. 18 Some experiments reported on beams emitted in the specular direction, 18 while others reported on beams emitted along the surface 19 or in the normal direction. 20 The diversity in the results can be explained by the fact that these experiments used different gradient scale lengths and intensities.…”

Section: Articles You May Be Interested Inmentioning

confidence: 99%

On the physics of electron ejection from laser-irradiated overdense plasmas

2016

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International audienceUsing 1D and 2D PIC simulations, we describe and model the backward ejection of electron bunches when a laser pulse reflects off an overdense plasma with a short density gradient on its front side. The dependence on the laser intensity and gradient scale length is studied. It is found that during each laser period, the incident laser pulse generates a large charge-separation field, or plasma capacitor, which accelerates an attosecond bunch of electrons toward vacuum. This process is maximized for short gradient scale lengths and collapses when the gradient scale length is comparable to the laser wavelength. We develop a model that reproduces the electron dynamics and the dependence on laser intensity and gradient scale length. This process is shown to be strongly linked with high harmonic generation via the Relativistic Oscillating Mirror mechanism. VC 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)

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“…In some experiments, the energy spectrum of the electrons emitted from the plasma at a large angle of incidence of the laser beam on the solid target surface contained quasi-monoenergetic bunches of accelerated electrons, Refs. [19,20]. It was shown that a critically important factor in this case is the existence of preplasma, which is induced by the relatively low contrast of the laser pulse.…”

Section: Introductionmentioning

confidence: 99%

Collimated quasi-monochromatic beams of accelerated electrons in the interaction of a weak-contrast intense femtosecond laser pulse with a metal foil

Malkov

Stepanov

Yashunin

et al. 2013

High Pow Laser Sci Eng

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We demonstrated experimentally the formation of monoenergetic beams of accelerated electrons by focusing femtosecond laser radiation with an intensity of 2 × 10 17 W/cm 2 onto the edge of an aluminum foil. The electrons had energy distributions peaking in the 0.2-0.8 MeV range with energy spread less than 20%. The acceleration mechanism related to the generation of a plasma wave as a result of self-modulation instability of a laser pulse in a dense plasma formed by a prepulse (arriving 12 ns before the main pulse) is considered. One-dimensional and two-dimensional Particle in Cell (PIC) simulations of the laser-plasma interaction showed that effective excitation of a plasma wave as well as trapping and acceleration of an electron beam with an energy on the order of 1 MeV may occur in the presence of sharp gradients in plasma density and in the temporal shape of the pulse.

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Quasimonoenergetic Electron Beams with Relativistic Energies and Ultrashort Duration from Laser-Solid Interactions at 0.5 kHz

Cited by 75 publications

References 23 publications

Vacuum laser acceleration of relativistic electrons using plasma mirror injectors

Vacuum laser acceleration of relativistic electrons using plasma mirror injectors

On the physics of electron ejection from laser-irradiated overdense plasmas

Collimated quasi-monochromatic beams of accelerated electrons in the interaction of a weak-contrast intense femtosecond laser pulse with a metal foil

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