Abstract
Generation of energetic electron-positron pairs using multi-petawatt (PW) lasers has recently attracted increasing interest. However, some previous laser-driven positron beams have severe limitations in terms of energy spread, beam duration, density, and collimation. Here we propose a scheme for the generation of dense ultra-short quasi-monoenergetic positron bunches by colliding a twisted laser pulse with a Gaussian laser pulse. In this scheme, abundant γ-photons are first generated via nonlinear Compton scattering and positrons are subsequently generated during the head-on collision of γ-photons with the Gaussian laser pulse. Due to the unique structure of the twisted laser pulse, the positrons are confined by the radial electric fields and experience phase-locked-acceleration by the longitudinal electric field. Three-dimensional simulations demonstrate the generation of dense sub-femtosecond quasi-monoenergetic GeV positron bunches with tens of picocoulomb (pC) charge and extremely high brilliance above 1014 s−1 mm−2 mrad−2 eV−1, making them promising for applications in laboratory physics and high energy physics.
Highlights
Generation of energetic electron-positron pairs using multi-petawatt (PW) lasers has recently attracted increasing interest
In order to achieve both high yields of positrons and follow-up manipulation on the positron beam properties, here we propose an all-optical scheme for the generation of dense ultra-short quasi-monoenergetic positron bunches by use of a twisted laser pulse
Several methods have been proposed to mitigate this problem on positron wakefield acceleration from simulations[46,47] and experiments[48], but they generally require the pre-injection of monoenergetic positron beams, and these positrons are generally produced via the BH process
Summary
Generation of energetic electron-positron pairs using multi-petawatt (PW) lasers has recently attracted increasing interest. Different from the pure linear BW process, a significant number of pairs can be generated via the nonlinear BW process, where the energetic γ-photon beams propagate through an electromagnetic field, e.g., a laser pulse This makes it possible to generate copious positrons in a configuration of laser-laser or laser-electron collisions. Laguerre–Gaussian (LG) laser pulse is focused onto a cylindrical NCD plasma with a parabolic transverse density gradient, which can accelerate electrons directly from the background plasma to form sub-femtosecond electron bunches with energy up to several GeV These energetic electrons quiver strongly in the LG laser fields and collide head-on with a high-intensity scattering Gaussian laser field in the second stage, emitting abundant γphotons via the nonlinear Compton scattering (NCS) process. Dense sub-femtosecond quasi-monoenergetic GeV positron bunches are generated, which can be further accelerated in vacuum
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