A linearly polarized Laguerre-Gaussian(LP-LG)laser beam with a twist index l=-1 has field structure that fundamentally differs from the field structure of a conventional linearly polarized Gaussian beam.Close to the axis of the LP-LG beam,the longitudinal electric and magnetic fields dominate over the transverse components.This structure offers an attractive opportunity to accelerate electrons in vacuum.It is shown,using three-dimensional particle-in-cell simulations,that this scenario can be realized by reflecting an LP-LG laser off a plasma with a sharp density gradient.The simulations indicate that a 600 TW LP-LG laser beam effectively injects electrons into the beam during the reflection.The electrons that are injected close to the laser axis experience a prolonged longitudinal acceleration by the longitudinal laser electric field.The electrons form distinct monoenergetic bunches with a small divergence angle.The energy in the most energetic bunch is 0.29 GeV.The bunch charge is 6 pC and its duration is approximately 270 as.The divergence angle is just 0.57°(10 mrad).By using a linearly polarized rather than a circularly polarized Laguerre-Gaussian beam,our scheme makes it easier to demonstrate the electron acceleration experimentally at a high-power laser facility.

Yin Shi;David R.Blackman;Ping Zhu;Alexey Arefiev

Department of Plasma Physics and Fusion Engineering,University of Science and Technology of China,Hefei,China;Department of Mechanical and Aerospace Engineering,University of California San Diego,La Jolla,CA USA;Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai,China

高功率激光科学与工程（英文版）

[1]Yin Shi;David R.Blackman;Ping Zhu;Alexey Arefiev-.Electron pulse train accelerated by a linearly polarized Laguerre-Gaussian laser beam)[J].高功率激光科学与工程（英文版）,2022(06):94-106

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