Coherent terahertz radiation emitted by wide-angle electron beams from a laser-wakefield accelerator

Brunetti, Enrico and Yang, Xue and Jaroszynski, Dino A.; Jaroszynski, Dino A. and Hur, MinSup, eds. (2019) Coherent terahertz radiation emitted by wide-angle electron beams from a laser-wakefield accelerator. In: Proceedings Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources III. Proceedings of SPIE, 11036 . SPIE, CZE. ISBN 9781510627383 (https://doi.org/10.1117/12.2523178)

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Abstract

Laser-wakefield accelerators generate femtosecond-duration electron bunches with energies from 10s of MeV to several GeV in millimetre distances by exploiting the large accelerating gradients created when a high-intensity laser pulse propagates in an underdense plasma. The process governing the formation of the accelerating structure ("bubble'') also causes the generation of sub-picosecond duration, 1-2~MeV nanocoulomb electron beams emitted obliquely into a hollow cone around the laser propagation axis. We present simulations showing that these wide-angle beams can be used to produce coherent transition radiation in the 0.1-5 THz frequency range with 10s~$\mu$J to mJ-level energy if passed through an inserted metal foil, or directly at the plasma-vacuum interface. We investigate how the properties of terahertz radiation change with foil size, position and orientation. The bunch length and size of wide-angle beams increase quickly as the electrons leave the accelerator, causing a shift of the radiation frequency peak from about 1 THz at a distance of 0.1~mm from the accelerator exit to 0.2 THz at 1~mm. If the foil size is reduced, for example to match the typical diameter of the plasma channel formed in a laser-wakefield accelerator, simulating the emission from the plasma-vacuum boundary, the low-frequency side of the spectrum is suppressed. The charge of wide-angle electron beams is expected to increase linearly with the laser intensity, with a corresponding quadratic increase of the terahertz radiation energy, potentially paving the way for mJ-level sources of coherent terahertz radiation.

  • Item type:Book Section
    ID code:69363
    Dates:
    Date
    Event
    24 April 2019
    Published
    4 March 2019
    Accepted
    Notes:Copyright 2019 Society of Photo‑Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this publication for a fee or for commercial purposes, and modification of the contents of the publication are prohibited.
    Subjects:Science > Physics
    Department:Faculty of Science > Physics
    Technology and Innovation Centre > Advanced Science and Technology
    Depositing user: Pure Administrator
    Date deposited:14 Aug 2019 11:49
    Last modified:08 Apr 2024 13:55
    URI:https://strathprints.strath.ac.uk/id/eprint/69363
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