High-energy coherent terahertz radiation emitted by wide-angle electron beams from a laser-wakefield accelerator

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High-charge electron beams produced by laser-wakefield accelerators are potentially novel, scalable sources of high-power terahertz radiation suitable for applications requiring high-intensity fields. When an intense laser pulse propagates in underdense plasma, it can generate femtosecond duration, self-injected picocoulomb electron bunches that accelerate on-axis to energies from 10s of MeV to several GeV, depending on laser intensity and plasma density. The process leading to the formation of the accelerating structure also generates non-injected, sub-picosecond duration, 1-2~MeV nanocoulomb electron beams emitted obliquely into a hollow cone around the laser propagation axis. These wide-angle beams are stable and depend weakly on laser and plasma parameters. Here we perform simulations to characterise the coherent transition radiation emitted by these beams if passed through a thin metal foil, or directly at the plasma-vacuum interface, showing that coherent terahertz radiation with 10s~$\mu$J to mJ-level energy can be produced with an optical to terahertz conversion efficiency up to 10^{-4}-10^{-3}.
Original languageEnglish
Article number043046
Number of pages21
JournalNew Journal of Physics
Early online date16 Mar 2018
Publication statusPublished - 20 Apr 2018


  • terahertz generation
  • laser-driven electron acceleration
  • electron beams

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