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<p>Laser wakefield acceleration (LWFA) of electrons was investigated using quasi-3D Fourier–Bessel Particle-In-Cell (FBPIC) simulations to optimise the interplay between laser beam structure and plasma target parameters. Gaussian (G) and Bessel–Gauss (BG) beams driven by a 40&#xa0;mJ, 10&#xa0;fs laser pulse were compared, representing few-cycle mJ-class (10–100&#xa0;mJ) laser systems, across a range of the normalised vector potentials <i>a</i><sub><i>0</i></sub> = 1.75–5.6. The results show that, for a fixed laser system with 40&#xa0;mJ pulse energy and 10&#xa0;fs duration, BG beams extend the effective acceleration length and improve electron energy gain by 20–27% relative to G drivers, despite variations in <sub><i>0</i></sub> arising from different focal geometries. The extended focal zone of BG beams mitigates diffraction losses, while ionisation injection from a 1% nitrogen admixture produces stable injection over a distance of ~ 100&#xa0;μm at <i>a</i><sub><i>0</i></sub>​=2.0. However, laser pulse evolution leads to an intensity drop by a factor of 2–2.5 over 300–500&#xa0;μm, ultimately limiting the maximum acceleration length. These findings confirm that BG beams offer a robust pathway to enhance LWFA performance at sub-100&#xa0;mJ laser energies, with direct implications for compact high-repetition-rate plasma accelerators.</p>

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Beam shape effect on enhanced laser wakefield acceleration of electrons driven by 10-fs mJ-class pulses

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年2月26日

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  • Mehdi Abedi-Varaki,
  • Vidmantas Tomkus,
  • Valdas Girdauskas,
  • Gediminas Račiukaitis

摘要

Laser wakefield acceleration (LWFA) of electrons was investigated using quasi-3D Fourier–Bessel Particle-In-Cell (FBPIC) simulations to optimise the interplay between laser beam structure and plasma target parameters. Gaussian (G) and Bessel–Gauss (BG) beams driven by a 40 mJ, 10 fs laser pulse were compared, representing few-cycle mJ-class (10–100 mJ) laser systems, across a range of the normalised vector potentials a0 = 1.75–5.6. The results show that, for a fixed laser system with 40 mJ pulse energy and 10 fs duration, BG beams extend the effective acceleration length and improve electron energy gain by 20–27% relative to G drivers, despite variations in 0 arising from different focal geometries. The extended focal zone of BG beams mitigates diffraction losses, while ionisation injection from a 1% nitrogen admixture produces stable injection over a distance of ~ 100 μm at a0​=2.0. However, laser pulse evolution leads to an intensity drop by a factor of 2–2.5 over 300–500 μm, ultimately limiting the maximum acceleration length. These findings confirm that BG beams offer a robust pathway to enhance LWFA performance at sub-100 mJ laser energies, with direct implications for compact high-repetition-rate plasma accelerators.