Generation of attosecond γ-ray pulse train driven by a Laguerre Gaussian laser in conical frustum

Attosecond γ-ray sources are indispensable for probing ultrafast and high-energy phenomena. However, achieving further pulse compression remains challenging, particularly through target structural modifications. Here, we propose a novel scheme that integrates a conical frustum target with a Laguerre–Gaussian (LG) laser to generate attosecond γ-ray pulse trains via inverse Compton scattering. By adjusting the tilt angle of the target, the longitudinal compression of the laser-driven electron sheet and the electron density distribution are controlled. Three-dimensional QED-PIC simulations show that optimizing the tilt angle compresses the γ-ray pulse duration from 500 as to 200 as while simultaneously increasing the orbital angular momentum (OAM) of the γ-photons. These γ-photons reach energies up to 410 MeV with a yield of approximately 10¹⁰. Meanwhile, a comparative analysis of the original and inverted structures reveals their respective advantages in generating γ-ray pulses. This work opens new possibilities for applications in nuclear resonance fluorescence, attosecond pump-probe diagnostics, and precision spectroscopy.