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

Abstract 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 incorporates a conical-frustum plasma target with a Laguerre–Gaussian laser to generate attosecond γ -ray pulse trains via nonlinear inverse Compton scattering. By tuning the target tilt angle, we control the longitudinal compression of the laser-driven electron sheet and the resulting electron-density distribution. Three-dimensional quantum-electrodynamic-particle-in-cell simulations indicate that, at the optimal tilt angle, the γ -ray pulse duration decreases from 500 as to 200 as, while the orbital angular momentum of the γ -photons is simultaneously enhanced. The emitted γ -photons reach energies up to 410 MeV with a total yield of approximately 10 10 . A comparative analysis of the original and inverted conical-frustum geometries further elucidates their respective advantages in γ -ray pulse generation. The present work opens new avenues for applications in nuclear-resonance fluorescence, attosecond pump–probe diagnostics and high-resolution imaging.