Direct acceleration of collimated high-energy attosecond electron bunches driven by intense Hermite-Gaussian lasers

Attosecond electron bunches hold significant promise for applications such as generating ultra-bright X/γ-ray and probing ultra-fast physical phenomena. However, the generation of high-quality attosecond electron bunches remains a challenge. Here, we propose a scheme for generating high-energy, collimated, attosecond electron bunches by employing an intense Hermite-Gaussian (HG) laser pulse. Three-dimensional (3D) particle-in-cell (PIC) simulations reveal that when a thin plasma target is irradiated by an HG₁₀ mode laser, electrons are extracted and subsequently undergo periodic modulation by the laser's optical field, leading to the formation of electron bunches with an attosecond duration of ∼200 as. Furthermore, the electrons experience continuous transverse compression due to the inward electric field force, which reduces the bunch divergence angle to approximately 0.7^∘. Simultaneously, the electron bunches are accelerated by the longitudinal electric field of the HG₁₀ mode laser pulse, gaining energy up to ∼2 GeV. Crucially, we also propose and validate via PIC simulations a feasible method for generating the required intense HG₁₀ mode lasers.