Electron injection and acceleration into laser-driven wakefield from a solid overdense plasma target

A laser–plasma acceleration scheme combining electron extraction from a solid overdense target with wakefield acceleration in an adjacent underdense plasma region is presented. A laser pulse excites a diffracted electromagnetic wave at the overdense plasma interface, extracting and pre-accelerating electrons, which are then injected into laser-driven wakefield cavities in the underdense plasma. A parametric study identifies key conditions enabling efficient electron injection and energy gain in this two-stage acceleration configuration. Two-dimensional particle-in-cell simulations performed with the Smilei code show that the proposed scheme produces electron bunches with a tunable trade-off between charge, energy, and beam quality at laser intensity I0λ02≃3.4×1019 W μm2/cm2 (λ0=0.8 μm). According to the parameters used, the electron beam is accelerated to peak energies of ∼150−250 MeV with an estimated charge in 3D of ∼50−400 pC integrated over the full width at half maximum energy range, and ∼100−1900 pC with energies above 50 MeV.