Fig. 1. (a) Schematic layout of the microbunching scheme and its potential application. (b), (c) Electric field (E_y) of LG and Gaussian laser. The corresponding vector plot of the electric fields for (d1)–(d4) LG01 (σ = −1) and (e1)–(e4) Gaussian laser.

Fig. 2. (a), (b) Electron density maps generated by the LG laser at 20T and 100T. (e), (f) Electron density maps generated by the Gaussian laser under the same initial conditions as the LG laser. (c), (g) Longitudinal phase space distributions of electrons in (b) and (f). (d), (h) Comparison of the energy spectrum distribution and electron divergence generated by the LG and Gaussian lasers.

Fig. 3. (a) Current distribution modulated by the LG laser. Here, λ₀ = 0.8 µm. (b) Transverse electron distribution characteristics at 100T. (c) Trajectories of electrons in the multi-particle model. The black and red solid lines represent the electron trajectory in decelerating phase and accelerating phase, respectively. (d) Phase space distribution of electrons and longitudinal electric field (red line) distribution on the x axis at 5T (the hollow black circle represents the tested electrons with a uniform phase gap of 0.25π). Here, areas outlined in red and blue represent accelerating phase and decelerating phase, respectively.

Fig. 4. Comparison of the degree of bunching effects produced using a conventional undulator (CHG)^[22], PEHG scheme^[13], and the method proposed in this study. The red solid line represents the fitting line of the bunching effect. The x axis represents the modulation time of the electron beam and laser field.