Fig. 5: Optimal regime of electron acceleration at oblique incidence.
From: Electron acceleration from transparent targets irradiated by ultra-intense helical laser beams
a Electron density ne normalized to the critical density nc at t = 26.6 fs for a target with an initial maximum electron density \({n}_{\max }=0.5{n}_{{{{{{{{\rm{c}}}}}}}}}\). b Electron energy distribution at t = 386.6 fs for different divergence angles \({\theta }_{\perp }={\tan }^{-1}\left({p}_{x}/\sqrt{{p}_{y}^{2}+{p}_{z}^{2}}\right)\). Only those electrons that have ∣y∣≤5 μm and ∣z∣≤5 μm are shown in this plot. c Electron energy spectra for the normal and oblique cases at the end of each simulation (t = tend). The spectra are for the electrons that are closer than 1 μm to the axis of the laser beam. Here tend = 398.3 fs for the case of normal incidence and tend = 386.6 fs for the case of oblique incidence.
