Towards Sub-TeV electron beams driven by ultra-short, ultra-intense laser pulses

Energetic electron beam generation from a thin foil target by the ponderomotive force of an ultra-intense circularly polarized laser pulse is investigated. Two-dimensional particle-in-cell (PIC) simulations show that laser pulses with intensity of 10²²-10²³ Wcm^-2 generate about 1-10 GeV electron beams, in agreement with the prediction of one-dimensional theory. When the laser intensity is at 10²⁴-10²⁵ Wcm^-2, the beam energy obtained from PIC simulations is lower than the values predicted by the theory. The radiation damping effect is considered, which is found to become important for the laser intensity higher than 10²⁵ Wcm^-2. The effect of laser focus positions is also discussed.