Design of a THz-driven compact relativistic electron source

A THz-pulse-driven compact, < 150 mm in total length, two-stage electron accelerator setup was designed. It uses 2 × 2 pairs of nearly counter-propagating focused THz pulses. The effects of the initial bunch charge and the propagation direction of the THz pulses on the energy of the accelerated electrons were investigated by numerical simulations. Generation of 8 fC electron bunches with up to 340 keV energy; only 2.0% energy spread and compressed on-target duration of 200 fs is predicted using single-cycle low-frequency THz pulses with less than 4.5 mJ total energy.