Charge separation by standing waves of strongly focused few-cycle laser pulses for particle acceleration

Electron and ion acceleration in laser beam-driven gas and solid-state plasmas are well-known and thoroughly investigated. Here, we propose and numerically investigate an ion acceleration scheme using the Coulomb explosion of ion bunches created by separating electron and ion bunches from gas plasma by the standing wave of counter-propagating THz/laser pulse pair(s). The low density and the supposed few-cycle-long THz/laser pulses ensure that simpler mechanisms play a role in the separation and acceleration processes, resulting in more predictable outcomes than in single-laser-beam-driven solid-state plasmas. The charge separation is investigated using the EPOCH PIC code. After the charge separation, the ion dynamics are followed by the GPT code. Calculations predict the generation of relativistic electron and ion bunches with sub-MeV average energy and a distribution well-suited to the very efficient use of the accelerated ions in ultrashort-pulse neutron sources.