3-D PIC simulation of quasi-phase matched direct laser electron acceleration with introduction of a precursor electron bunch

Summary form only given. Three-dimensional particle-in-cell simulation was applied to study the problem of quasi-phase matched (QPM) direct laser acceleration (DLA) of electron bunches. Energetic electron bunches can be efficiently accelerated by well-guided radially polarized laser pulses in density-modulated plasma waveguides. However, the electrostatic field arising from the plasma waves excited by the laser ponderomotive force causes the defocusing of the injected electron bunch, which limits the effective acceleration distance and deteriorates the produced bunch quality. In this study, we introduce an additional precursor electron bunch, which is injected at a proper time prior to the main accelerated electron bunch and the drive laser pulse. The precursor bunch induces a focusing electrostatic field in the background plasma to considerably reduce the transverse expansion of the accelerated electron bunch. The preliminary results show that the brightness of the accelerated electron bunch can be enhanced three-fold in a 2mm accelerating distance, as compared to the acceleration without a precursor bunch. The study demonstrates that the introduction of the precursor bunch could help realize a practical DLA-based electron source.