Transverse modulation of an electron beam generated in self-modulated laser wakefield accelerator experiments

Low energy electron beams (E similar to 300 keV) generated in a self-modula ted laser wakefield accelerator experiment were observed to filament and be deflected away from the laser axis forming radial jets in the electron bea m profile. At higher energies (E > 900 keV), the filamentation and jets wer e suppressed and smooth electron beams copropagting with the laser were obs erved. The observed electron beam filamentation likely results from laser b eam filamentation in the plasma due to relativistic self-focusing effects. The radial jets of low energy electrons are likely caused by transverse eje ction of the electrons due to the radial structure of the wakefield and spa ce charge deflection of electrons as they exit the laser focus.