In this study, we investigate the self-generated the electric and magnetic fields effects of fast electrons beam on plasma and beam characteristics. The fields effect as; columbic transverse electric field, radial space charge potential, longitudinal plasma wakefield and transverse self magnetic field on beam propagational characteristics as; a collimated or focused and filamented beam and the plasma density perturbation are investigated. Also the hollowing effect due to self magnetic field which can generate an annular pattern in electrons beam is investigated.
