Influence of particle fluxes from target on characteristics of intense electron beams

When a solid target is irradiated by an intense electron beam, surface processes take place leading to appearance of electron and ion fluxes, which influence on the characteristics of the beam. Electron flux from a target appears as a result of back scattering of beam electrons. Ion flux arises due to ionization of absorbed atoms and plasma formation on the target surface. In this paper results from experimental and numerical investigations of the influence of target particle of fluxes on the characteristics of electron beams from diode configurations are presented. It is shown that reflected electrons decrease the beam current and change also the distribution of the energy deposited by the electron beam into a target. The ion flux changes the spatial and temporal distribution of the beam current density at the target. The initially uniform distribution becomes nonuniform with a sharp maximum at the beam center. The influence of the target particle fluxes have to be taken into account when an electron beam is applied for irradiation of solids.