Cumulation of High-current Electron Beams: Theory and Experiment

A drastic cumulation of current density caused by electrostatic repulsion in relativistic vacuum diodes with ring-type cathodes is described theoretically and confirmed experimentally. The distinctive feature of the suggested cumulation mechanism over the conventional one, which relies on focusing a high-current beam by its own magnetic field, is a very low energy spread of electrons in the region of maximal current density that stems from a laminar flow profile of the charged-particle beam.