Destructive Instabilities in Hollow Intense Relativistic Electron Beams

BS>It is found that a 400-keV, 10-40-kA, 50-nsec duration hollow relativistic electron beam suffers from a severe instability when injected into neutral gas along a magnetic field. The dependence of beam distortion on beam thickness, magnetic field strength, beam current, and proximity of the surrounding conducting walls is experimentally studied. The experimental observations are consistent with the diocotron instability occurring during the first several nanoseconds of the beam pulse. (auth)