Modulation of intense relativistic electron beams by an external microwave source.
A novel mechanism capable of efficiently modulating intense relativistic electron beams is reported. This mechanism uses unique properties of slow and fast charge-density waves on an intense beam of a finite transverse dimension. The mechanism was investigated with use of an external microwave energy to excite these waves on a beam. Large-amplitude coherent and monochromatic current oscillations were detected on the electron beam at the same frequency as the external source. With use of this mechanism it becomes possible to construct efficient microwave amplifiers suitable for large rf accelerators.