Tubular electron relativistic beam transport through nonregular cylindrical and coaxial waveguides in a strong longitudinal magnetic field

The phenomenon of beam current modulation at the frequency ∼ 1.3x109 Hz is experimentally found when the beam is passing the region of virtual cathode appearing during REB transport in a cylindrical waveguide with the expansion close to the collector. This phenomenon is shown to be explained by radial oscillations of current density excited in the beam. During REB transport in a coaxial and cylindrical regular waveguide beam azimuthal separation into streams takes place and beam current profile becomes nonstationary. This phenomenon reveals in current density oscillations and brings about an integral expansion of beam cross section and beam full current HF modulation, electron escape onto the waveguide wall and reduction of transported beam current