Amplification of the tranverse waves of an electron beam in space -periodic magnetic-field jumps

In recent years electron beams with transverse modul ation have been appl ied for the amplification of microwave power. In a special variety of these amplifiers the electron beam passes a spatially variable static electric or magnetic field [l], [2], [3], [4], [9]. Transverse waves which propagate on an electron beam can be assumed to be independent of the space charge for beam deflections that are small with respect to the wavelength. Thus the model concept of a filamentary beam suffices for a description of such waves. The electron beam is here thought of as composed of disks without longitudinal coupling that have a diameter which is small compared to the wavelength. The center-of-mass trajectories of these disks behave just like the trajectories of individual electrons and suffice for a presentation of the waves [l].