AMPLIFICATION OF SLOW ELECTROMAGNETIC WAVE BY LONGITUDINAL NONPHASED ELECTRON BEAM IN INHOMOGENEOUS MAGNETIC FIELD.

The interaction of an electron, moving in an inhomogeneous magnetic field, with a circularly polarized plane electromagnetic wave is investigated. An equation is derived which describes the temporal change in the angle between the momentum vector of the electron and the electric vector of the wave field. It is shown that the electromagnetic waves can be amplified with high efficiency for relatively small amplitudes of the wave field at the expense of the energy of the rectilinear flow of electrons in an inhomogeneous magnetic field, which is not phased in at the entrance. The efficiency is comapred with that in the case of homogeneous field.