Deep modulation of a high-current relativistic electron beam in a system of coupled cavities

The excitation of inphase (0-type) and antiphase (π-type) electromagnetic oscillations by a relativistic electron beam in a system of identical coupled cavities is considered. It is shown that, in the case of excitation of antiphase oscillations, instability develops in a shorter system of cavities than it does when inphase oscillations are excited. In the nonlinear stage of the excitation of antiphase oscillations in a system of coupled cavities, a virtual cathode forms that breaks the initially uniform relativistic electron beam into a periodic sequence of spatially separated short bunches.