Analysis of the excitation conditions of higher-mode oscillations in an orotron on the basis of nonlinear multifrequency theory

Nonlinear equations for the two-frequency regime of an orotron are derived, assuming a single-wave model for the interaction between the electron beam and the electromagnetic field. A numerical solution of these equations is used to analyze the excitation of higher-mode oscillations in an orotron with spherical mirrors. It is shown that the proposed theory yields exhaustive information about the operation of an orotron in the regime of fundamental and higher-mode oscillations.