Mode-interaction effects in spatial-harmonic magnetrons

Our results have shown that the usually used single-mode approximation of the magnetron cavity field works reasonably well only for modeling steady-state oscillations, and that this approximation does not allow to. study the build-up and non-stationary processes in spatial-harmonic magnetrons. In order to take the above processes into account, an approach which does not involve the mode expansions is used. The approach is based on a consideration of the "hot" magnetron oscillatory system as a closed distributed system made of nonlinear oscillators with lumped elements. The electromagnetic field acting on the electrons is calculated as a superposition of fields which are produced by the anode segments. The spatial structure of the cavity field, as well as the field-with-time evolution, is determined self-consistently by taking into account electron-wave, electron-electron, and electron-surface interactions. For the sake of convenience, the excited field structures are analyzed in terms of conventional cavity modes which are superposed.