ABSTRACT
The relativistic magnetron, like its classical analogue, refers to instruments of the so-called resonance type with short-term interaction of the active medium (electron beam) with the electromagnetic field. The oscillatory system of the magnetron is a distributed electrodynamic structure and is multimodal. Oscillations of various types (modes) differ in eigenfrequencies and are characterized by spatial distributions of high-frequency fields in the resonator system. This property, as already noted, is the main cause of instability in the operation of generators, expressed in transitions between types of competing oscillations, frequency jumps and power. Modal instability is particularly pronounced when perturbations of the electrical modes of the device occur: in the pulsed mode, when working on unmatched loads, etc. Another powerful factor in the instability of relativistic magnetrons is the non-stationarity of plasma in the near-cathode region. The expansion of the cathode perturbs the synchronism condition and causes a significant frequency drift during the pulse.
