Sectioned Gyrotron Backward-Wave Oscillator with a Zigzag-Shaped Quasioptical System: Spatiotemporal Theory and Some of Its Results

We develop the spatiotemporal theory of a gyrotron backward-wave oscillator (gyro-BWO) which allows broad frequency tuning and is based on the use of a sectioned quasi-optical system with a zigzag path of the signal wave beam. The theory explains the characteristic features of the dependences of the frequency and power of the output signal on the magnitude of the operating magnetic field. We study the competition between various modes of the system during the excitation of the auto-oscillator, predict the possibility of achieving auto-modulation generation regimes (including the regime with a short powerful superradiant pulse formed), and consider the hysteresis effect of frequency characteristics (when the operating magnetic field is varied over an extended generated pulse). Additionally, an external feedback system is proposed as a way to increase the generation efficiency.