Frequency and phase synchronization of a gyromonotron using a modulated electron beam

Phase locking is a phenomenon which involves synchronizing the phase and frequency of an oscillator to an external drive signal. Phase locked oscillators are attractive because they combine the high efficiencies characteristic of oscillators with the frequency and phase coherence provided by amplifiers. The results, using the NRL 4.5 GHz gyroklystron configuration[1] indicate that the use of two pre-bunching cavities reduces the power required for phase locking the gyromonotron by more than 15 dB from the case of direct injection of rf. The gain of this configuration is now in the 30-40 dB range and is comparable to that of the three-cavity gyroklystron amplifier. Priming, the synchronization in initial phase of a pulsed oscillator to an external CW driver, was achieved in the three-cavity system at drive powers more than 60 dB lower than in the direct injection case This three-cavity result also is on the order of 50 dB below the priming power required for equivalent phase control in magnetrons[2]. An investigation made into the response of the gyromonotron to an external signal was also made. Regions of amplifier behavior as well as soft and hard excitation of oscillation were observed. It is shown that the region of hard oscillations may be accessed by application of an external signal.