Dynamical behaviors of injection-locked gyrotron backward-wave oscillators

Summary form only given. The injection locking technique has been successfully applied to the gyrotron backward-wave oscillator (gyro-BWO) for phase control and spectral purity. Previous theoretical studies showed that the injected power is absorbed by the electron beam when the oscillator is locked. The relative phases between the electrons and the wave are adjusted by the absorbed energy, thus increase the time the bunched electrons staying in the phase of losing energy and enhance the efficiency of the gyro-BWO. However, the locking processes for the gyro-BWO are still unclear. The dynamical behavior of the injection-locked gyro-BWO is studied by a time-dependent particle simulation code. The injected power is temporally profiled for examining the dynamical response of gyro-BWO. The efficiency of gyro-BWO is enhanced with the increase of the injected power, and the oscillation turns to be free-running as the injected power is turned off. The time for locking or unlocking an oscillator is much shorter than the shortest rise/fall time of the temporal profile available in experiments. The effect of the injected power on the stability of gyro-BWO will also be studied and presented in the paper