Linear and Saturated Behaviors of Gyrotron Oscillator With a Misaligned Electron Beam

The misalignment issue is not only an engineering challenge but also a problem of academic interest for the development of high-frequency gyrotron oscillators. In this article, the linear and saturated behavior of beam-wave interaction in gyrotron oscillator with an arbitrarily misaligned electron beam is studied in a general form. Misalignment causes eccentricity between the electron beam center and the resonator, resulting in the coupling strength loss and additional phase variation, which in turn affects the beam-wave interaction. The coupling strength loss leads to an increase in the starting current and the saturated current and a decrease in the saturated efficiency, while the additional phase variation modulates the cyclotron resonance condition and the electron bunching process, regulating the linear and nonlinear behavior of the gyrotron. The general analysis reveals that the diverse behaviors of misaligned gyrotron highly depend on the azimuthal mode index and the frequency cyclotron mismatch. The findings of this study offer valuable insights into the effects of misalignment on gyrotron operation and provide useful guidance for the design and alignment process of gyrotrons.