Analysis of transit-time oscillator devices in the slowly-varying amplitude approximation

Summary form only given, as follows. A relatively simple and fast-running computer code for the analysis of a wide class of transit-time oscillator (TTO) devices is considered. The code calculates the trajectories of a prescribed number of electrons as they cross a microwave cavity (a cylindrical pillbox, for example) in the presence of a particular cavity eigenmode. The particle motion is calculated numerically using an accurate fourth-order Runge-Kutta algorithm: during this integration, the mode amplitude is held constant. Energy transfer from the electrons to the microwave mode is calculated in the slowly varying amplitude approximation. A substantial number of test cases have been run using this model. The TM₀₁₁ , transvertron has been investigated in particular. In the small-signal regime. observed growth rates agree well with values calculated from previously derived formulas and with those observed in PIC (particle-in-cell) code simulations. The model also predicts values for saturation amplitudes and (in the case of loaded cavities) radiated power in good agreement with PIC code results