Self-modulation oscillatory modes in a relativistic backward-wave oscillator

We present the results of numerical simulation of nonlinear dynamics in a relativistic backwardwave oscillator (BWO) over a broad range of parameters. A comprehensive study of the onset of self-modulation is carried out. It is found that the self-modulation boundary in the parameter plane has a complex shape. This is due to the competition between two different dynamical modes leading to the instability of single-frequency stationary oscillations. It is shown that the transition to chaos through period doubling bifurcations characteristic of a nonrelativistic BWO exists only for small values of the relativistic factor γ0, while the transition through intermittency dominates for large γ0. © 1999 Kluwer Academic/Plenum Publishers.