MAGIC 2D simulation of nonstationary and chaotic processes in a relativistic backward wave oscillator

Abstract

Summary form only given. Study on non-stationary and transient processes is of major importance for the development of relativistic backward wave oscillators (BWOs). Such phenomena have been addressed by several works (starting from), both theoretically and experimentally. However, in the majority of works nonlinear dynamics of BWO is studied by means of simple 1 D nonstationary code based on slowly varying envelope approximation supposing reflections to be frequency independent. In an actual device, however, the reflections may depend strongly on frequency. This work is dedicated to the numerical modeling of transition to chaos in the relativistic BWO by MAGIC2D code and comparison with the results of numerical and experimental works. For the simulation, we selected the parameters of the BWO, described in, where chaotic generation of a MW power in a weakly relativistic BWO was achieved experimentally for the first time. The basic pattern of the dynamics revealed earlier in by simple 1 D nonstationary simulation remains valid. However MAGIC code takes into account several important physical phenomena, such as transverse electron motion, frequency dependence of the end reflections, and interaction with the forward non-synchronous wave. As a result, the pattern of dynamics differs in some extent from that described in, more precisely, there is a combination of the scenarios typical for resonant and non-resonant BWO. Our results are also in a good agreement with the experimental works and emphasize the importance of reflections in the dynamics of a relativistic BWO.