Modeling Oscillations in TWTs by Using the Tesla-Family of 2D Large-Signal Codes

Abstract

As a rule, codes that operate in the time domain, such as Particle in Cell (PIC) codes, are a more natural choice as a tool to explore the stability of beam-driven devices. However, the extensive computer resources required for PIC simulation as compared with those needed for hybrid codes such as TESLA1, motivate the development presented here. We report recent advances in the development of the TESLAfamily of 2D large-signal codes (such as TESLA-FW2 or TESLA-Z3, for example), with a focus on algorithms to model self-oscillations in TWT amplifiers. The TESLA codes operate essentially in the frequency domain, making it a challenge to find unstable modes without prior knowledge of their frequency.