Particle-in-cell simulations of CC-TWT for radar transmitters

TWT is one of the fundamental components in a Radar Transmitter and compared to Helix TWT, Coupled Cavity TWT (CCTWT) gives the highest power over a moderate bandwidth. A complete simulation of the TWT is very useful in avoiding iterations and failures in TWT development cycle. In this paper, the CCTWT designed in the X-band frequency range, has been simulated using the Eigen mode solver and the particle-in-cell solver of the three-dimensional software package, CST Microwave Studio. The slow wave structure along with the couplers is designed initially with the equivalent circuit approach and later optimized using the Eigen mode solver of CST MWS. The initial estimate of the total number of cavities and the number of cavities per section was obtained using large signal analysis which was later optimized using Particle-in-cell Solver of CST MWS. The Simulation predicted an output power of around 1 kW and 27 cavities.