A simulated annealing algorithm for optimizing RF power efficiency in coupled-cavity traveling-wave tubes

Decreasing the radio frequency (RF) phase velocity in the output section of a traveling-wave tube (TWT) is a technique commonly used to increase RF power efficiency. In order to optimize the profile of the phase velocity, a simulated annealing algorithm has been developed and implemented into the NASA multidimensional large-signal coupled-cavity TWT computer model. This algorithm allows the determination of the lengths of the individual cavities at the end of the output section necessary to provide the optimized phase velocity profile. The resulting nonlinear computer-generated phase velocity profile provides a design with optimized RF efficiency. In this paper, the optimization algorithm is described and computational results are shown. These results indicate an increase in center-frequency RF efficiency from 7.1 to 13.5% for a V-band coupled-cavity TWT