Discrete-state simulated annealing for traveling-wave tube slow-wave circuit optimization

Algorithms based on simulated annealing (SA) have proven useful in designing traveling-wave tube (TWT) slow-wave circuits for high RF power efficiency. The main disadvantage of SA is that there is not a rigorous theoretical foundation for determining the cooling schedule parameters. The choice of these parameters is highly problem dependent and the designer needs to experiment in order to determine values that will provide a good optimization in a reasonable amount of computational time. In order to eliminate this disadvantage, a variation of SA known as discrete-state simulated annealing (DSSA) (Cantelmi, 2000) was recently developed. DSSA provides the theoretical foundation for a generic cooling schedule which is problem independent. Results of similar quality to SA can be obtained with significantly fewer iterations and without the extra computational time required to tune the cooling parameters. An algorithm based on DSSA was developed and programmed into a Microsoft Excel spreadsheet GUI to the 2D nonlinear multisignal helix traveling-wave amplifier analysis program TWA3 (MacGregor, 1993). The algorithm optimizes the computed RF power efficiency of a TWT by determining the phase velocity profile of the slow-wave circuit.