Collector Efficiency Enhancement in TWTs through Beam Refocussing Section

Travelling wave tubes are generally known for their broadband operation, high gain and high efficiency of $\sim 60$%. Typically, such high efficient TWTs are highly desirable for space applications in satellite transponder. The overall efficiency of the TWT is increased by increasing any of its constituent – electronic, circuit or collector. Collector efficiency enhancement is an easier and effective way of increasing the overall efficiency. Here, to increase the collector efficiency, optimization of the magnetic field profile in beam refocusing section (BRS) has been performed. The percentage magnetization of the three periodic permanent magnets (PPM) in the BRS section has been changed to maximize the collector efficiency. The corresponding collector potential optimizations have been performed using genetic algorithm and the results have been compared with the ones obtained by manual optimization.