High efficiency TWT amplifiers

S. Naqvi, G.S. Kerslick, J.A. Nation, Q. Wang
Proceedings of the 1997 Particle Accelerator Conference (Cat. No.97CH36167)  
We report on a research program to increase the efficiency of relativistic traveling wave amplifiers to > 50%. The two stage amplifier consists of a bunching periodic structure with phase velocity significantly higher than the beam velocity and a decelerating section with phase velocity significantly lower than the beam velocity. The position of the decelerating stage with respect to the bunching stage is chosen such that the narrowest bunches are sustained in the decelerating field for the
more » ... g field for the longest possible time before significant debunching occurs. Two schemes are under investigation. In the first scheme, a resistive sever is placed between the two stages to suppress temporal phenomena. In the second scheme, the bunching and deceleration stages merge into each other by a gradual change in the iris radius over a wavelength. An absorbing section in this case is placed before the start of the bunching stage. Coaxial extraction geometry [1] is used in both schemes. Efficiencies obtained from MAGIC simulations are comparable to those obtained in high efficiency klystrons [2] (50-60%) but carry the important advantage of broad-bandwidth, low sensitivity on dimensions, low surface fields, and simplicity of design.
doi:10.1109/pac.1997.753127 fatcat:c5jfiknvrzfshj4qyua4wdsd44