N-beam nonlinear traveling-wave amplifier analysis

In large-diameter electron stream traveling-wave amplifiers there is a significant variation of the circuit electric field across the stream. Most analyses neglect the effects of these field variations. An approximate method has been used to study the effect of transverse field variations on the gain and effciency of large-signal traveling-wave amplifiers. The annular electron stream is subdivided into a number of annular rings each containing an equal fraction of the total current. It is assumed that the circuit field varies over the stream cross section and that each segment has a different coupling to the circuit. The space-charge field is assumed independent of radius. The effect on gain and efficiency is calculated for a stream diameter of B = 1 and it is found that a subdivision of the stream into two segments with different couplings to the circuit gives a lower saturation efficiency but that further subdivision does not appreciably charge the results.