Dispersion analysis in broadband helix traveling-wave tube

This paper focus on an issue that vacuum electronics engineers face while designing wide band slow-wave structures for traveling wave tubes: The obtaining of reasonably flat gain curve over the bandwidth. It is usual to try a tradeoff between synchronism and interaction impedance profile in order to achieve a better gain response. We show here results from an in house one-dimensional large signal code, which indicates that when a large variation in the electrical length of the circuit takes place (e.g. very wide band circuits) dispersion control has little effect on the gain profile.