Limiting efficiency values of powerful klystrons

The results of a theoretical study of electron beam bunching processes in high-power multicavity klystrons are presented. The studies were carried out using one-dimensional and two-dimensional numerical models for different values of the space charge parameter. The data on the effect of stratification effects on the efficiency of klystrons with a different number of cavities are presented. As a result of the optimization of the cavities parameters, the limiting efficiency values that are achievable at different values of the space charge parameter are determined. The obtained fundamental dependence of the limiting efficiency values on the space charge parameter is compared with the empirical estimates of other specialists, as well as with experimental data obtained for record klystrons in leading klystron centers in our country and abroad. It is shown that the space charge parameter is a universal characteristic that determines the dependence of the efficiency of multicavity klystrons on the properties of the electron flow used. The prospects of increasing the efficiency of multi-resonator klystrons are indicated.