An Analysis of Klystron Reflector Performance

In this paper the performance of klystron reflectors is studied in detail. The electrostatic potential distribution in the reflector space is calculated by means of relaxation methods for three typical reflector designs. The transit time for electrons moving along the tube axis is calculated as a function of the h.f. voltage picked up in the resonator gap. With the help of the transit-time curves the bunching is studied in detail. The advantage of this analysis as compared with the treatment by other authors is twofold: the analysis is not confined to small signals, and it is possible to attribute tube defects to features of reflector design. It is shown that the power output and the transit times as deduced from the theory are in good agreement with experimental determinations. Off-axis electron paths are then computed by means of a step-by-step method. A consideration of these paths shows that space-charge effects are not likely to play an essential part in the performance of the tubes studied. In conclusion, the effect of the spatial focusing by the reflector on the tube impedance is discussed.