Theory of intermodulation in a klystron

A general theory of intermodulation in klystron amplifiers is presented. The formulation leads directly to the first algorithm for the computation of intermodulation products of all orders, including harmonic generation, at each gap in a multicavity klystron. The theory assumes one-dimensional (1-D) motion only, but takes explicitly into account all dynamical and space charge effects in 1-D to all orders in the modulation strength, including the combined effects of ballistic bunching and space-charge force. The theory reproduces the standard klystron results in the limit of a single-frequency input signal. A central result of the analysis is the derivation of a general expression for the current modulation in a drift tube, in terms of the velocity modulation of arbitrary temporal variation that is imposed at an upstream location.