Simulation of conditions for the maximal efficiency of decimeter-wave klystrons

Using the mathematical model of electron beam transformation in a narrow tube developed by the authors and the KlypWin program suite, conditions for the maximal efficiency of decimeter-wave klystrons having from three to six amplification stages are simulated. Simulation is based on a real electron-optical system and real parameters of the cavities. It is shown that the maximal efficiency (across the load) is 83% for a four-cavity klystron, 86% for a five-cavity klystron, 88% for a six-cavity klystron, and 90% for a seven-cavity one. The electronic efficiency of the simulated seven-cavity klystron equals 94%, which implies the achievement of a global extremum.