Partially Grounded Depressed Beam Collector

A novel depressed beam collector concept is described that can be relevant for klystrons and other linear beam tubes. In addition to the usual collector element or elements biased negatively to recover unspent-beam energy, a grounded element is introduced to collect reflected primary and backsteaming secondary electrons that, on account of transverse deflection, can be prevented from returning toward the cathode. A theoretical and simulation analysis is presented leading to the estimations of efficiency for this configuration, with examples that apply to a recently demonstrated L-band multibeam klystron. Efficiencies are predicted to be significantly higher for tubes employing partially grounded depressed collectors (DCs) than for tubes employing the conventional DCs.