Experimental evaluation of a novel depressed collector for linear beam microwave tubes

To date, conventional depressed collectors have yielded only moderate improvements in the overall efficiency of microwave tubes. Their basic deficiency was a premature onset of reflected primary and secondary electrons, which backstreamed into the tube at modest levels of depression. The approach pursued here involves a sphere combined with a central cone and a short spike protruding from the cone as a flexible geometry to effectively perform three functions at the same time; (to velocity sort the electrons, to show the electrons to a minimum realizable velocity at collection, and to prevent the back-steaming of secondary and reflected primary electrons into the interaction region of the tube). The experimental setup permitted the measurement of primary and secondary electrons arriving or leaving each collector electrode.