Transverse field interaction multibeam amplifier

A transverse field interaction multi-beam amplifier device comprising a structure having, for example, a plurality of discrete cathodes cylindrically located in succession along a central axis of RF propagation is described. In registration with the cathodes are a respective number of annular collectors located within an outer cylinder which also acts as the structure housing. Intermediate to the cathodes and collectors are two additional coaxial cylinders, one having a relatively smaller diameter than the other, with the smaller diameter cylinder including respective number of discrete grids, while the large cylinder comprises a structure preferably having a rippled or undulating slow wave wall surface and a respective number of annular slots formed therein.