Abstract: An integral conductively-loaded encasing barrel for a slow-wave structure is formed by electrical discharge machining a plurality of circumferentially spaced longitudinally extending slots in the interior surface of the barrel. The machining discharge is established between a portion of the interior surface of the barrel and an electrode wire which is moved in a longitudinal direction within the barrel while the barrel is moved in a preselected manner in a plane transverse to the direction of movement of the wire. A subassembly comprising a slow-wave structure and a plurality of longitudinally disposed electrically insulating support rods in contact with and circumferentially spaced about the outer surface of the slow-wave structure is secured within the barrel with the support rods disposed within respective machined slots. The radially inwardly projecting portions of the barrel between the slots provide integral conductive loading for the slow-wave structure.

Abstract: A coupled cavity traveling-wave tube is disclosed wherein each interaction cavity has an oblong configuration in a plane perpendicular to the tube axis. The oblong cavities have a length-to-width ratio of a predetermined value between about 1.2 and 1.6, preferably being about 1.5. Coupling apertures in the end walls separating adjacent interaction cavities extend circumferentially about half way around aligned circular electron beam holes along the tube axis, with the circumferential extremeties of the coupling apertures lying substantially parallel to the length of the oblong interaction cavities.