This invention relates to traveling wave tubes and more particularly to the method of manufacture of the slow-wave structure of a traveling wave tube which couples the incoming microwave energy at several tens of gigahertz frequency to the electron beam of the traveling wave tube in order to thereby amplify the incoming microwave energy and to provide the amplified microwave energy at the other end of the slow-wave structure.
This invention more specifically relates to multi-axis wire electric discharge machining methods for fabricating slow-wave structures, and in particular, a coupled cavity slow-wave structure for traveling wave tubes.
The conventional manner of constructing the coupled cavity slow-wave structure or delay line for the traveling wave tube is to fabricate the assembly from individually machined disks which can number in excess of one-hundred which must be brazed to a support structure to produce the delay line. Each disk has a portion of its periphery removed so that the cavities formed by the stack of laminations so that the cavity formed by an adjacent disks are coupled to adjacent cavities. The prior art technique of forming such an assembly results in a total parts cost which is very high together with problems in obtaining good control of dimensional tolerances - particularly, the pitch (the separation of the adjacent disks) which can have cumulative errors. The cost of making a delay line by the method of the prior art is substantial.