Dual beam multi-circuit traveling-wave tube

Abstract

The feasibility of multiple-coupled slow wave structures interacting with multiple electron beams in a single traveling-wave tube has been established. A device has been designed and constructed which delivers high output power levels over a broad instantaneous frequency range. A composite dual circuit structure consisting of countra-wound helices has been shown to support traveling-wave interaction with two electron beams. Suitably low dispersion characteristics have been combined with nominal interaction impedance to provide power across the 4 to 8 GHz octave bandwidth. Dual electron beams are provided by two distinct cathode structures, each of which has a separate and individually modulatable anode. Data has been recorded for both single and dual beam operation at various values of perveance. Novel backward wave oscillation suppression techniques, which are unique to the dual helix circuit geometry, have been included in the tube design. The dual electron beams are consistent with low operating voltages, which, in turn, make the tube compatible with common power supplies. For a given output power level, the overall size and weight will generally be smaller than that of tubes requiring higher operating voltages. The dual helix circuit has roughly twice the potential thermal capacity of a single helix structure. The design is tailored to dual mode operation with the high power mode supported by both electron beams and a low power mode supported by a single electron beam.