Millimeter dual helix traveling-wave tube

Results of the dual beam electron gun design studies have been incorporated into a reliable production type gun structure. The fixturing produced close tolerances needed for the small gun sizes. The size to length ratio caused severe broaching problems. These problems were solved by fabricating the barrel sections by milling, brazing and final machining. Deformation of the barrel, resulting from the final sizing broach operation, was eliminated by special fixtures. The use of a stripline in conjunction with a two section quarter wave transformer has produced a good match over the band. Two experimental Ku-band traveling-wave tubes have been built and evaluated. The evaluations indicate the limitations of this design.