Abstract:
The helix of a high power traveling wave tube, i.e., in excess of ten watts cw, is supported from a thermally conductive barrelshaped metallic envelope via the intermediary of a plurality of beryllia or boron nitride rods disposed at circumferentially spaced locations around the periphery of the helix. The helix is anisotropically loaded for decreasing the positive dispersion or, in the alternative, producing a negative dispersion characteristic by means of a loading structure disposed surrounding the helix intermediate the helix and the barrel structure. In one embodiment, the loading structure comprises a plurality of arcuate quartz sectors having an array of longitudinally directed electrically conductive elements supported on the inside surface thereof adjacent the helix. In a second embodiment, the loading structure comprises a plurality of arcuate alumina sectors interposed between the helix and the surrounding barrel structure. These loading elements of both types greatly increase the operating bandwidth over which relatively high gain and efficiency are obtainable.