| 摘要 |
A structure to eliminate non-fundamental space harmonics in helical traveling wave tubes (10) is disclosed. The helix (18) radius (24a, 24b) and pitch (22a, 22b) are simultaneously varied over a short distance to improve the efficiency and performance of the tube (10). This new geometry, an adverse space harmonics taper (ASHT), renders the fundamental phase velocity invariant to frequency and distance effects, while adversely affecting all other space harmonics. Another aspect of the invention reduces the temperature of the helix (18) and further improves tube efficiency, so that electronic efficiencies approach 30% in a linear performance region.
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