The higher wave-guide mode of waves in helix slow wave structures of broadband TWTs

Numerical calculations of the fundamental mode oscillations and H₁₁ mode oscillations for helix slow wave structures (SWS), applied in broadband TWTs were made. Calculations were performed for three versions of a construction with various type and quantity of vane on an envelope. Cutoff frequency H₁₁ mode, electrodynamics characteristic and frequencies of π-type of the fundamental mode are calculated. Dependences of these frequencies on some geometrical sizes of elements of a SWS are gained.