Effective simulation of the radial thickness of helix for broad band, practical TWT´s

A generalized analytical model has been developed to simulate the radial thickness of the helix employed in practical traveling wave tubes. With this proposed model, the exact physical dimensions of the helix radial thickness can be incorporated in the design equations. Relevant dispersion relations, characteristic and interaction impedances, and equivalent circuit parameters are derived by making use of both the field theory and equivalent analysis methods. Besides, in the field theory approach, a novel technique has been introduced to reduce the complexity in the derivation of the design formula. The results obtained using the present model are critically assessed, for four different practical slow-wave structures, over a wide range of experimental frequencies and found to be better than those obtained using earlier models