The effect of conductivity losses on propagation through the helical slowwave structure of a travelingwave tube
Abstract
A general theory has been developed to account for the material conductivity losses on the performance characteristics of a helical slowwave structure (SWS) travelingwave tube (TWT). The effects of helix/envelope conductivity have been studied on various propagation parameters, namely, the axial propagation constant, the interaction impedance, the attenuation constant, and the equivalent circuit resistance per unit length of the structure. While with the first two of these parameters, these effects are found to be only of the second order, they are quite significant for the remaining two. The functional dependance of the propagation parameters on the other structure parameters of importance, namely, the relative permittivity of the helix supports, the envelopetohelix separation, the helix pitch angle, and the thickness of the helix wire, has also been shown. The generalized theory developed here has been further tested by comparing the results with those obtained elsewhere for some special cases. The theoretical results obtained in both the sheath and the tape models have also been compared with experimental results available elsewhere. The agreement between theory and experiment is found to be much closer in the tape model developed here than in the sheath model developed elsewhere.
 Publication:

IEEE Transactions on Electron Devices
 Pub Date:
 April 1988
 DOI:
 10.1109/16.2494
 Bibcode:
 1988ITED...35..549J
 Keywords:

 Electrical Resistivity;
 Electromagnetic Wave Transmission;
 Traveling Wave Tubes;
 Capacitance;
 Dielectrics;
 Electrical Impedance;
 Equivalent Circuits;
 Frequency Response;
 Electronics and Electrical Engineering