An approach to the analysis of a finite thickness helix slow-wave structure by helical coordinate system

The helical slow-wave structure which has higher frequency and bigger output power is required in the development of high-power traveling wave tube. In view of this point, a thick tape helix SWS is analyzed in this paper. The radial field expression and dispersion equation are derived with the helical coordinate system. The effect of the helix thickness on the dispersion characteristic has been analyzed by numerical calculation. And the theoretical results by our approach have also been compared with those by HooK´s method. It shows that the data of our approach is closer to CST simulation. In the paper, we have theoretically modeled a helical SWS by a sheath helix of finite thickness that is treated by utilizing helical coordinate system to account for the finite thickness of the helix wire. The dispersion characteristics and the interaction impendence of the method have been compared with these of Hook´s models.