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 dada of our approach is closer to CST simulation. The traveling wave tube (TWT) is the most important device used for amplification of energy at microwave frequencies. It is widely used in communications, radar transmitters and electronic countermeasures. The slow-wave structure, where the electron beam interacts with the guided electromagnetic slow wave, plays the most important role in TWT It basically determines the microwave performance of the TWT. TWTS most commonly use helix slow-wave structure[1-3]. In the past analysis method, the thickness of the helix wire usually is ignored. In fact, the parameter greatly affects accuracy of the ending result. Some scholars[3] studied the affection of the thickness of the helix wire by unitizing the Hook model in which the helix wire is equivalent to helical thin conductive surface. While, the calculation results of these methods have some discrepancy with the experimental ones.