Analysis of the slow-wave structures used in the millimeter range devices
In this paper the slow-wave structures and their models, which are used for development of the millimeter range devices, are considered. The travelling-wave tubes (TWTs) of the millimeter range use rectangular and axially-symmetric resonator slow-wave structures. Analysis of these slow-wave structures was performed using HFSS program for 3D-modeling . Dispersion characteristics were calculated by program outlined in the paper . These characteristics are used to build the model of the slow-wave structure’s cell. The peculiarities of the interaction between the electrons and the field in the TWT with resonator slow-wave structures are determined by the nature of the field distribution in such structure. The discrete approach is the most common for solving problems of this type . The difference form of the electrodynamic excitation theory applied to the description of the discrete interaction is justifying the use of a mathematical model.
For a description of the TWT with the discrete interaction, in which the phase of the field in the interaction gaps in the longitudinal remains constant, the use of the difference equation is electrodynamically reasonable.
The more precisely defined the coefficients of the finite difference equations, the more accurate the mathematical model of the discrete interaction becomes. These coefficients have a certain electrodynamic meaning and are defined via coefficients of the quadripole transmission matrix derived from the sextopole if there is no the exciting current. The accuracy of the restoration of the electrodynamic characteristics of the modeled resonator slow-wave structures is determined by the coefficients of the quadripole obtained. Therefore, the correct selection of these coefficients provides a correct description of the discrete processes of interaction in travelling-wave tubes as well as the electrodynamic processes in the slow-wave structures.