In the article a double-gap cavity with anti-phase excitation that has wide application in designs of floating-drift klystrons is considered. One of the ways of reduction of time during machine design of klystron’s cavity is using of the simple analytical expression, allowing to determine the main klystron electrodynamic parameters with a sufficient accuracy for practice. In the article we presented the results of physical and mathematical modeling of the double-gap cavity, the corrected mathematical models were introduced that can be utilized in programs of a prompt optimization of klystron's type devices. The technique of creation of approximate mathematical model in this case was reduced to definition of basic analytical function, and the subsequent approximation between experimental and calculated data by means of a method of planned experiment. In presented work the analysis of adequacy was carry out. Analysis revealed inaccuracy of a resonance frequency of an anti-phase type in chosen ranges of change of influencing factors doesn’t exceed 1%, characteristic impedance- 5%. The received analytical ratios allow carrying out quickly calculation of parameters of the cavity, without labor-consuming and expensive experiments and calculations.
Keywords: double-gap cavity, electrodynamic parameters, mathematical simulation, resonance frequency, characteristic impedance, method of planned experiment
For miniaturized vacuum klystron type devices utilization of a double- gap strip-line cavity with suspended ceramic substrate is very promising.
The two-mode operating mode of such cavities practically isn't studied enough; so there is the great scientific and practical interest for research of electrodynamic characteristics of cavities during multi-mode operation that correspond to simultaneous excitement of anti-phase and co-phase modes in a double gap.
In this article results of the 3-D numerical modeling by means of the Ansoft HFSS code are presented, and also the experimental results of the electrodynamic properties of the half-wave double- gap cavity with the suspended ceramic substrate are submitted. Optimum parameters of this design, allowing to carry out simultaneous excitement at multiple frequencies with frequency rate (K=2) are determined.
In such cavity high values of unloaded Q factors isn’t need because dielectric losses and conductor losses can be compensated at the expense of the negative electronic conductivity that brought by modulated electronic beam. The operating mode with frequency rate can be used for increasing of efficiency of generating and amplifying micro devices with filament cathode and matrix field emission cathodes.
Keywords: double-gap cavity, electrodynamic parameters, mathematical simulation, resonance frequency, characteristic impedance, method of planned experiment