A Magnetron-Resonator System

Abstract

The present exposition deals with the fundamental multiplet spectrum of a multi-sectorial cavity or vane-type magnetron and specific applications involving the evaluation of the π-mode wave-length thereof. The consequence of mutual coupling between the sectorial cavities through the interaction space of an infinitely long anode is evaluated for the linear case and subsequently applied to the cylindrical case. Although both the qualitative and quantitative results are reasonable in the limit for relatively very long anodes, in practice the latter are relatively short and since the mode separation, order thereof, and hence the component wave-lengths are more or less influenced by the actual relative anode and end cavity lengths at each end of the anode, the results naturally differ from ``cold'' test data. Predictions of π-mode wave-length have been obtained to about 10 percent, depending upon the degree to which the parameters of the actual vane magnetron approximate the assumptions on which the present treatment is based. With the aid of ``cold'' test data the preliminary theoretically derived resonator geometry may be appropriately ``trimmed'' to produce the exact π-mode wave-length desired. Included in this article is a discussion of the need and function of straps of the resonator system and dimensional scaling, which preserve certain desirable properties of the prototype at the new wave-length, or operating point, in terms of magnetron performance-chart parameters. Finally, in Part III, a brief consideration is allotted to the derivation of the rectangular cavity or slot-type resonator system from the more general relation for the sectorial cavity in this article.