Study Of Theory And Technique For Coupled Cavity Traveling Wave Tubes With Absorbed Buttons

Coupled cavity traveling wave tubes(CC-TWTs) are one of the most common high-power output traveling wave tube, which are widely used in high power applications such as warning radar, fire control radar and search radar etc. However because of its structure characteristics, CC-TWTs are easy to produce self-oscillations, which have serious impact on the performance of the TWTs.CC-TWTs may lead to many kinds of self-oscillations in the process of work, Such as forward wave self-oscillations, backward wave self-oscillations and band-edge oscillations, etc. among these self-oscillations, band-edge oscillations are most difficult to eliminate. At present the most commonly useful way to eliminate band-edge oscillations is putting two cylindrical absorbed cavities on both sides of the coupling slot in CCTWT. This type of CCTWTs can effectively suppress the band-edge oscillations and improve the output power of CCTWTs.This article mainly focused on the study of the theory and technique for CCTWTS with absorbed buttons, the main work includes the following aspects:1. Firstly the dispersion, total coupling impedance and attenuation of the coupled cavity high frequency structure are analyzed. And then make a deep analysis of the influence law of cavity structure parameters(such as the coupling slot opening angle, the coupling slot width, etc.). These research provides the basis for the following study.2. Theoretical analysis the reason and generation condition of spurious oscillations. Then briefly introduce the structure characteristics and working principle of CCTWTS with absorbed buttons. And analyzed the field patterns of the high frequency structure, explain the reason why this structure can suppress band-edge oscillations. Finally make a deep analysis of the influence law of absorbed buttons structure parameters(such as the depth of buttons, the angle of buttons, etc.). And on the basis, the process to design this type tubes is introduced. These research also provides the theory basis for the following research.3. Based on the characteristics of high frequency structure of CCTWTs, the most commonly used Curnow equivalent model are introduced. And the formula of dispersion and characteristic impedance for equivalent model are deduced in detail base on the Curnow model. The method of using ADS simulation software to the solving of dispersion has been proposed and the correctness of this method has been verified. The law of circuit capacitance and inductance influence on the equivalent circuit model has been summarized using this method. On this base, the equivalent circuit model of CCTWTs with absorbed buttons is analyzed. These research provides the theory basis for the calculation of wave interaction.