Study Of Beam-wave Interaction With High Efficiency In Twts

As the most widely-used microwave vacuum electronic devices, traveling-wave tube amplifiers(TWTs) have many advantages like high power and efficiency, broad bandwidth and working modes, good flexibility and reliability, which make them particularly important in many areas such as radar, EW(Electronic Warfare) and space communications. Beam-wave interaction is the most important part in the whole working process of TWT, and its efficiency can directly decide the performance of TWT. Therefore, efficiency study of beam-wave interaction in TWTs is very significant.The main work of this thesis:1. The basic theory of beam-wave interaction in TWTs is studied. The dispersion equation of the sheath model with metal shell is worked out and verified. Meanwhile, basing on the Eulerian linear theory of beam-wave interaction, relative phase angle, the very important parameter for analyzing the efficiency of beam-wave interaction, is studied.2. T-shaped vane, Shell-shaped vane and solid vane with separated block rod have been investigated. The capability of these vanes to effect dispersion and coupling impedance is compared. Among all these three kinds of vanes, the vane with separate dielectric support blocks can be easiest to get negative dispersion and the highest coupling impedance within same dispersion distribution, which means it can get the highest efficiency when used in TWTs.3. A new type of dynamic velocity taper structure with pitch groove for Helix TWTs is studied. The variation of the relative phase angle of fundamental wave and harmonic wave is investigated as the main parameters of this new structure changes. The result shows that this new type structure can raise the efficiency of beam-wave interaction significantly. And a considerable method for designing this new type of dynamic velocity taper structure is given.