| Traveling wave tube (TWT) is the most important type of microwave vacuum tube. It has been frequently used as millimeter wave radar, guidance, tactical and strategic communication, electronic countermeasure, remote sense, radiation measurement and so on. Its performance directly influences the level of the weapon equipments, and it has importantly realistic significance for the study on the new type of high power and short mm-wave traveling wave amplifiers. In this dissertation, we have made detailed theoretical and experimental study on several types of rectangular waveguide grating slow wave structures (SWS). Several important and valuable results which bring forth new ideas are achieved and listed as the following:1. The theory of the double rectangular waveguide grating SWS with side walls is first derived, and the effects of the physical dimensions on the dispersion characteristics and the coupling impedance are obtained; the skin-dissipation effect is studied, the result is that the ratio of groove-depth to grating-period decides the magnitude of the dissipation; furthermore, the linear theory of the double rectangular waveguide grating TWT is also built, and the small signal analysis of this TWT is made.2. In order to decrease the phase velocity and enlarge the band width of rectangular waveguide SWS at certain groove-depth, the ridge-loaded and step-loaded rectangular waveguide grating structures are investigated. The dispersion equation and the coupling impedance expressions of this structure are obtained by means of field-matching method, the properties of the wave propagating through the structure are investigated by numerical calculation.3. The introduction of the dielectric layer loaded on the top plate of the SWS is a new idea that we proposed for extending the bandwidth of the structure. Theoretically, we have analyzed the effect of the loaded dielectric layer on the properties of the structure. The linear moving-plasma model is used to study the influence of the parameters of the dielectric layer on small signal gain of this kind of TWT, and theoretical results indicate that the dielectric-loading can increase the interaction frequency range, however, which leads a low gain.4. An approach to the analysis of the arbitrary-groove rectangular waveguide grating SWS is presented. The unified dispersion equation is obtained by means of an approximate field theory analysis; and the expression of the coupling impedance is also derived. Based on the theory, the effect of the groove shapes on radio-frequency characteristics of the structures is investigated by numerical calculation. Meanwhile, the linear model of the beam-wave interaction which is used to analyze the effect of groove shapes on small signal gain is built.5. Three kinds of rectangular waveguide grating structures (trapezoid, rectangular, dovetail) are manufactured successfully, and the dispersion properties of them are investigated experimentally, the cold test results are in good agreement with the theoretical results. Meanwhile, the in & output structure models are designed and made experimentally, the simulating results and the experimental results match very well.6. For decreasing the phase velocity further, the inner slotted rectangular waveguide grating slow wave structure is proposed, and is simulated by CST. The effect of physical dimensions on dispersion and coupling impedance is analyzed.7. In order to realize the power-composition in the tube, the multiple-array grating structure, that is, the photonic crystal structure is studied. This is fit for multiple electron beams. Based on the plane wave expansion method, the mixed plane wave expansion method which is based the integral equation is used to analyzed this structure. Its dispersion and band-structure are solved by numerical calculation.8. Dielectric loaded rectangular waveguide structure is studied based on dielectric loaded cylindrical waveguide. First, the dispersion relation is given by equivalent circuit and field matching, and the electromagnetic energy excited by a bunched relativistic electron beam is obtained by calculating the R/Q value. Second, the influence of dipole mode on the stability of electron beam is analyzed. Finally, we design a high power microwave generation device, and its operating frequency is 7.8 GHz. Test results are in good agreement with the predictions.
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