X-band Disk Loaded Backward Wave Oscillator Properties Study

The relativistic backward wave oscillator (RBWO) is one of the highest output power microwave sources today. As the main component of the beam-wave interaction of the backward wave oscillator for producing microwave energy, the slow-wave structure (SWS) is the key of the RBWO. It basically determines the performance of the RBWO. In the dissertation, the inner coaxial disk-loaded cylindrical waveguide used as SWS of Relativistic Backward-wave oscillator is discussed. Several valuable achievements are listed as the followings:1. The RBWO with inner coaxial disk loaded SWS is studied in the paper. The dispersion relation of the SWS is deduced according to Maxwell's equation and Floquet theory. Numerical analysis is carried out and the dispersion curves are gotten.2. The expression of the coupling impedance is obtained according to the field matching method. The effects of the structure on coupling impedance are discussed with numerical calculations.3. The linear theory of the coaxial disk-loaded cylindrical waveguide BWO is built and the dispersion equation with an annular electron beam of the BWO is obtained according to the field matching method. The computation results of the dispersion equation indicate the relations between the operating frequency and the small signal gain.4. The beam-wave interaction of the device is simulated and optimized by PIC method. Some important parameters of effecting the output power and efficiency are discussed in detail.The results of the study show that the RBWO with an inner coaxial disk-loaded structure has unique advantages: inner coaxial structure allows a larger radius electron beam to pass through the SWS, this will heavily decreases the space charge effects compared to a smaller radius beam with the same current. Hence the BWOs can work well with a lower axial guide magnetic field. The inner coaxial structure conductor is very easy to manufacture. It is a kind of promising high power microwave device.