Superradiance Mechanism-based X-band Relativistic Backward Wave Tube Research

The relativistic backward wave oscillator(RBWO) based on superradiance mechanism generates nanosecond/sub-nanosecond microwave pulse using superradiance effect of short electron pulse, and the microwave pulse has merits such as extra high peak power, narrow pulse, fast rise time. The peak power conversion efficiency could realize more than 100%. So the study on superradiance RBWO has much actual value.The superradiance mechanism in RBWO was studied systematically by associated method of particle simulation and experiment in this dissertation. The main contributions and features in this dissertation are as the following:1. The high frequency characteristics of slow wave structure were analyzed, and as a base anX-band RBWO based on superradiance mechanism was designed. Its electrical properties were studied by particle simulation software. The simulation indicated that microwave pulses of ～1.5GW peak power, ～700ps pulse width,～800ps risetime and output mode TM₀₁ were generated with beam voltage ～430kV, beam current ～4.0kA and guide magnetic field 2.0T, and that the peak power conversion efficiency reached 87.5%. The microwave radiance had superradiance nature, which was proved by the physical images of beam-wave interaction and the relation between beam pulse width and peak power. Further more, the generation condition and rules of superradiance in RBWO was analyzed.2. The design of resistance conversion, diode, magnetic field system, mode conversion, radiance antenna based on the existing Tesla pulse source was accomplished by theory analysis and numerical simulation. The experiment system of narrow pulse microwave device was built up providing experiment platform for superradiance RBWO.3. The preliminary experiment of X-band RBWO based on superradiance mechanism wasperformed at home. Limited by magnetic field condition, the experiment results under low magnetic field showed that microwave pulses of～360MW, 1.10ns pulse width, ～800ps risetime, ～9.15GHz frequency were produced with ～380kV beam voltage, ～4.5kA beam current and ～0.73T magnetic field, and that the peak power conversion efficiency was ～21%. The electrical properties analysis of RBWO in low magnetic field indicated that the output microwave pulses still had superradiance nature.