Super-radiation Mechanism For Relativistic Backward Wave Tube A Preliminary Study

RBWO(Relativistic Backward Wave Oscillator)based on the superradiance mechanism could generate nanosecond/sub-nanosecond microwave pulses by using short electron pulses. The output superradiance pulses have many characteristics,such as ultra-high peak power, ultra-short pulse-width and very fast rising time.The power conversion efficiency of the superradiance could achieve more than 100%,which means that the peak power of the microwave could exceed the driving power of the electron beam.Therefore,the researches on RBWO in the superradiance mechanism have quite important theoretical and applied values.The superradiance mechanism in RBWO was studied by various methods such as the theoretical analysis,numerical computation and PIC simulation in this dissertation.The main conclusions and features in this dissertation are as following:1.Theoretical studies of the superradiance mechanism in RBWOThe non-static,nonlinear equations were derived from the basic Maxwell's and Lorentz's equations,which could describe the transient beam-wave interaction in an RBWO self-consistently.The information of the beam-wave interaction in an RBWO was obtained by solving the equations in the linear region analytically;the basic rules and features of the superradiance were figured out.Conditions of achieving superradiance and approaches of improving its peak output power were also brought forward.2.Numerical computation and optimization of RBWO in the superradiance regimeThe nonlinear consistent equations which could describe beam-wave transient interaction in an RBWO were solved by numerical computation.The basic rules,characteristics and optimizing approaches for the superradiance output in an RBWO were studied and discussed.3.The numerical analysis of the high frequency characteristics of SWS in an RBWOA new numerical method was put forward which could compute TM_0ndispersion curves in arbitrary axial symmetric periodic SWS(Slow-Wave-Structure)with or without an electron beam by using Field-Matching Method.As examples,the dispersion curves of a sinusoidal ripple waveguide and a disk-loaded waveguide were computed by using the developed Matlab codes,the agreements between the numerical results and the available simulation,and analytical results are quite satisfactory,while ours are with more efficiency and universality.4.PIC simulation and optimization of an X-band Superradiance RBWOAn X-band Superradiance RBWO was designed by using PIC simulation.It is indicated that a microwave pulse with the peak power～1.1GW,the pulse width～800ps,and～9.4GHz frequency was generated with the beam voltage～400KV,the beam current～2.5KA and the guide magnetic field 2.7T,the peak power conversion efficiency reached～110%.