Design Of S-band Coaxial Relativistic Extended Interaction Cavity Osciallator

In the development of High Power Microwave,high output power and high efficiency are always the most important targets at HPM domain.Transit-Time Oscillator,a typical structure in HPM sources,has been great graces by researchers for its advantages,such as simple structure,high output power and pure frequency spectrum.In the research of Transit-Time Oscillator,foil structure and cylindrical structure have been widely applied in the majority of TTO.Relatively,coaxial structure has not been studied amply.Coaxial structure can increase the space-charge limiting current efficiently,the performance of coaxial structure is propitious to increasing output power of device.Based on the developing trend of HPM sources,a S-band coaxial relativistic extended interaction cavity oscillator is presented in this paper,and some detailed research has been done as follows:1.Firstly,the space-charge limiting current of coaxial structure is calculated.Corresponding results indicate that coaxial structure contributes to increasing the efficiency of device.And then guiding magnetic field which ensure transmission of electron beam in coaxial structure is analyzed.Finally,based on small-signal theory,the interaction processing of electron beam and ?-mode field is analyzed about single cavity and double cavity structure,respectively.Then the velocity and kinetic energy of electron leaving the gap are deduced.2.The main designing parameters of S-band coaxial relativistic extended interaction cavity oscillator are analyzed through the theory of HPM sources.And combined with actual technics,the designing standard of the main parameters is introduced.3.The high frequency characteristics of S-band coaxial relativistic extended interaction cavity oscillator is analyzed.The features of 0-mode and ?-mode of modulating cavity,and 01TM-mode of output cavity are investigated respectively.Then the influences between designing parameters and high frequency characteristics are studied,aiming to provide a guide to the design of S-band coaxial relativistic extended interaction cavity oscillator.4.The interaction between electron beam and modulating cavity,and the process of power extraction are studied,respectively.Then the whole structure of S-band coaxial relativistic extended interaction cavity oscillator is analyzed by PIC simulation.With a 900 kV,9kA electron beam guided by a magnetic field of 1T,the output power of the device is 2GW,the microwave frequency is 2.408 GHz,and the conversion efficiency is 24.7%.According to the research,there is a satisfactory output performance of S-band coaxial relativistic extended interaction cavity oscillator,which indicate that coaxial structure is feasible in the application of HPM sources,meanwhile the research is useful for further study of coaxial HPM sources.