A S-band Extended Interaction Klystron Loaded By Metamaterials

The high-power klystron is a class of vacuum electronic device,which can converts the energy of electrons into the energy of microwave based on the speed modulation principle.The klystron has gone through for 80 years since the first klystron was developed.With the establishment of a variety of klystron theory,with the constant progress of electrical vacuum materials and technology and the related technical method,with the rapid development of computer simulation software,the efficiency,power,bandwidth,gain,and life of the klystron are greatly proved.It was widely used in the meteorological,communications,radio and television broadcasting,navigation radar and the electronic confrontation and other fields.The Extended Interaction Klystron(EIK)has both the advantage of klystron and travelling-wave tubes.It is a kind of high power and high efficiency microwave device with certain bandwidth.Recently,a new metamaterial suitable for miniaturized high-power vacuum electronic devices has been proposed,the backward-wave oscillator loaded by the metamaterial have been proved miniaturization and efficiency.In this paper,we will use the metamaterial suitable for miniaturized high-power vacuum electronic devices to design the EIK.Appling the metamaterial to the slow-wave structure of the EIK has a great prospect and may contribute to the miniaturization of the klystron and improve the efficiency of klystrons to further.In this paper,we designed a S-band EIK loaded by the metamaterial,and studied its beam-wave interaction.Firstly,this paper introduces the development of the EIK,and then systematically introduces the working principle of the klystron,including speed modulation,density modulation and output cavity energy exchange process.Finally,the design process of the klystron is given:1.The Extended Interaction resonator with the metamaterial is designed and its parameters are optimized by electromagnetic simulation software CST based on the theory of double-gap coupling cavity klystron.The intrinsic quality factor of the resonant cavity is 1956.4,the resonant frequency is 2.09 GHz,the characteristic impedance is 115.1.2.The working point of the electron parameter is calculated and the focusing system is designed.We select the coaxial line as the coupling structure of the input and output cavity,and simulate the of the input coupling cavity.By optimizing theparameters of the coupling structure,we get the highest gap voltage and the strongest interaction between electron and electric field.3.The optimal clustering distance of the EIK is calculated,and the particle simulation is carried out in the CST.We optimize the output resonant cavity coupling structure.finally,the length of the tube is about 14.93 cm,the working voltage is 11.3kV,Current is 1.2 A,when the input signal power is 32 W,the peak output voltage is 56 V,the output signal amplitude is 7 times of the input signal;the peak output power is2.178 kW,the gain is 18.38 dB,the electron injection DC power is 13.56 kW,the electron efficiency is 11.6%.Finally we find the trend of output power,gain and efficiency in various working parameters by simulation.