Research On Frequency-multiplying Electronic Gyro-amplifier

As a vacuum electronic device characterized by high power,high efficiency,high gain and wide bandwidth,the electronic gyro-amplifier has a very broad application prospects in communication,radar,medical,electronic countermeasures,and other fields in the millimeter and terahertz bands（30 GHz-1000 GHz）,and have attracted the attention of many researchers.The gyro-amplifier based on the electron cyclotron maser mechanism can effectively circumvent the co-scaling effect between the high-frequency structure and the operating wavelength faced of the traditional vacuum electronic devices,and has already shown excellent performance in the millimeter-band related system applications,and it is also the most probable source device that can generate high-efficiency and high-power radiation in the terahertz band at present.However,as electronic gyro-amplifier further expand towards the terahertz band,they encounter difficulties in obtaining high-frequency driving sources,at the same time,to ensure sufficient power capacity,they also face challenges such as low efficiency of high-order harmonic operation and fierce mode competition in high-order mode operation.In order to solve the above difficulties encountered in the development of gyro-amplifiers towards higher frequencies,this dissertation explores and researches for the first time a novel frequency multiplying gyro-amplification mechanism that can be driven by a low-frequency signal source and operates on fundamental electron cyclotron harmonics and low order modes,and the possibility and feasibility of this novel frequency multiplying amplification mechanism are thoroughly studied and analyzed.Based on the basic principle of electronic cyclotron masers,this dissertation explores the operating mechanism of a new type of frequency multiplying gyro-amplifier.The nonlinear interaction equation system of the frequency multiplying gyro-amplifier was derived,and a numerical simulation program was written to analyze the interaction process of the frequency multiplying gyro-amplifier.Based on the linear theory of gyro-amplifier,the parasitic oscillation in frequency multiplying gyro-amplifier were studied.On the basis of theoretical analysis,the beam-wave interaction process and specific state changes of a frequency multiplying gyro-amplifier were simulated using PIC simulation software,and an optimized design of a Ka-F band（F band:90 GHz-140 GHz）TE₀₁ mode fundamental harmonic quadruple frequency gyro-amplifier was completed.The main work of this dissertation is as follows:Firstly,based on the basic principle of electron cyclotron maser,the dispersion characteristics of the high-frequency structure that realizes the fundamental electron cyclotron harmonic operation,as well as the frequency-multiplying characteristics of the electron beam cyclotron angular frequency that realizes the high-frequency-multiplying output of the operating signal in a new type of frequency-multiplying gyro-amplifier,have been investigated.,and the operating mechanism of the new frequency multiplying gyro-amplifier was analyzed.The relationship between three key parameters,namely the operating magnetic field,velocity ratio,and guiding center radius,was studied for the Ka-F band TE₀₁ mode quadruple frequency gyro-amplifier to be designed,and the initial parameters of the quadruple frequency gyro-amplifier were determined.At the same time,a new implementation method of the three-stage operating magnetic field required for the frequency multiplying gyro-amplifier is proposed.Then,a detailed derivation of the self-consistent nonlinear theoretical equation system of the frequency multiplying gyro-amplifier was carried out in the electronic motion center coordinate system,and corresponding numerical simulation programs were written,which can be used to calculate the beam-wave interaction process of the gyro-amplifier.On the basis of quantitative analysis of dielectric loaded waveguide losses,the interaction structure models of the amplification and modulation section of the quadruple-frequency gyro-amplifier are established.By using nonlinear theoretical programs and PIC simulation software,a comparative analysis of the beam wave interaction results of the amplification section and the modulation section was conducted,verifying the reliability of the nonlinear program.The interaction state of the amplification section and the modulation section of the quadruple frequency gyro-amplifier was analyzed,and appropriate working and structural parameters were selected to ensure that the modulation section can effectively modulate the electron beam and the amplification section can achieve frequency multiplying and power amplifying output of high-frequency field.Meantime,a detailed analysis was conducted on the mode competition issues in the frequency multiplying gyro-amplifier.Based on the linear theory of gyro-amplifier,the starting current of absolutely unstable oscillations in quadruple frequency gyro-amplifier was studied.For the problem of backward wave oscillation,the starting current and starting length of backward wave oscillation were analyzed,and compared with nonlinear calculation results to verify the accuracy of linear theory.The starting threshold values for each oscillation mode were determined.Meanwhile,the influence of various parameters in the amplification section on its linear gain and bandwidth was studied using the linear gain formula,and the linear gain situation in the modulation section was analyzed.Finally,based on extensive theoretical analysis,the high-frequency structure design of the quadruple frequency gyro-amplifier was completed,and the high-frequency characteristics of the interaction structure were studied using commercial simulation software.Based on the study of high-frequency characteristics,a PIC simulation model was established to simulate the interaction of a quadruple frequency gyro-amplifier.The influence of operating parameter changes on the beam-wave interaction was studied,and the specific states of the electron beam and high-frequency field during the interaction process were analyzed in detail.The optimized simulation results show that the designed Ka-F band TE₀₁ mode fundamental harmonic quadruple frequency electronic gyro-amplifier with the Ka band input signal as the driving source achieves a maximum output power of 28.9 k W,an interaction efficiency of 16.51%,and a gain of 22.8 d B in the F-band.In the case of a driving signal bandwidth of 2.2 GHz,the effective operating bandwidth of the frequency multiplying output signal reaches 4.8 GHz,with a relative bandwidth greater than 4.4%,and an absolute bandwidth of-3 d B greater than 4 GHz.Through the research in this dissertation,the mechanism of the new type of frequency multiplying gyro-amplifier has been verified,and the feasibility of the new type of frequency multiplying gyro-amplifier has been demonstrated,providing new ideas for the development of gyro-amplifiers towards higher frequency bands.