| Gyrotron traveling wave tube(TWT)based on cyclotron maser mechanism is a kind of vacuum gyrotron device,which can generate high-power,high-frequency and wideband millimeter wave and terahertz microwave power.It is widely used in millimeter wave radar systems,electronic countermeasure systems,plasma heating and other fields,and has attracted the attention of scientific researchers from all over the world.With the support of the national major project "XXX gyrotron TWT technology",this thesis is intended to investigate MIG and interaction circuit to realize high efficiency,wide frequency band,pulse and continuous wave compatibility of the tube.Meanwhile,the research and development of Ku-band dual-state gyro-TWT,Ka-band fully dielectric loaded broadband gyro-TWT and W-band high efficiency gyro-TWT have been carried out.The main research aspects and innovations are as follows:1.Based on the theory of uniform dielectric loaded waveguide,the propagation and loss characteristics of dielectric loaded waveguide modes are studied in detail.Then the small signal theory and large signal theory of gyrotron traveling wave tube based on dielectric loaded waveguide theory are derived and rearranged.Through theoretical analysis,a series of calculation programs are completed.The program can analyze the field distribution,propagation,attenuation,and other characteristics of dielectric loaded waveguide mode effectively,which can effectively predict the operating gain and bandwidth,and give the starting vibration characteristics of high-frequency circuit.It can be also applied to the study of the properties of Gyrotron TWT.2.Propagation and attenuation characteristics of dielectric loaded waveguide are analyzed in detail.An innovative interaction scheme is proposed to extend the operation frequency band by full dielectric loading on the interaction circuit of the Gyro-TWT.In the scheme,the dispersion characteristic of the waveguide is changed by loading dielectric,and the lossless dielectric is loaded to keep the electron beam and electromagnetic wave resonant in a wide frequency band.The structure of uniformly loading the lossy dielectric in the angular direction is adopted to suppress the parasitic mode competition and ensure the stable operation of the high frequency circuit.In this paper,the nonlinear self-consistent theory based on field matching theory and particle in cell simulation are used to analyze and study the interaction circuit.The results show that the tube obtain 100 kW saturated peak output power,44 d B saturation gain,15% efficiency and 3 d B saturated bandwidth(20% relative bandwidth)at 29 GHz.3.A MIG with curved structure is proposed and simulated annealing algorithm(SAA)and genetic algorithm(GA)are adopted for effective calculation and optimization.The problems of electron backflow and oscillation with high velocity ratio gun are studied.A cyclotron electron beam with a velocity spread of 0.9182% and a velocity ratio of 1.6 is presented.The global and local oscillations of Gyro-TWT are studied.The mode competition is effectively suppressed by employing the interaction circuit loaded with non-uniform dielectric.On this basis,dielectric materials with different thickness are fabricated and cold test is carried out.Finally,the oscillation and amplification characteristics of the interaction circuit are analyzed and studied.The results show that the output power of 36.24 kW,the saturation gain of 54 d B and the saturated bandwidth of 3 d B at 5 GHz are achieved at 93 GHz,and the maximum efficiency is 45.3%.4.A dual-band electron gun with low velocity spread which can meet the requirements of pulse and continuous wave operation has been proposed.Based on the multi-objective genetic algorithm,the structure of the gun is subdivided,and the electrical parameters are designed and optimized automatically.At the same time,redundancy of the gun are analyzed in detail.In addition,the interaction circuit loaded with Be O with high thermal conductivity is introduced to solve the mode competition problems of interaction circuit.Meanwhile,the power capacity of the tube is improved.Thermal analysis of the interaction circuit is carried out.Finally,a self-consistent nonlinear program and CST-PIC are used to simulate the interaction circuit,and the working characteristics and long-term stability of the tube are predicted.5.The hot test platform of Gyro-TWT is introduced in detail in this part.Based on the hot test platform,the Ku band gyrotron TWT are tested.Meanwhile,the test results are compared with the simulation results.On the premise of ensuring the stable operation of the tube,a long-time test is carried out to verify its ability of long-term stable operation.At the same time,the stability problems of electron beam current in the experiment are studied at the same time and the solutions are also given at last.The test results show that the tube has the ability of 150 kW pulse wave and 30 kW continuous wave power in the 8h operation. |
PDF Full Text Request