Research On Magnetron Injected Gun Of A Ultra-wideband Continuously Adjustable Terahertz Gyrotron

Terahertz technology as a frontier science and technology with broad application prospects,has received in-depth research in recent decades.At present,with the aim of exploring the application of terahertz technology,many types of new terahertz radiation sources have been developed.Among them,gyrotron is an important member of terahertz radiation source device family,has been favored by a large number of researchers because of its ability to generate broadband and high-power electromagnetic waves in the millimeter-wave and sub-millimeter-wave bands.And gyrotron is expected to be widely used in many fields including satellite communication,electronic countermeasures,and dynamic nuclear polarization nuclear magnetic resonance(DNP-NMR)spectroscopy.The magnetron injection electron gun(MIG)can generate an electron beam for the gyrotron.The quality of electron beam will have an important effect on the output power and beam-wave interaction efficiency of the gyrotron.Supported by the research projects in our group,this paper condoucts a lot of numerical calculations and analysis based on the in-depth study of electron optics theory.With the PIC software,the design of MIG for a 0.5THz continuous-wave frequency-tunable gyrotron was conducted.The MIG can produce electron beams with low velocity spread and high pitch factor to meet the requirements of the gyrotron.The main research contents are:1.Starting from the most basic Maxwell equations,systematically analyze and explain the theory of electron optics.Based on the theory of conservation of angular momentum and the theory of adiabatic compression,the basic theory of the MIG was elaborated in detail,and a set of equations used to calculate the initial structural parameters of the MIG was analyzed,derived and summarized.These equations provide a theoretical basis for the design and research of MIG.2.According to the basic theory of electron optics and the performance requirements of the gyrotron,the PIC software is used to design a single-anode MIG and a dual-anode MIG for 0.5THz continuous wave frequency adjustable gyrotron.The velocity spread and velocity pitch factor of the single-anode MIG are 2.7% and 1.3,respectively.The velocity spread and velocity pitch factor of the dual-anode MIG are6.7% and 1.4,respectively.Both types of magnetron injection electron guns meet theperformance requirements of the gyrotron for the electron beam.3.There are often some deviations between the simulation data of the MIG and the actual experiments.These deviations are often caused by machining accuracy,assembly errors,and errors in equipment.In view of this,in order to reduce the error between experiment and simulation,this paper considers these possible deviations in the design stage of the MIG.For example,in the design process,by adjusting the structural parameters and electrical parameters of the MIG within a certain range,the errors that may exist during the actual experiment are simulated.Thus,the fault tolerance of the MIG in subsequent thermal testing experiments is improved.Finally,after observing and analyzing the effects of electrical and structural parameters on the performance of the electron beam,a set of methods for optimizing the structure of the MIG to improve the performance of the electron beam was concluded.