Research On A 0.26 THz Photonic Crystal Gyrotron Oscillator

In recent years,the excellent characteristics of terahertz wave have gradually attracted people's attention.Terahertz technology has been widely studied.Terahertz radiation source is one of the key points.How to obtain high power and high frequency terahertz wave is a major technical challenge.The gyrotron based on electron cyclotron maser mechanism is a terahertz radiation source with great potential for development.In order to improve the working frequency and reduce the magnetic field demand,the gyrotron is generally in the state of high-order harmonics.In addition,in order to increase power capacity,it usually operates in the high-order mode.However,when gyrotron works in this state,there are other competitive modes,which seriously affect the performance of gyrotron devices,and cause great obstacles to improve the output power of gyrotron devices.The photonic crystal structure provides a feasible solution to solve these problems effectively.Photonic crystal is a kind of structure with spatial periodicity.The special treatment of this structure makes it impossible for certain modes of electromagnetic waves in the forbidden band to propagate outward,while other modes of electromagnetic waves can radiate outward,which has good mode selectivity and can solve many problems caused by gyrotron working in high-order mode.Therefore,the study of photonic crystal gyrotron oscillator is of great significance.In this paper,the design and implementation of a 0.26 THz photonic crystal gyrotron oscillator are studied through theoretical and simulation analysis of the photonic crystal gyrotron.The main contents include:1.Based on Maxwell's equations,the band gap properties of dielectric and metal lattices are analyzed by using the lattice theory of solid physics.The band gap diagrams of TE and TM waves of different lattices in different dielectrics and duty ratios are obtained by using PWM method.The global band gap diagrams of TE waves of regular triangular lattices with dielectrics of oxygen-free copper are obtained by software simulation.2.Using the equivalent radius method,according to the global band gap diagram of TE wave with oxygen-free copper triangular cylinder,the modes appearing in the forbidden band of different structures are obtained.In this paper,TE₀₄ mode with large mode spacing and angular symmetry is selected as the working mode.The field distribution of the mode in photonic crystal resonator is obtained by software simulation,and the variation of cavity quality factor and other parameters in different dielectric materials is analyzed.According to electromagnetic wave theory,the starting current and magnetic field of gyrotron at 0.26 THz are determined,and the competition mode and starting current of common waveguide resonator operating in this mode are compared.3.Based on the theory of magnetron injection electron gun and the related parameters mentioned above,a double-anode magnetron injection electron gun with transverse-longitudinal velocity ratio of 1.33 and guiding center radius of 0.97 mm was designed and optimized by software.